/ ; o& ,ay THE SHEAR, EATIGUE, BEND, IMPACT, AND EGNG-TIME-LCAD STRENGTH PRCPERTIES OE STRUCTURAL METAE-TC-METAE ADHESIVE* IN BCNDS TC 24S-T3 ALUMINUM AEECY June 1953 ov- I - - This Report is One of a Series Issued in Cooperation with the AIR rORCE-NAVy-CIVIl SUBCOMMITTEE on MRCRAET DESIGN CRITERIA Under the Supervision off the AIRCRAFT COMMITTEE of the MUNITIONS BOARD No. 1836 UNITED STATES DEPARTMENT OF AGRICULTURE FOREST SERVICE FOREST PRODUCTS LABORATORY Madison 5, Wisconsin In Cooperation with the University of Wisconsin Table of Contents Page Summary . 1 Introduction 2 Test materials and procedures. ..................... 3 Types and preparation of specimens. ................ 4 Number and distribution of test specimens. „ 6 Methods of test. .................................. . 7 Results and discussion. 11 Conclusions. 18 Tables 1 Bonding conditions used in preparing lap- joint specimens 2 S 2a Summary of test results 3 - 20 Individual fatigue test data 21 - 30 Individual long-time-load test data Figures 1, 2 Photographs of shear test apparatus 3-6 Photographs of fatigue test apparatus 7-9 Photographs of long-time-load test apparatus 10 - 25 SN (stress -number of cycles to failure) curves for fatigue tests 26 - 33 Stress-time to failure curves for long-time -load tests Report No. 1836 -l- Digitized by the Internet Archive in 2013 http://archive.org/details/shearfaOOfore THE SHEAR, FATIGUE, BEND, IMPACT, AND LONG- TIME -LOAD STRENGTH PROPERTIES OF STRUCTUR A L METAL TO-METAL ADHES1VES IN BONDS TO 24S-T3 ALUMINUM ALLOyI' h 1 By H. W. EICKNER, Engineer Forest Products Laboratory, — Forest Service U. S. Department of Agriculture Summary The shear, fatigue, bend, impact, and long time -load strength properties of nine commercially available adhesives, of the type formulated for structurally bonding metal to metal, were determined by procedures des- cribed in Air Force Specification No, 14164, "Adhesive, Metal to Metal, Structural," September 20, 1949 These procedures consisted of testing lap joints of 0, 064-inch 24S-T3 clad aluminum alloy in shear at 72 a to 76° F. , at 178° to 182* F, , at -65 s to -70 s F , after exposure to salt- water spray, and after immersion in aircraft fluids; in fatigue at 7 2° to 76° F. and at -65® to -70° F, ; in long-time loading at 72 s to 76" F and at 178* to 182* F ; and in bending at 72 s to 76 s F Bonds between 24ST3 bare aluminum blocks were also tested in impact resistance at 72° to 76° F. and at -65" to -70° F. —This progress report is one of a series prepared and distributed by the Forest Products Laboratory under U. S Navy Bureau of Aeronautics Order No. NAer 13 19 and U. S. Air Force No, USAF- 18(600) = 70. Results here reported are preliminary and may be revised as additional data become available, —The fatigue tests for this study were made under the supervision of Wayne C, Lewis, Engineer, Forest Products Laboratory z.The test data included in this study on the shear strength of the adhesive bonds after exposure to salt-water spray and after immersion in aircraft fluids and on bend and impact strength were taken from Wright Air De- velopment Center Report RDO No. 614-11, "Properties of Adhesive Bonded Aluminum Alloy Lap Joints, " by B, W, Andrews, U- S, Air Force. ^Maintained at Madison, Wis. , in cooperation with the University of Wisconsin, Report No. 1836 -1- Agriculture-Madison The adhesives tested in this study by the static shear tests at 72* to 76° F . at 178° to 182" F. . and at 65° to 70* F. generally met the requirements of the Air Force Specification No. 14164 with the exception of two adhesives, one in the low - temperature tests and one in the high temperature test. The average values for the shear strength of both these adhesives were so close to the requirements, however that, for practical purposes, all adhesives tested can be considered to meet these shear strength requirements. The shear strength values obtained on the aluminum lap-joint speci- mens after exposure to salt water spray and after immersion in air- c raft fluids also generally met with a few exceptions, the requirements of the spe> ifi< at:on. Two of the nine adhesives tested for fatigue strength failed to meet the requirement of the Air Force Specification for fatigue strength at 72* to 76* F. The other adhesives had good fatigue properties and the failures in many of the tests, particularly at low stresses and at -65* to 70* F. , were tension failures in the metal rather than in the adhesive bond. Five of the nine adhesives tested did not meet the requirements of the Air Force Specification for strength in long time loading at 178* to 182" F All of the adhesives met the actual strength requirements of the long time loading test at 72* to 76* F. , but five showed a greater deformation in the adhesive bond during 200 hours of loading at 72* to 76* F, than is permitted by the Air Force Specification. All of the adhesives tested met the bend strength requirement of the specification. Only one of the adhesives tested however produced bonds with impact strength values at both 72* to 76* F and -65* to 70 F that exceeded the minimum requirements of the specification. Several rer ommer.da tions for possible changes in the Air Force Spec ifi< atiox) No. 14164 are made based on the experience obtained from the tests in this study. 'r.troduction Adhesives have been formulated during the past 10 years that give good bonding of metals to metals, wood and low density core materials ne preliminary evaluation of bonds made with these adhesives Report No. 1836 showed that the adhesives are suitable for making high strength struc- tural bonds, these adhesives are now being used for many structural and nonstructural applications in aircraft construction. In such con- struction, adhesive bonding has advantages over fastening with rivets In the speed of the operation, in more uniform distribution of stresses from one structural member to another, and in the production of smoother airfoil sections. These adhesives have also made possible metal faced sandwich constructions that have high stiffness for their weight. Air Force Specification No. 14164, "Adhesive, Metal to Metal, Struc- tural;" September 20, 1949, prescribes certain requirements for adhe- sives for structurally bonding metal to metal in aircraft. The main requirements of this specification include the shear strength in lap joints of clad aluminum alloy at 7 2® to 76® F. , at -65® to =70° F. , at 178® to 182® F. , after exposure to salt-water spray s and after immer- sion in aircraft fluids; the fatigue resistance of these bonded joints at 72® to 76® F. and at -65® to =70® F. ; and their longtime -load strength at 72® to 76® F. and at 178® to 182® F. ; and their bend strength at 72® to 76® F. Impact strength properties at 72® to 76® F. and at 65 s to YQ® p between adhesive -bonded aluminum blocks are also required. At the time this specification was issued the performance requirements were based on a limited amount of data obtained on a few adhesives or on earlier data obtained by test methods that differed slightly from those finally adopted for the specification. The purpose of this study was, first, to evaluate in the manner pre- scribed by the Air Force Specification a number of the principal metal- bonding adhesives that are currently being used in the aircraft industry and s second, to determine from the results of the tests the advisability of changing certain testing techniques or performance requirements of the specification. The bonding conditions used with the adhesives were within the range recommended by the adhesive manufacturer, and, therefore, the test data will indicate whether these typical adhesives meet the present requirements of Air Force Specification No, 14164, Test Materials and Procedures Adhesive Processes The adhesive processes evaluated in this study were? Adhesive 25 » a high-temperature -setting formulation of the neopreie phenolic type. Report No. 1836 -3~ Adhesive 25 ^primer) and Adhesive 26 (secondary) (this process will be subsequently referred to as adhesive 25-26) -- adhesive 25 used in (cmbu.atior. with secondary adhesive 26, which is a high -tempera- ture-setting formulation of the phenol resin type used as a secondary adhesive for primed metal surfaces This secondary adhesive is used when pressures must be lower than those that give good bonds with the direct bonding adhesive 25 alone. Adhesive 55 a high - temperature - setting adhesive formulation of the vinyl phenolic type This adhesive has been reported to have the same composition as adhesive 35, except that it is prepared by another adhesive manufacturer. Because of the reported similarity, only a limited number of tests were made to compare the performance of adhesive 55 with adhesive 35. Adhesive 34 a high temper atur e- setting, two - component formula- tion of a phenol resin solution and a vinyl polymer powder. Adhesive 35 a high ■ temperature setting formulation of the vinyl - phenclic type. Adhesive J6 a high temperature setting adhesive formulation of the neoprer.e phenolic type. Adhesive 37 • adhesive 36 used in ccmbmation with a second resin component containing a nylon resin m order to obtain better flow characteristics than those obtained with adhesive 36 alone. Adhesive 38 ■ an adhesive process similar to adhesive 37, except that the two resin components were impregnated on a nylon-fabric tape. Two bonding runs were made with adhesive tape manufactured by differ- ent manufacturers. Adhesive 41 a formulation of epoxv tvpe resins that was cured, for this study, at a temperature of 200* F. Type s an d Prepa ration of Specimens The lap joint specimens prepared and tested in this study were of two types 1/2- and 3/8 inch overlap of 0. 064 inch 24S T3 clad alumi- num alloy AN A 13) as specified m Air Force Specification No. 14164. Report No 1836 The lap-joint specimens were prepared for the shear tests at the three test temperatures long time load tests, and fatigue tests by bonding together two 4 by 13-inch pieces of 0. 064-inch, clad alu- minum alloy with a 1/2 or 3/8 -inch overlap. Ten lap joint speci- mens, 1 inch wide and approximately 7-1/2 inches long y were then cut from each of the bonded panels with a metal-cutting handsaw operating at such a speed that there was no appreciable heating or observed damaging of the specimens. Lap-joint specimens for the salt-water spray and fluid immersion tests were prepared in 6-inch-wide test panels of the l/2-inch lap joint from which five l~inch-wide specimens could be cut. Two specimens were cut from the outer edges of these panels as controls before exposing, and the other three test specimens were cut from each of the panels after exposure to salt-water spray or immersion in the aircraft fluids. The impact test specimens were prepared by bonding together 6 -inch- long strips of 3/8™ by 1-inch and 3/4- by l = 3/4-inch bare 24S-T3 aluminum alloy bars. The two bars were bonded together in step- wise fashion with the 1-inch face of the smaller bar bonded to the 1-3/4-inch face of the other bar and with the back edges of both bars in the same plane. Five 1-inch-wide test specimens were then cut with a metal cutting saw from each of these bonded assemblies. All bonding surfaces of the aluminum alloy were cleaned by first wiping the surfaces with a clean cloth saturated with benzene, and then immersing the metal for 10 minutes at 140® to 160® F in a solution of the following composition by weight; 1 part of sodium dichromate, 10 parts of concentrated sulfuric acid s and 30 parts of water. After removal from the solution, the surfaces were thoroughly rinsed in cold and in warm tap water and quickly dried. The clean metal surfaces were bonded with the several adhesives under the bonding conditions given in table 1. The bonding conditions were within the range recommended by the adhesive manufacturers for use with their adhesives at the time of this study. The adhesive was always applied to the metal surfaces within 2 hours after the surfaces were cleaned. The lap-joint specimens for the bend and immersion tests were made in a separate bonding run from that used in preparing the specimens for the shear, long-time-load ; and fatigue tests. The bonding condi- tions, however, were essentially those given in table 1. Report No, 1836 Num ber and Distribution of Test Specimens For tests 1, 2, 3, 6 and 7 ol the Air Force Specification 14164, nine panels ,90 specimens) of the l/2 inch-overlap type were prepared with each of the adhesive processes evaluated in this study. Specimens for the tests were selected in the following manner (test specimens were numbered 1 through 10 across each of the bonded panels): Test 1, shear strength at 72* to 76" F. -- Specimens 1, 5, and 10 from each panel (27 specimens). Test 2 shear strength at 178* to 182° F. -- Specimen 8 from each panel 9 specimens). Test 3, shear strength at 65* to -70* F. -- Specimen 7 from panels 1 through 6 v 6 specimens). Test 6, long-time strength at 72* to 76° F. -- Specimens 3, 4, and 9 of odd-numbered panels and specimens 4 and 9 of even-numbered panels Zi specimens). Test 1, long time strength at 178° to 182* F. -- Specimens 2, 3, and 6 of even numbered panels and specimens 2 and 6 of odd -numbered panels 22 specimens). 'Specimen 7 of panels 7, 8, and 9 - extra specimens used for creep tests when required ) For tests 4 and 5 of the Air Force Specification No 14164, six panels 60 specimens) of the 3/8-inch-overlap type were also prepared with each of the adhesive processes, and the specimens for testing were selected lr. the following manner: Test 4 fatigue strength at 72° to 76* F. -- Specimens 2 3 and 4 of even numbered panels and specimens 7, 8, and 9 of odd numbered panels v 18 specimens). Control B shear test at 72° to 76" F. - Specimens 1 and 5 of even- numbered panels and specimens 6 and 10 of odd numbered panels '12 spec lmer.s). Test 5 fatigue strength at -65* to 70° F - - Specimens 7, 8, and 9 of even numbered panels and specimens 2 3 and 4 of odd -numbered panels 18 spec lmens). Control statu shear test at -65* to -70* F. - - Specimens 6 and 10 of even numbered panels and specimens 1 and 5 of odd -numbered panels (12 spec lmens). Report No 1836 6 For tests 8 and 11 through 16 of the Air Force Specification No. 14164, 13 6 inch -wide test panels of l/2-inch lap-joints of 0. 064 -inch clad 24S TJ aluminum alloy bonded with each adhesive were divided in 6 groups of 2 panels each for exposure to the salt-water spray and immer sion conditions and a single panel for the bend tests. Specimens 1 -inch wide were cut from the outer edges of each panel for controls, and the center portion was exposed or tested. For tests 9 and 10 of the Air Force Specification No. 14164, 10 1 inch- wide specimens for testing in impact, 5 at 72° F. (test 9) and 5 at 65™ to 70® F. (test 10), were cut from the 2 6-inch»wide assemblies of aluminum bars bonded together with each of the adhesives. Methods of Test Unless otherwise noted, the adhesive processes were evaluated by the methods specified in tests 1 through 16 of Air Force Specification No. 14164. Tests 1, 2, and 3, Lap-shear strength at 72 @ to 76® F. , at 178® to 182° F. , and at - 65® to -70® F. - The individual test specimens were placed in Templin-type testing grips, with the jaws of the grips extend- ing over the specimen, so that the ends of the jaws were 1 inch from the overlap area. Loads were applied in tension on the grips with a uni- versal-type hydraulic testing machine loaded at such a rate that the stress was applied on the joint area at a rate of 600 pounds per square inch per minute (300 pounds per one-half square inch per minute). For the tests at 178 s to 182® F. and at =65® to -70® F. , suitable cham = bers at the test temperature were placed around the specimen in the test machine (figs. 1 and 2) to ensure that the adhesive bond was stressed at the specified temperature. The general practice in testing metal lap joint specimens at elevated temperatures at the Forest Products Laboratory has been to place the specimen in the test grip within the chamber at the desired temperature, closing the door of the chamber rapidly so that the heat loss would be at a minimum, and then to start loading of the test specimen 2 to 4 minutes after the test chamber reaches the desired temperature. As the test chambers used for this study were moderately efficient, approximately 10 minutes were allowed between the placing of the specimen in the test grip and the loading of the test specimen This method of testing was used for the first groups of specimens tested at Report No. 1836 -7- 178° to 182* F Air Force Spec if ic ation No 14164, however, states that the properties of the adhesive bonds shall be determined after exposure for at least one -half hour to the controlled temperature >. ondition Therefore all later specimens were tested after exposure for one half hour instead of 10 minutes The use of the JO • minute exposure would normally be expected to give approximately the same results as the 10 minute exposure at 178" to 182* F , except for adhesives that were not completely cured in the original cure cycle There is no reason to believe however, that any of the adhesives in this study received significant additional cure at 178* to 182° F. Aging of adhesive bonds at 178* to 182* F might decrease the shear strength at this temperature range but there was no indication that the additional 20 minutes at 178" to 182* F. before testing affected the test results obtained on the adhesives evaluated in the pr esent wo r k Tests 4 and 5 Fatigue strength- at 1 Z z to 76' F and at 65* to 70* F. As controls four specimens ^two specimens at each temper- ature condition* from each of the bonded panels having 3/8 inch lap joints were tested statically in shear at 72* to 76* F. and at 65* to 70* F. by the same test procedures as were used for tests 1 and 3 The control specimens selected for testing at each temperature were the two outside spec imens from groups of five adjacent specimens from one panel, with the three center specimens being tested in fatigue at the same temperature For the fatigue tests specimens with i/8 inch lap joints were cut to over all length of 5-7/8 inches and were placed m test grips of the type shown in figure i The grips were designed so th^t the plane of loading (produi ed by lines through the center of the pins in the grips' coincided with the plane of the glue line in the unloaded speci- men The distance from the end of the lap in the specimen to the grips was 1 inch The details of these grips are sho vl r, m figure 4 The lap joint specimens were loaded in tension through the grips by B direct stress fatigue machine of 4 000 pound capacity (fig 5.). This machine was equipped with electronic controls so that if the specimen failed or the maximum repeated load decreased more tl 15 pounds, the machine stopped automatical iv until the loading was rected Specimens were loaded at a rate cf 900 cycles per minute 5 Fatigue strength tests at 72° to 76° F were previously made on adhesive 35 in a cooperative project with the Air Force and therefore, only check tests of the fatigue data previously obtained were made in this study Report No. 1836 8 Individual test specimens were placed in the machine, and various loads placed on them in tension before the loading cycles were started, Loading in any cycle varied from the maximum selected to 10 percent of that maximum. The 10 percent minimum was selected, rather than the 1 percent required by Specification No. 14164, because it was believed that the precision at the 1 -percent level might actually result in placing the specimen in slight compression at indeterminate times. Actual maximum loads were selected to give a range in num- ber of cycles to failure regularly spaced from at least 10 million cycles to not more than 5, 000 cycles. Automatic counters recorded the cycles of loading to failure. Tests at room temperature were made in a controlled room where the relative humidity and temperature were maintained at 50 percent and 75® F. , respectively. For the fatigue tests made at -65® to 70® F. , it was necessary to enclose the test specimens in a cooling chamber of the type shown in figure 6= Dry ice was placed in trays in the center of the chamber s and a circulating fan equipped with a thermostat control was used to maintain the temperature on the surface of the specimen near the joint at =65® to 70® F. The test machine was also provided with controls that stopped the tests when the testing temperature became warmer than -50® F. Tests 6 and 7. Long-time -load st rength a t 72® to 76® F. and at 178® to 182® F. --Data on the strength in long-time loading of the bonded joints were obtained by applying dead loads to specimens with l/2-inch lap joints by the use of a cantilever loading apparatus i,fig° 7). The specimens were placed in a test fixture of the type shown In figure 8 and were held in place by 3/8 -inch-diameter pins passed through the test fixture and through 13/32 -inch holes in the ends of the specimens. The test fixture was attached to the frame of the test machine and, through metal straps, to the loading lever. Weights were added to the ends of the lever to apply the proper stress to the test specimens. Each of the levers of the test machine was calibrated with a standard steel bar attached to an electric strain gage so that the actual applied loads were known for the various weights applied at the end of the various levers. Loads selected to produce failures, with regular spacing over a range varying from at least 200 hours to less than 1 hour, were applied to each group of specimens. Before the test specimens were loaded; the loading lever was raised with a hydraulic jack and the specimen was placed in the test fixture. The proper weights, as determined from calibration data s were placed at the end of the lever, The hydraulic Report No, 1836 >ack was then released at such a rate that the desired load was applied in 2 to 3 minutes The clocks shown in the background of figure 7 were started, and the starting time was recorded These clocks were in circuit with a switch that stopped them when the specimen failed and the lever arm dropped. Weighted threads with a rosin coating were looped over the shaft of the minute hand of the clocks, so that displace- ment of this thread would indicate the day and hour of failure For the standard-temperature tests the temperature of the room in which the loading was done was maintained at 72* to 76° F. For the high temperature tests a chamber heated by electric light bulbs (fig. 8) was thermostatically controlled, so that the adhesive in the lap joint was at a temperature of 178* to 182* F. For those bonds that did not fail in 200 hours of loading at either tern perature, measurements were taker, of the amount of deformation of the adhesive bond at that time Before they were loaded, a fine line had been scribed on the specimens across the polished edge of the bonded joint normal to the plane of the aluminum sheet. To determine the deformation of the bond, the offset of this line was measured with a measuring microscope fig 9' both when the specimen was under load and or.e week after removal of the load from the specimen Test 8 Bend strength at 72" to 76" F. - Bend strength values were obtained on the 1/ 2 inch lap joint specimens by center u g the specimens flatwise for test as a simple beam, loaded at the center over a 1-1/2- mch span The supports and loading blocks were rounded to a radius of 1/4 inch at the point of contact Load was applied at a rate of approximately 200 pounds per minute. The maximum load was recorded Tests 9 and 10 Impact strength at 7 2' to 76" F and at -65' to 7 0* F . j. --The impact specimens were tested m a pendulum type lm pai t machine having a 30 foot pound head The specimen was held firmly in place to the base of the machine as required by the Air Force Spe< ifi< ntion 14164. The position of the specimen was adjusted so that the flat striking surface of the head struck the 1 square inch block at a point 1 inch above the bond line ard so that the pendulum was at its maximum velocity at time of impact. The energies absorbed from the swinging pendulum in causing the specimens to fail were computed from calibrations for the test machine. Tests 11 throu gh 16 Shear strengt h after exposure to salt water spray and fluid immersion £. The l/2 inch lap joint specimens were exposed as i - 3/ 4 inch wide test panels to the following conditions Report No. 1836 10 Test 11 • - 30 -day -exposure to salt-water spray (Federal Specifica- tion QQ •■ M-151). Test 12 - 30 -day -immersion in tap water. Test 13 -- 7-day immersion in ethylene glycol (Military Specifica- tion MIL -E- 5559). Test 14 -- 7 -day-immersion in anti-icing fluid (Military Specifica- tion MIL-F 5566). Test 15 -- 7 -day-immersion in hydraulic oil (Military Specification MIL-0-5606). Test 16 -- 7~day = immersion in hydrocarbon fluid (Military Specifica- tion MIL- H 3136, type III). These panels were then cut into individual test specimens, and the shear strength of the specimens was determined at 72° to 76® F. as in test 1. The shear strength of the control specimens cut from each of the bond panels before exposure was also determined in this same manner. All joint specimens prepared in this study were measured before testing for adhesive-film thickness with a measuring microscope. After the tests, all specimens were examined, and the percentages of bond failure in adhesion to metal, cohesion of the adhesive, and other types of failures were estimated. Results and Discussion The average results of the shear tests made at -65° to =70* F. , at 72 to 76® F. , and at 178° to 182* F. ; the fatigue tests made at -65° to -70° F. and at 72° to 76° F. ; and the long-time loading tests made at 72° to 76® F. and at 178° to 182 s F. are summarized in table 2. The average results of the impact tests at 72 s to 76® F. and at -65® to -70 s F. , the bend tests at 72° to 76® F. , and the shear tests made at 72® to 76® F. after salt-water spray and immersion exposures are summarized in table 2a. ■ Report No. 1836 =11 Shear S trengt h The adhesives tested in this study met the shear strength requirements of the Air Force Specification No. 14164 with the exception of adhesive 25 26 in the low-temperature | -65° to -70* F. ) shear test and adhesive 38 in the elevated temperature 178° to 182* F. ) shear test. Adhesive 25 26 can for all practical purposes also be considered to meet the shear strength requirements at 65" to -70'' F 2, 500 pounds per square inch)) because the bond strength values for the l/2 inch lap joints bonded with this adhesive process averaged close 2, 414 pounds per square Inch) to the specification requirement The 3/8 inch lap joints bonded with adhesive 25 26 that were tested in shear at -65* to 70* F or at 72 r to 76* F as controls for the fatigue tests table 2, test conditions 4 and 51 showed a higher average bond strength at the low temperature, even with some individual specimens having low bond strength values than at 72° to 76* F. There was poor correlation between shear test results obtained on these l/2- and 3/8 inch lap mts bonded with adhesive 25 26 and tested at -65* to 70* F. , but s as discussed later under fatigue tests this adhesive process and also adhesive 25 appear to have a strength transition temperature near 70* F. This strength transition near 70 f F for the adhesive 25 26 may account for the inconsistent results obtained when shear tests are made on this adhesive at 65* to -70* F The elevated temperature shear strength results obtained with adhe sive .>8 run 2. averaged so close 1,166 pounds per square inch) to the specification requirement 1, 250 pounds per square inch' that this adhesive along with all of the other adhesives tested in this study can probably be considered to meet the shear strength requirements of the Air Force Specification No 14164 Two '.or.ditions required for conducting the shear tests in this specifica tion deserve some further consideration and possible modification. The loading rate of 600 to 700 pounds per square inch per minute 300 to 350 pounds per one half square inch per minute* is considerably slower 1 1 .1 r. is the usual practice in much of the routine testing of such lap joints in various plants and laboratories T t is known that faster rates of loading will give somewhat higher failing loads in this tes' and some of the high shear values reported by other laboratories for some of these same adhesives were obtained when faster rates of loading were used than presc ribed in the specification It would seem that a rate of 600 to 700 pounds per minute on the 1/2 -square inch specimen would be reason^ k were being tested in fatigue at 72* to 76* F. , it was necessary to monitor frequently the test machine during the tests at the high stresses to compensate for the yield of the adhesive bonds With the one adhesive adhesive 37), a number of specimens failed by a continuous yielding at the high stress levels before the fatigue machine could be initially adjusted ar.d the cyclic loading started A different phenomenon was observed during the testing of two cf the other adhesives adhesives 25 and 25 26 Some of the specimens being tested in fatigue at 65° to 70" F failed while being adjusted with 40 to 70 percent of static strength before the cyclic loading could be started. These failures were in adhesion and frequently the adhesive separated from both faying surfaces of the lap joint Other specimens from this ne group that did not fail during the initial adjustment gave test points that appeared to be a reliable indication of the fatigue characteristics for these adhesives Because there were only a limited number of -Adhesives 33 and 35 are reported to be the same adhes ve formulation prepared by different manufacturer- Report No. 1836 14 specimens that did not fail prematurely in the fatigue tests at -65* to -70® F. , the fatigue curves for adhesives 25 and 25-26 at 65* to 70® p must be considered as only approximations. In static shear strength tests made for the Air Force at temperatures from 75® to -130® F. on lap-joint aluminum specimens bonded with adhesive 25 this adhesive displayed a strength- transition temperature near -70® F. , and at -80® F. the strength was less than one-third of the strength at 65® F. Similar static shear strength tests over the range from 75® to -130® F„ have not been made on the other adhesives, This change in strength near -70° F. for adhesive 25 may account for some of the specimens bonded with adhesives 25 and 25-26 failing immediately when given an initial load in the fatigue machine at -65® to -70® F„ Because of the immediate failure of some of the lap-joint specimens bonded with adhesives 25 and 25-26 when given a low stress in the fatigue machine at -65® to -70® F„ , it is recommended that caution be exercised when using these two adhesives and that such temperature limitations of the other metal -bonding adhesives be similarly investigated in lap joints. When low stresses were applied to the 3/8-inch lap-joint specimens of 0. 064~inch 9 24S-T3 clad aluminum alloy bonded with the adhesives having good fatigue resistance, the failures were, in most instances, tension failures in the metal. In actual design of bonded joints, it would be normal practice to have the ratio of overlap to the thickness of metal greater than used in this fatigue specimen. In practically all instances when two sheets of metal are to be lap jointed together with these metal- bonding adhesives, therefore, primary concern should be with the fatigue characteristics of the metal rather than of the adhesive. In making these fatigue tests, only one major change was made in the test method from that outlined in the Air Force Specification No. 14164. This specification states that the cyclic load applied to the specimen shall be tensile and shall vary from the maximum selected to approxi- mately 1 percent of the maximum. In the tests for this study, the cyclic loads were varied from the maximum selected to 10 percent of that maximum in order to avoid any zero or negative stresses being applied to the specimens when there was a slight reduction in the applied load during the repeated stressing. With pin-connected fittings, any zero or negative loading would cause excessive chattering in the fittings and make it difficult to maintain proper alinement of the specimen. The Air Force Specification No. 14164 does not state the distance from the ends of the test grips to the lap of the joint that should be used in making fatigue tests on these aluminum lap joints. It is believed that Report No. 1836 -15 this dimension should be standardized. It was found in some explora- tory tests with specimens bonded with a phenol -butyral resin formu- Otl that distanc es of l/Z 1 and 2 inches from the ends of the grips to the lap of the joint did not affect the strength results obtained ii. Btati< tests but that in fatigue tests at 72* to 76* F. , a 2 uu h dist^r.i e resulted in a lower number cf c y les to failure at a particular stress level than did distances cf 1/2 or 1 inch A distance of 1 inch was therefore used for all fatigue tests made in this study, and this distance is believed to be suitable for use in any revisions of this test method. Lcr .g t ime loa d Str ength The individual test da»a for the long-time leading tests are given in tables 21 through 30 with the graphical representation of these data presented in figures 26 through ii The relationship between the stress applied in pounds per square inch and the time to failure is shown in these figures as the smooth curve through the points of mini- mum stress The values for strength in long time -loading deter mined as required by the Air Force Specification as the stress at which the turves intersect the 2^0 hour ordinate are summarized m table 2. The long time loading tests made on the adhesives included in this study showed that at 72° to 76" F . one adhesive adhesive 38^ approached < losely the strength requiremer t of 1. 600 pounds per square inch .with an average value of 1, 590 pounds per square inch) and that all of the other adhesives exceeded this requirement in several cases by wide margins Measurements made ?s required ir. the spe if ic -Uion, to determine the amount of defer mat ion d cur r ing n the specimens that did net fail in 200 hours of loading at 72 c to 76* F. showed that bonds made with adhesives 36 37, and 38 displayed c onsiderable deformation, or >reep from 0. 0144 to 0308 inch when under load and 0. 0105 to 0. 0186 inch after unlcrdn.gV Adhesives 25 and 25 26 also shewed about the same amount of deformation while Mil: ur.der lead at 72° to 76* F. , but the permanent deformation (ob- served after unloading) was approximately half of that under load and thus much less than for adhesives j6 il and 38. Paragraph 4 3 3 6 cf the specification states that specimens whi< h are not failed in 200 hours shall in that time deform no more than an amount equal to twice the thn.kr.ess of the adhesive film This would seem to refer to deformation under load rather than to deformation after recovery. On this basis, adhesives 25, 25-26 36 37 38 run 2* would fail to meet this requirement Peport No 1836 16 In the long time load strength tests at 178" to 182* F , only four of the nine adhesives evaluated in this study met the specification requirement of 800 pounds for 200 hours or longer One of the adhesives adhesive 34) that failed to meet this requirement had a long-time strength (720 pounds) that was only slightly less than that required by the specification, but adhesives 36, 37, 38, and 41 had strength values that were only about one half of that required by the specification. These long • time loading tests appear to be a suitable means for eval uating this property of the metal -bonding adhesives, There is some question of the validity of the present limitation on the amount of de- formation under load during the 200-hour period at 72® to 76® F. with respect to the bond thickness. The present requirement specifies that this deformation under load shall not be more than twice the bond thickness. It is quite possible that two adhesives may both meet the strength requirement of 1, 600 pounds per square inch after 200 hours of loading at 7 2® to 76 s F„ One adhesive may barely meet the load requirement and in doing so not undergo much deformation The other adhesive may withstand loading of 2, 400 pounds or more for 200 hours and, in supporting this heavier load, may suffer somewhat more deformation than is currently permitted If the test were run so that only 1, 600 pounds was applied, however, this adhesive might deform very slightly under load and meet the requirement. The present deformation requirement, which neglects the actual magni- tude of the load at 200 hours, thus penalizes the higher-strength adhe- sives Consideration might be given to specifying that deformation be measured only on specimens loaded with 1, 600 pounds per square inch for 200 hours at 72° to 76® F, Consideration might also be given to evaluation of the deformation after the load is removed in addition to, or in place of, the deformation under load, For production or control testing of these adhesives* the method of testing strength in long-time loading could probably be simplified by merely applying the load required by the specification to a limited number of specimens and then noting if the bonds would withstand 200 hours of loading without failure. Beam Bend Strength in Lap joint Specimen The beam bend strength of all adhesives tested met the requirement of Air Force Specification No. 14164 of 150 pounds for this test It was found in exploratory tests that the exact centering of the loading block over the center of the lap was important in order to obtain reproducible results. Report No. 1836 -17- I mpac t S tr ength Of the r.ir.e adhesives tested or.ly one adhesive 34) met the room- and low-temperature impact strength requirements of Air Force Spe> if n aticr No. 14164 and it did this by a good margin. Adhe - sives 35 and 36 met the requirement for impact at 72* to 76* F but not at 65* to 70° F. The low temperature impact strength values of adhesives 25 and 25 26 were Lr.usually low and considerably lower than those of other adhesives tested Con' lusions The nine adhesives evaluated in this study, in general, met the shear strength requirements at the three test temperatures after exposure to salt water spray and after immersion m water and aircraft fluids. One or two exceptions were noted in certain tests No change seems necessary in the specified strength requirements for these tests, but consideration should be given to increasing the rate of load for the shear test and to more definitely stating the length of period to be used for conditioning the specimens before the shear tests at 65° to -70* F and at 178* to 182' F. Only two of the nine adhesives evaluated failed to meet the require- ments for fatigue strength at 72* to 76 F and all of the adhesives met the requirements for fatigue strength at 65' to -70 1 F It is recommended that the present strength requirements for these tests be retained Test ioads applied should be from the maximum selected to 10 percent of that maximum, and the distance from the test grip to the end of the lap should be specified as 1 inch These conditions re used in the present study Consideration should also be given to eliminating the expensive t itigue test at 65° to -70' F , as the fatigue strength at low tempera tures. determined by the present method, exceeded the fatigue strength ot 72° to 76* F. for adhesives evaluated, and in most instances the specimens tested at 65* to -70* F failed in the metal when the applied stresses were low Failure m the metal was also roted in some fitigue tests at 72* to 76° F. , and it mav be necessary to shorten the overlap in order to obtain all failures m the adhesive bor d Five of the nine adhesives tested did not meet the requirement for strength in long time loading at 178 to 182* F All of the adhesives Report No 1836 18 met the strength requirements for the Jong time-load test at 72° to 76° F , but five of the adhesives showed a greater deformation in the adhesive bond during 200 hours at 72* to 76* F than is permitted by Air Force Specification 14164. The deformation permitted during the long-time -load tests should be modified so as not to penalize adhesives having high strength in long time loading It is also possible that the requirements for qualifying adhesives by the long - time -load tests could be simplified by running only a limited number of tests at a single specified load, such as 800 pounds per square inch for a standard time period, such as 200 hours, and noting failure or absence of failure after this period All of the adhesives tested met the bending strength requirements of the spec ific aticn Only one of the nine adhesives tested met the requirement for impact strength at both 72* to 76 s F and at -65° to -70° F. The values ob tained in this test seem to depend greatly on the method of holding the test specimens; and it is doubtful if the present method is reproducible to the extent required for this spe ific -ition Report No 1836 -19 . •p -P U| 3 m CO •C! ON O CO *J ON O O c 2 o CVJ •H CD i W) CVJ CD 1 ? 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43 °H CO CQ 13 O o 43 CO CO 00 H to to ^t- CD CD H > OJ > •H •H •H co q CO Cj CO CD p i 3 B c H m P a d •i-t o #j H d G ^ III 3 C3 *■• bd H H a) H ilAi l I o z (10 million cycles) Control strength! W5° to -70° F. ) 6. Standard-temperature (72° to 76" F.) long-time etrength£>z 200 hr. 10 hr. 1 hr. 7. Elevated-temperature (178« to 182" F.) , long-time etrengtbS'- 200 hr. 10 hr. 1 hr. 2,500 1,250 2,500 650 650 Test results— for Adheelve 25 P. 3.1. 3,236 65-6.4-27196-5.0-27 Adhesive a 25 and 26 P. 9.1. 3,382 1,600 800 £l,959 94-5.1-9 £4,442 18-4.7-6 11.325 3,405 66-7.6-12 11,150 . 4 835 l23-(2.)-12 1,975 2,035 2,210 1,000 1,050 1,450 ^2,009 97-5.7-9 £2,414 8-6.1-6 ll,240 2,966 93-4.5-12 ll,075 3,957 17- (£H2 2,180 2,350 2,495 1,185 1,310 1,495 Adhesive 33 P. 3.1. Adheelve SAdheslve 3* : 35 4,561 86-2.9-27 4,230 76-3.4-27 £4,025 ! 5l,304 73-2.9-9 : 99-3. 7-9 £3,292 11-2.9-6 470 5,187 92-3.3-12 675 3,909 15-3.3-12 3,680 3,705 3,750 1,620 1,720 1,805 £3,466 100-3.7-6 770 4,263 85-4.5-12 ll,240 j 3,898 80-3.0-27 ^3, 406 94-2.9-9 £2,758 72-3.0-6 -500 4,132 81-5.3-12 850 4 261 96-4.4-12 3,300 3,390 3,510 720 725 760 2,799 42-5.3-11 3,680 3,705 3,750 1,560 1,640 1,805 Adhesive 36 P. 3.1. 3,442 86-3.6-27 5.1,600 81-4.4-9 £4,946 23-4.0-6 685 3,806 79-5.9-10 ll,095 5,477 33-5.8-10 2,140 2,290 2,595 400 575 790 Adhesive :Adheslve 37 : 38 (Run 1) 3,555 92-5.8-27 ■Si, 516 69-5.3-9 £5,090 57-5.6-6 735 3,511 96-5.9-12 Il,180 5,363 90-6.0-12 2,050 2,260 2,700 430 630 910 2,496 83-r7.3-27 .5.934 30-7.6-9 £2,486 69-8.2-6 840 2,716 76-6.5-10 3,179 76-7.7-10 1,590 1,665 1,850 390 435 530 Adhesive 41 P.s.l. 1 P.e.l. Adheelve : 38 : (Run 2) : '■ 2,679 79-10. 3-57! 97-5. 3-27 £l,l66 81-8.4-9 £3,302 98-8.1-6 830 3,578 £l,668 45-6.3-8 £2,509 98-6.8-6 1,100 2,681 ! 4,316 72-9.1-12 11,350 3,723 100-9.0-12:97-5.3-12 1,590 1,680 1,975 350 550 780 99-6.0-12 1,100 2,950 2,990 3,190 3,450 310 550 1,010 •=Theae results were obtained on lap-joint specimens fabricated under the bonding conditions described In table 1. The first values given are the shear strength results. Listed underneath the shear strength results are: First, the estimated percentage of cohesion failure In the adhesive; second, the adhesive film thickness In mils; and third, the number of specimens averaged In the result. The rate of loading for teats 1, 2, and 3 and the control tests for tests 4 and 5 was 600 pounds per square Inch per minute. ^Test results obtained with a 1/2-lnch overlap speolraen. ^Teat results obtained with a 3/8-lnch overlap apeolmen. —Values are taken from smooth curvea drawn through the minimum-strength values. ^Bonded Joints teated approximately 10 minutes after being placed In teat chamber at desired temperature. £lJonded Joints tested approximately 30 minutes after being placed In test chamber at desired temperature. iFallures at or near this streaa were tension failures of the metal. 8 -Values obtained from a limited number of tests made to confirm test data obtained for this adhesive In a previous study for the Wright Air Development Center. Q i-Thlckneaa of film was not observed. 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H Jt a o o £ H *j £ « 3 a. a co c t. a c t. h i a. o £ H o i a. * a. 3 h o a hoi c -a c a a *> ana a £ a > a 3 > a tj o h q o - w a. a 1 o &o a a • a 3 a a a c h c a *> h a o h a > a B TJ a o woe a o a a, 3 a a a. o an a a a a. *• o a 3 c a X a o h o a c . - ■ 3 r\ a £ h h a o - I i. s > 0J > E -j a - • a c a m £ h H O *> — a 1 — c h £r~v o a a »- I o c c r-\ a. a a a. a O C C £ O a. * o o vac c li h a. a E a O a «-■ a o- a I a tj h o a h a a e > a tj a o c a a *> i «j a • e a a a a -. e tj > H o h c a. a ** 3 a a o c a a o a a. a I £ jj Table 3c — Summary of individual results of fatigue tests at room t emper at-ure of lap-joint specimens bonded wi th adhe sive 25- Specimens Control s Ifeximum re- s Noo g strength— s peated stresses f oSolo PoSoio sPercent: Cycles to sCohesionsAdhesionsAdhesive- faiiure s failure : failure s film s s sthickness s Percent s Percent s Inch e o • o s of s s controls o o 000 • 000 O O 000 25-10-2 3 4 25-11-7 8 9 e c o o o • a • 3,520 3,520 3,520 3,210 3,210 3,210 • • o © o o o o • o a 2,460 1,410 1,935 2,250 1,280 1,765 o • o o o 70 40 55 70 40 55 • O • O O o • O • e o 19,500 21,587,900 258,900 39,000 6,521,700 508,100 s 95 s 5 s s Specimen did not? s fail s s Tension failure s s in metal s 000 95 5 s Tension failure s 8 in metal § OOOOOOOO QO OOOOOOOOo 0o0066 o0056 00056 o0086 .0089 o0082 25-12-2 3 4 o o o o 3,260 3,260 3,260 o 1,960 980 2,120 • o e o o 60 30 65 o o 232,300 22,169,800 39,300 000 OOOOOOOO Q.O OOOOOOOOo s Specimen did nots g fail s s 95 s 5 s 0OO87 0OO83 c0089 25-13-7 8 9 o o o c o o 3,710 3,710 3,710 2,230 i,no 2,410 o o o 60 30 65 o o 35,200 27,234,900 14,800 000 g 95 s 5 s g Specimen did nots s fail g 8 100 8 8 o0070 o0071 0073 25-14-2 3 4 o o o o • o o 3,420 3,420 3,420 c e • 1,710 1,540 2,565 o o a o o o o 50 45 75 • e 470,000 1,441,500 2,900 % Tension failure s s in metal s oOOOOOOO CIO OOOOOOOO* 8 100 1 % 0OO8I o0079 0OO8I 25-15-7 8 9 o • 3,310 3,310 3,310 • o o 1,655 1,480 2,480 e o • • • 50 45 75 473,100 1,813,400 3,600 000 s Tension failure 8 s in metal 8 ocoocccg QO ©eoooceoo 8 100 8 8 o0077 ,0076 o0076 -Tests were made in an axial-loading fatigue machine at a rate of 900 cycles per minute o Tension loading produced shear stresses in single -lap speci- mens* The 1-inch-wide specimens were made from 0064-inch, 24S-T3 clad aluminum alloy with a 3/8-inch. lap ^Control-strength values are the average shear strength at 72® to 76 8 Fo for two test specimens cut from the same panel as the fatigue-test specimens The control specimens were the 2 outside specimens and the fatigue specimens the 3 center specimens in a group of 5 specimens, ^Minimum repeated stress for each cycle of loading was 10 percent of the maximum for that cycle o Report Noo I836 Table 4. — Summary of individual results of fatig ue tests at -65 to -70* y, o f lap-joint specimens bondi d with adhe i "_■__ \ - specimen; :. T o 25-10-7 8 9 25-11-2 3 4 25-12-7 8 25-13 25 -14 -7 8 25-15 Control strength- P.s i 4,950 4,950 4,950 4,920 4,920 4,920 4,630 4,630 4,630 5,410 5,410 5,410 5,620 5,620 5,620 4,470 4,470 4,470 "aximum re- , peated stress* P.s 1 Percent? of controls 3,465 1,980 1,240 70 : 40 : 25 ! 3,445 1,970 1,230 70 ! 40 1 25 2,780 1,390 1,390 60 '% \ 30 : i 30 : 3,245 1,625 ! 60 \ > 30 : 2,705 50 : 2,810 2,250 2,250 I 50 40 J ; 40 ! 2,235 1,115 i 50 : 25 s 2,680 ; 60 : Cycles to - Cohesion; Adhesion. Adhesive - failure -failure ; failure J film : 1 thickness ; Per cent 'Percent • Inch * 157,000 5,886,600 c • O • • s 100 100 Tension failure in metal • ■ 0073 o0071 0074 k k 2,941,200 • • c s 100 g 100 Tension failure in metal • 0092 0080 00 84 40,600 1,100 3,197,800 n 35 65 s 100 Tension failure in metal • .0082 0083 0085 k 1,051,800 16,500 • ■ D s 100 Tension failure in metal 30 s 70 c 0072 0065 0067 , 9.700 L ° a O • 40 $ 60 100 s 100 0079 0074 0074 It 20,031,600 • O O • s 100 Specimen did not; fail s s 100 007/. 0079 0077 =Tests were made in an axial -loading fatigue machine at a rate of 900 cycles per minute , Tension loading produced shear stresses in single-lap speci mens. The 1 -inch-wide specimens were made from 064-mch 243-T3 clad aluminum alloy with a 3/8 -inch lap ^Control -strength values are the average shear strength at -65 to -70 F for two test specimens cut from the same panel as the fatigue -test speci- mens. The control specimens were the 2 outside specimens and I fatigue specimens the 3 center specimens in a group of 5 specimens «-!'.inimum repeated stress for each cycle of loading was 10 percent of the maximum for that cycle « Specimen failed while load was being adjusted Report No. I836 .'.mmar y of individual r esults of fatigue tests at room tempera - ure o f lap-joint specimens b onded with a dhesive 25 ■ < ' h Specimeng Control g Maximum re- „s Cycles to g Cohesion "Adhesions Adhesive - Noo % strength- s peated stresses failure s failure % failure g film m " x oS old roSol' 2 Percent? 2 Percent s Percent s ch • of ■ 000 • s controls 000 000 % 000 • 26-10-2 % 2,815 1*970 % 70 g 73 9 900 s 100 g sr 0o0039 3 * 2,815 1,125 40 8 25,390,500 g Specimen did not° g fail g 0OO42 4 2,815 • 1,210 43 ' 20,447,400 OOOOOOOO CLO OOOOOOOOo 000 oOOiO 26-11-7 2,980 • 2,980 g 70 1,700 000 g 100 2 g o0050 8 • 2,980 1,190 40 23,783,500 g Specimen did notg g fail g 0048 9 ' 2,980 ! 2,085 • 70 • 201,600 s 100 g g ,0047 26-12-2 2,980 » 1,790 • 60 267,600 • g 100 g g o00 3 e 2,980 • 895 30 « 23,656,900 2 Specimen did not 2 2 fail g 00046 4 2,980 • 1,280 8 43 2,650,300 g Tension failure s g in metal g 00^6 26-13-7 % 2,905 g 1,740 • 60 1 205,500 g 100 g g o0060 8 2,905 ' 870 30 20,305,300 g Specimen did not? g fail g 0050 9 2,905 1,305 45 2,040,100 g Tension failure § g in metal g 000 000 C.0052 26-14-2 3,155 s 1,580 50 666,300 0QO0 oeoooooo o0045 3 » 3,155 1,357 43 g 936,300 OOOOOOOO CLO OOOOOOOOo c0044 4 O 3,155 O 1,295 e 41 25,543,200 s Specimen did nois § fail g 000 • c0043 26-15-7 • e 2,965 1 1,480 50 718,200 g Tension failure g g in metal g , OOaO 8 2,965 I 1,335 a 45 1,963,800 • OGOOOOO CLO OOCOCOOOe 0OO4I 9 c 2,965 J 2,075 70 14,400 g 100 g g o0041 iTests were made in an axial-loading fatigue machine at the rate of 900 cy- cles per minute o Tension loading produced shear stresses in single-lap specimens.. The 1-inch-wide specimens were made from 0064-inch 24S-T3 clad aluminum alloy with a 3/8-inch lap Q —Control-strength values are the average shear strength at 72® to 76° Fo for 2 test specimens cut from the same panel as the fatigue-test speci- mens® The control specimens were the 2 outside specimens and the fatigue specimens the 3 center specimens in a group of 5 specimens o ^Minimum repeated stress for each cycle of loading was 10 percent of the maximum for that cycle o Report Noo I836 Table 6. - -Summary i Df individual results of fatieue tests at -6 to 25- 26 1 -70" F i of lap-.noint specimens bonded with adhe< >ive Specimen: Control, •.aximum re- : strength": peated stre: • • * : PoSoi. : P. Sci-: Percent ; Jycles to j Cohesion; Adhesion: Adhesive- failure : failure : failure : film : : tthickness : Percent .Percent Inch • • • -10-7 : 8 : 9 • • ^5,070 45,070 J70 • • • ■ • • • • 3,550 2,030 1,265 :c • • • of ontrc e © Ls • a • • 4. 7 49,700 • 1 A O O • • 15 : 85 10 s 90 Tension failure m metal • • • • ■ • • 26- 70 40 25 0050 .0041 0046 26- • -11-2 : 3 : 4,780 4,780 • c 3,345 1,915 • • • 70 40 m • • • 10 s 10 s 90 90 • • .0044 0045 26- 9 -12-7 : 8 : 9 ! 4,950 4,950 4,950 * c 2,970 1,485 1,980 « • 60 30 40 • • e 7,000 4,650,400 2,300 • • e • 10 1 90 Tension failure in metal 10 s 90 e 0051 .0048 -0053 26-13-2 I 3 : 4 I 54,890 |J4, 890 5 4, 890 • 2,935 2,445 1,955 • c 60 50 40 • c 9,900 • e t • • 10 20 s 15 : 90 80 85 • • • .0057 c0056 0059 26-14-7 I 8 ! 9 I 4 4,910 ^4,910 ^4,910 • • 2,455 980 2,945 • • • • 50 20 60 • • 28,200 20,230,800 • • 20 80 i Specimen did nots fail : 10 s 90 0058 -0055 .0058 26 -15-2 : 3 : 4 1 4,320 4,320 4,820 • • • • 2,410 965 1,445 • • 50 20 30 • • • • • 20,120,600 4,602,100 • * • • • e 15 : 85 5 Specimen did not? fail s Tension failure : In metal 1 0055 0056 .0052 Tests were made in an axial -loading fatigue machine at the rate of 900 cy- cles per minute c Tension loading produced shear stresses in single-lap specimens. The 1 -inch -.ale specimens v/ere made from 0.064-inch 243-T3 clad aluminum alloy with a 3/S-inch lap. Control-strength values are the average shear strength at -65° to -70* F. for 2 test specimens cut from the same panel as the fatigue-test speci- mens. The control specimens v/ere the 2 outside specimens and the fatigue specimens the 3 center specimens in a group of 5 specimen liniraum repeated stress for each cycle of loading was 10 percent of the maximum for that cycle. ^Control trength based on only one test. 2The average of satisfactory controls in other panels was used as the con- trol strength, because the controls for this panel were low and erratic Report ' T o 1836 Table 7* — Summary of individual re sults of fatigue tests at room temperature of lap-joint specimens bonded with adhes ive 33 - Specimens Control^? Maximum re- '< Noo s strength— s peated stresses Cycles to sGohesionsAdhesions Adhesive- failure s failure s failure % film % s sthickness roSulc PoSoio s Percent s i Percent ^Percent Inch • • • e • s of : : control s • 33- -10-2 3 4 • • 5*000 5,000 5,000 • 3,500 2,000 750 • 70 40 15 e « o o 300 5,000 410,000 • 60 20 15 • e 40 80 85 Or. 0029 .0025 ,0027 33- -11-7 8 9 • 5,355 5,355 5,355 '• 3,750 2,140 805 70 40 15 100 2,000 260,400 * 25 20 5 75 80 95 ,0032 • 0034 .0030 33- -12-2 3 4 o 5,135 5,135 5,135 • • 3,080 1,540 515 o 60 30 10 o 200 13,600 2,563,600 5 20 20 « 95 80 80 o0031 .0030 o0030 33-13-7 8 9 * • • e e 5,200 5,200 5,200 o 3,120 1,560 520 60 30 10 200 10,000 2,636,900 c 35 20 30 V 65 80 '70 c o0033 .0032 o0030 33-14-2 3 4 • • a i e 5,120 5,120 5,120 • c © 2,560 1,025 410 © o 50 20 8 c o 900 68,900 20,609,700 20 5 s Specimen fail 80 2 95 s did not? • ,0034 .0037 c0031 33-15-7 8 9 • o o • 5,310 5,310 5,310 ■ o 2,655 1,060 425 o o o 50 20 8 c D o 800 69,900 20,609,700 30 i 10 s Specimen fail 70 90 s did nots c o0034 c0037 o0030 -Tests were made in an axial-loading fatigue machine at the rate of 900 cy- cles per minute c Tension loading produced shear stresses in single-lap specimens., The 1 -inch-wide specimens were made from Co 064-inch 24S-T3 clad aluminum alloy with a 3/8-inch lap c ^Control-strength values are the average shear strength at 72° to 76 * Fo for 2 test specimens cut from the same panel as the fatigue-test speci- menso The control specimens were the 2 outside specimens and the fatigue specimens the 3 center specimens in a group of 5 specimens e ^■Minimum repeated stress for each cycle of loading was 10 percent of the maximum for that cycle c Report- Noo I836 Table 8 — Summary of individual results of fatigue tests at -65* to of lap-joint specimens bonded with adhesive 33l Specimen No. i Control : .strength—? Ps.i. : 33-10-7 8 ■ 9 4,000 : z.,000 . 4,000 . 33-H-2 : 3 i 4 3,815 . 3,815 I 3,815 : 33-12-7 : 8 : 9 i 4,190 : 4,190 : 4,190 : 33-13-2 : 3 i 4 i 4,055 : 4,055 : 4,055 : 33-14-7 i 8 i 3,800 : 3,800 : 33-15-2 ! 3 I 3,570 : 3,570 : "aximum re- «l peated stress^. P.S 1. i Percent: : of -. : control o 2,800 1,600 720 I 70 . . 40 : - 18 : 2,670 1,525 955 I 70 I 1 40 : l 25 s 2,515 1,255 1,050 \ 60 i I 30 : ; 25 : 2,435 1,215 730 : 60 : i 30 : ! 18 : 1,900 760 : 50 - 20 : 1,785 715 ■ 50 . . 20 s Cycles to failure Cohesion : Adhesion l Adhesive- failure .failure : film t ?thickness Percent .Percent ; Inch • 3,500 : 30 • 70 0-0033 125,200 : 20 • 80 0036 7,082,300 : 15 85 0032 ■ o 4 1 : 5 e 95 • ,0033 101,700 : 5 95 • 0033 1,167,300 : 10 • 90 • ,0031 8,400 : 15 e 85 .0029 493,000 i 10 • 90 • o0031 1,903,800 : 10 • 90 • ,0022 1,000 : 10 e O • 90 • 0036 404,400 : 5 • 95 s .0032 4,432,000 : 20 O • 80 • 0032 39,900 ! 10 • 90 • .0032 20,168,200 : Specimen did not : c0029 c fail • 73,400 ! 10 O B 90 0035 4,052,600 : 15 O 85 5 .0030 -Tests were made in an axial-loading fatigue machine at the rate of 900 cy- cles per minute- Tension loading produced shear stresses in single -lap specimens The 1 -inch-wide specimens were made from 064-inch 24S-T3 clad aluminum alloy with a 3/8-inch lap ^Control -strength values are the average shear strength at 72" to 76* F. for 2 test specimens cut from the same panel as the fatigue-test speci- mens ■ The control specimens were the 2 outside specimens and the fatigue specimens the 3 center specimens in a group of 5 specimens, ^Minimum repeated stress for each cycle of loading was 10 percent of the maximum for that cycle- Specimen failed during first application of load Report No I836 Table 9. — -Summary of indivi dual results of fatigue tests at room temperature of lap-joint specimens bonded with adhesive 34~ Specimen: Control % Itexiraum re- ~: Noo : strength-: peated stresses Cycles to :Cohesion:AdhesiomAdhesive- failure : failure : failure s film : s sthickness $ r« s © 1 © • roSoie e x ©re cni* i s Percent : Percent Inch • • o • o o o • o • o e 4,280 4,280 4,280 o o o c • 3,000 1,710 840 :c of ontro Is o • o 2 S 800 s 72,700 : 4,787,200 g 85 95 95 • • • 15 5 5 « 34-10-2 3 4 70 40 19o5 0,0044 o0050 o0051 34-H-7 8 9 • o 4,210 4,210 4,210 • 2,950 1,685 675 » 70 40 16 • o o • 3,600 s 68,600 : 35,702,000 % o 80 95 Specim< fail • 3n • 20 s 5 s did not: .0045 e0046 ,0048 34-12-2 3 4 • o • • o • 4,660 4,660 4,660 o o o 2,800 1,400 840 • • • 60 30 18 o • • 5,400 s 273,000 g 6,149,600 s 95 95 95 • e 5 5 5 • • • u0038 0OO38 0OO43 34-13-7 8 9 • 3,980 3,980 3,980 ■ • 2,390 1,195 715 o c 60 30 18 • • o 3,500 % 276,800 % 11,857,100 s 95 95 100 ° 5 5 • • 0OO52 0OO48 o0049 34-14-2 3 4 • o « « • o • 4,710 4,710 4,710 • e • © 2,355 1,180 755 • • • • o • • 50 25 16 • • 20,800 s 576,200 s 6,791,000 : 100 s 100 s Tension failure in metal • • • o0026 o0033 .0036 34-15-7 8 9 o • « o • 9 3,740 3,740 3,740 • ■ 1,870 935 600 • 50 25 16 • • 45,300 s 969,600 : 40,206,600 ! 100 s 100 : Specimen fail • s : did not: o0055 „0079 ,,0068 —Tests were made in an axial -loading fatigue machine at a rate of 900 cycles per minute o Tension loading produced shear stresses in single-lap speci- mens c The 1-inch-wide specimens were made from 0o 064-inch, 24S-T3 clad aluminum alloy with a 3/8-inch lap e 2 -Control -strength values are the average shear strength at 72° to 76 s Fo for 2 test specimens cut from the same panel as the fatigue-test specimens c The control specimens were the 2 outside specimens and the fatigue speci- mens the 3 center specimens in a group of 5 specimens c ^Minimum repeated stress for each cycle of loading was 10 percent of the maximum for that cycle Report No* I836 Table . irv o: ■_ - • of fatigue tests at -65° to -' /' 3 . . of 2.-.ip-/nint specimens bonded with adhesive 3kL 34-13-2 3 34-14-7 8 34-15-2 3 Specimen : Control . ■strength— P.S.I. 34-10-7 8 : 9 ! i 3,640 : 3,640 i 3,640 34-11-2 : 3 ! 4,055 : 4,055 4 : 4,055 34-12-7 i 8 ; 4,695 4,695 4,695 4,410 4,410 4,410 4,365 4,365 4,365 4,390 4,390 4,390 i-aximum re- : peated stress^-: P.s .1. [Percent: : of : 5 control; 2,550 1,455 1,640 : 70 : i 40 : i 45 : 2,835 1,620 : 70 : : .. : 1,325 : 45 : 2,815 1,410 ! 60 I : 30 : 1,380 : • 40 . 2,650 1,325 • - 60 ! • 30 : 1,765 i 40 : 2,180 : 1,530 : 50 : 35 : 1,090 : 25 : 2,195 ! 1,535 50 35 : 1,095 : . 25 1 Cycles to failure 4,300 1,631,500 970,200 1,900 2,659,000 319,300 9,700 4,927,100 1,010,200 12,300 11,940,400 901,500 99,900 1,296,200 20,749,000 49,800 2,664,100 20,230,000 Cohesion ;Adhesion failure : failure Percent . Percent 50 1 : 50 80 i 20 75 l : 25 60 I 40 Tension failure in metal 95 : 5 95 5 Combination fail- ure in metal and joint 100 : 90 : 10 Tension failure in metal 95 : 5 • 100 : Tension failure in metal Specimen did not fail • 60 j 40 Tension failure in metal Specimen did not: fail :Adhesive- film thickness Inch 0.0050 .0051 .0044 .0043 .0043 .0042 .0045 .0048 .0047 .0035 .0038 .0043 .0037 .0033 .0033 .0047 .0044 .0052 —Tests were made in an axial-loading fatigue machine at a rate of 900 cycles per minute. Tension loading produced shear stresses in single-lap speci- mens. The 1 -inch-wide specimens were mads from 0. 064-inch 24S-T3 clad aluminum alloy with a 3/8-inch lap. -Control-strength values are the average shear strength at -65 to -70" for 2 test specimens cut from the same panel as the fatigue-test speci- mens. The control specimens were the 2 outside specimens and the fatigue specimens the 3 center specimens in a group of 5 specimens. ^ilinimum repeated stress for each cycle of loading was 10 percent of the maximum for that cycle. Report No. I836 Table 1 1 , — Summary of individual result s of fatigu e test s at room temperature of lap-.ioint specimens bonded with adhesive 33— Specimen s Control s Maximum re- . s Cycles to s Cohesions Adhesions Adhesive- No £- : strength*^ peated stresses failure s failure s failure s film sthickness • PoSoi* • foSolc s Percent? : of s 8 Percent • si 'ercent s Inch e • • o • • • j control: • • % 2 ; % • AF-35-1-2; 4,850 s 3,510 * 72c4 s 1,300 100 • s (I) 3s 4,850 s 2,505 s 51,6 ! 4,700 100 2 ooeooooooo 5s 4,850 • 1,000 s 20,6 2 270,500 • 75 % 25 • 000000000 AF -35-2-1 s 4,945 • 3,510 • 71.0 : 1,600 90 • 10 •000000000 3.° 4,945 ■ 2,005 40 «6 s 31,300 40 t 60 • 900000009 4: 4,945 s 1,000 s 20o2 : 322,400 s 35 65 oaeoaoooo* • AF~35-3-2s 4,915 £ 3,510 • 71=4 s 800 2 100 eooooeoooo 4s 4,915 2,005 • 40,8 s 9,800 2 100 % ooeoooooo 5s 4,915 % 500 • 10.2 s 21,000,000 1 Specimen Q.XCL nOL 0000000000 % % s s i fail s % % J 2 2 % • AF-35-.4-18 5,220 % 3,005 % 57o6 s 7,600 s 90 s 10 ooooeooooo 3i 5,220 2,005 % 38„4 s 47,400 s 10 % 90 OOOOOOOOOO s « 5,220 9 500 • 9o6 : 32,636,000 s Specimen &1Q. nO U OOOCOOOOOO o o • e % fail • • « « % • AF-35-5-ls 5,140 3,005 58,4 s 4,000 s 100 s ©OOOOOOOOQ 2s 5,140 s 1,505 2933 s 31,000 i 80 20 ©ooeoooeoQ 4s 5,140 • 500 i 9o8 s 20,260,000 • Specimen CHQ nOtt Ssoooooooo • • c p « t fail • e • • • AF-35-6-2s 5,260 % 3,005 % 57 ol ? 6,900 % 60 • 40 oooo<> OOOOO 3s 5,260 % 1,505 % 28,6 : 102,300 % 60 c 40 • 090000000 5s 5,260 2 1,000 s 19,0 : 282,100 s 45 • 55 •eeooooooe • AF-35-7-18 5,240 : 2,505 . 47 »8 s 14,100 J 50 I 50 « c 0000000*0 3s 5,240 % 1,505 • 28,7 s 99,000 20 • 80 OG©09©0000 4s 5,240 ; 750 ' 14»3 s 6 2,372,400 2 30 e 70 • 000000000 • AF-35-8-2: 4,485 • 2,450 ■ 54°7 s 4,400 2 100 • 6 • OCOOCI&OOO 4s 4,485 • 1,000 • 22 ,3 s 120,500 s 100 • CW OOOOOSO 5s 4,485 s 750 16,7 s 776,800 s 100 • ooooeooooo 35-10-2 s 4,110 ■ 2,880 2 70 1,300 ■ 100 • 1 O0OO6O 3 s 4,110 • 615 s 15 : 3,633,700 • 45 • 55 : ,0054 (Sheet 1 of 2) Report Noc 183 6 Table 11 . — Summary of individual results of fatigue tests at room tem- perature of lap -joint specimens bonded with adhes i ve 35 - ( Continued) Specimen No 2 : Control . . strength^ : PoB.i : 35-11-7 8 : 4.380 ! j 4,380 i 35-12-2 J 3,570 : 35-13-7 : 4,060 : 35-14-2 : 4,430 35-15-7 V • 4,180 : Maximum re- peated stress ±: Cycles to i Cohesion i Adhesions Adhesive - failure ; failure .failure : film .thickness P.s 1. — • ; Percent . of : .control; 2,630 : 60 525 : 12 1,785 . 50 . 1,625 • 40 1,330 ! 30 : • • : Percent ; Per cent Inch 835 s 20 ; • • • • • « • • • 5,900 : 95 5 t 0053 9,043,900 s 30 i 70 : 0055 3,70C 100 6 : 0067 • 11,900 : 100 • • >0060 115,500 ; 95 • 5 0049 247,600 s 100 D ft • : , 0047 -Tests were made in an axial -loading fatigue machine at a rate of 900 cycles per minute- Tension loading produced shear stresses in single-lap speci- mens. The 1-inch-wide specimens were made from 0.064-mch, 24S-T3 clad aluminum alloy with a 3./8-inch lap ^Specimens AF-35-1-2 through AF-35-8-5 were prepared and tested under Air Force Purchase Order No (33-O38)50-1078Z Specimens 35-10-2 through 35-15-7 were tested in the present study to compare the results with those previously obtained in the Air Force project Control -strength values are the average shear strength at 72" to 76* F for 2 test specimens cut from the same panel as the fatigue -test specimens The control specimens were the 2 outside specimens and the fatigue speci- mens the 3 center specimens m a group of 5 specimens nimum repeated stress for each cycle of loading was 10 percent of the maxinrim for that cycle 5 The adhesive -film thicknesses were not measured and recorded for all of the fatigue specimens prepared with adhesive 35 in the Air Forces study, but those specimens that were measured had adhesive -film thicknesses of 0020 to 0,0025 inch (Sheet 2 of 2) Report No 1836 Table 15 » © * — SffiffiS&X -70" 7 of individual res suits of fatieue tests at -65 jecimens bonded with adhesive t Fo of laD-ioin' T Specimer Noo 18 • • o • e e • Control strength- fuStli) g Maximum re- „% -t peated stresses • Cycles to failure g( 8J O ■ 8] O }ohesior failure D ercent is; _ O ■ O 8l O O O Ldhesioi failure St • idhesive- film hickness s PoS»ioS Percent s g °. of g g g control g 'ercent Inch 35-10-7 8 9 • o 3,290 3,290 3,290 l 2,305 8 s 1,315 8 8 1,150 8 70 40 35 e 8,900 400,200 651,500 • O O 95 95 70 O O O O O 5 5 30 Oo0053 0OO56 .0055 35-H-2 3 4 o o o c o 2,420 2,420 2,420 8 1,695 8 8 970 8 8 725 8 « O • O 70 40 30 • 52,700 2,357,600 20,118,100 • • O O O O O 40 1 25 8 Specimen fail 60 75 8 did not 8 »0057 o0057 o0055 35-12-7 8 9 • • © o o 2,290 2,290 2,290 : 1,375 i 8 690 8 O O « 8 1,030 8 60 30 45 • • 208,200 20,550,000 1,875,800 • • 40 Specimen fail 30 8 60 8 did not s 70 t o0057 u 0056 o0051 35-13-2 3 4 o o o • 3,020 3,020 3,020 8 1,810 8 8 905 8 8 1,360 8 60 30 45 • 82,200 7,332,000 753,600 8 100 95 100 ■ O O 5 0OO59 o0057 .0059 35-14-7 8 9 o e 2,770 2,770 2,770 O O 8 1,385 8 8 970 8 8 1,110 8 50 35 40 272,400 3,337,800 1,574,800 • ■ O 30 20 20 • O 70 80 80 0OO46 o0049 0OO5O 35-15-2 3 4 • o e o o e o e 3,130 3,130 3,130 8 1,565 ! 8 785 s 8 1,095 8 50 25 35 ■ 216,600 20,000,000 1,299,600 100 8 Specimen fail 100 8 § did not s g 0OO46 o0049 o0049 ^Tests were made in an axial-loading fatigue machine at a rate of 900 cy- cles per minute o Tension loading produced shear stresses in single-lap specimens o The 1 -inch-wide specimens were made from o 064-inch 24S-T3 clad aluminum alloy with a 3/8-inch lapo 2 —Control-strength values are the average shear strength at -65 s to -TO 1 " Fo for 2 test specimens cut from the same panel as the fatigue-test speci- mens. The control specimens were the 2 outside specimens and the fatigue specimens the 3 center specimens in a group of 5 specimens «, ^Minimum repeated stress for each cycle of loading was 10 percent of the maximum for that cycle » Report Noo 1836 Table 13 - - Nummary o f individual results of fatigue tests at room tempe r ature of lap-joint specimens bonded with adhesiv e 36 =- Specimen: Control . Maximum re- : .strength-: peated stresses Cycles to failure 36-10-2 3 4 36-11-7 8 9 36-12-2 3 4 36-14-2 3 4 36-15-7 8 9 A. 100 4,100 4,100 3,460 3,460 3,460 3,740 3,740 3,740 3,880 3,880 3,880 3,830 3,830 3,830 P..S 1 Percent . of : control < 2,800 : 1 o 68 s 2,050 i 820 50 8 20 i 2,420 1,385 690 : 70 s i 40 : 20 : 2,245 I 1,495 560 60 °: 40 : 15 : 2,330 1,165 700 60 ! : 30 : ! 18 : 1,915 1,150 690 50 I 30 8 : 18 : 1,300 20,300 1,884,100 6,200 160,400 8,823,200 5,900 197,300 29,462,600 6,300 134,100 10,708,900 22,200 338,000 10,003,600 : Cohesion : Adhesion ; Adhesive - : failure : failure . film : : .thickness : Percent : Percent 75 85 75 80 75 85 80 90 25 15 25 20 25 15 20 10 Specimen did not fail Inch : 0.0060 ! 0056 s c0051 : 0OO46 0052 s 0OO4O : .0053 : e0076 .0071 85 75 40 85 75 80 15 s .0069 25 : -OO56 60 s 0055 15 25 20 ,0067 ,0052 ,0060 ^Tests were made in an axial -loading fatigue machine at a rate of 900 cycles per minute Tension loading produced shear stresses in single -lap speci- mens- The 1-lnch-wide specimens were made from 0,064-inch, 24S-T3 clad aluminum alloy with a 3/8 -inch lap -Control -strength values are the average shear strength at 72" to 76" F for 2 test specimens cut from the same panel as the fatigue -test specimens The control specimens were the 2 outside specimens and the fatigue speci- mens the 3 center specimens in a group of 5 specimens •^Minimum repealed stress for each cycle of loading was 10 percent of the maximum for that cycle, Report NOi 1836 Table 1 4 - — SMMLg ? f individual results of fatigue tests at -ov to -70° Fo of lap-joint specimens bonded with adhesive 36, Specimens Control s Maximum re- : Noo 8 strength 2 -^ peated stresses I o S oil Cycles to s Cohesion sAdhesion? Adhesive- failure s failure s failure t film s s sthickness Po Soi» g Percent g S Of 2 s control? j Percent s Percent Inch 36-10-7 s 8 8 9 8 o 5,470 5,470 5,470 o a « o • 3,830 2,735 1,370 o o 70 50 25 o o o o 7,100 8 11,200 8 2,633,600 8 85 s 15 85 8 15 Tension failure in metal 0o0073 o0064 o0067 36-11-2 g 3 8 4 i 5,330 5,330 5,330 o o 3,730 2,130 1,330 o o o 70 40 25 o o o o o 8,100 8 156,500 8 2,594,400 s 85 85 65 15 15 35 • .0060 0OO68 ,0058 36-12-7 s 8 s 9 8 5,230 5,230 5,230 o o o o o 3,140 2,090 2,615 o o • 60 40 50 21,100 s 146,400 8 13,500 8 75 90 90 a 25 10 10 o0059 0OO69 o0074 36-14-7 8 8 s 9 8 o o 5,720 5,720 5,720 o o o o o e o • 3,430 1,715 1,145 o o o o o 60 30 20 e o o o o o © 20,400 8 707,100 8 6,286,800 s 70 8 30 95 s 5 Tension failure in metal a e O 0OO48 o0055 o0057 o 36-15-2 s 3 8 o 4 8 5,630 5,630 5,630 o • o o • o o 2,815 1,690 1,125 o o o o o o o 50 30 20 o o o 41,700 8 959,600 8 16,910,300 8 80 8 20 Tension failure in metal 60 s 40 o> 0) o0050 o0053 0OO46 —Tests were made in an axial-loading fatigue machine at a rate of 900 cy- cles per minute o Tension loading produced shear stresses in single-lap specimens o The 1 -inch -wide specimens were made from o 064-inch 24S-T3 clad aluminum alloy with a 3/8-inch lap. —Control -strength values are the average shear strength at -65* to -70 s Fo for 2 test specimens cut from the same panel as the fatigue-test speci- mens o The control specimens were the 2 outside specimens and the fatigue specimens the 3 center specimens in a group of 5 specimens o ^Minimum repeated stress for each cycle of loading was 10 percent of the maximum for that cycle o Report No. I836 Table 15 » -- Summary of individual results of fatigue tests at room temperature of lap-joint specimens bonded with adhesive 37— Specimen: Control, No. : strength-'. 37-10-2 3 4 37-11-7 8 9 37-12-2 3 4 37-13-7 8 9 P.S.I . 3,760 ,'60 3,760 3,530 3,530 3,530 3,500 3,500 3,500 3,460 3,460 3,460 37-14-2 : 3,590 3 s 3,590 e 4 : 3,590 5-7 : 3,235 8 s 3,235 9 I 3,235 Maximum re- : peated stress*^: P.s.i. .Percent; • 9l : .control: 2,630 ! 1,880 ! 770 i 70 : : 50 : . 20.5 : 2,470 ! 1,765 . 705 ! . 70 : 50 : . 20 : 2,100 : 1,050 : 875 i 60 :* 30 : 25 1 2,075 ! 1,040 ; 865 ! l 60 30 : 25 s 1,435 i 900 ! • . 40 : . 25 : Cycles to :Cohesion:Adhesion:Adhesive- failure : failure : failure i film : . thickness Percent s Percent ; Inch * 5 23,400 6,244,700 ^ 5 55,200 22,353,400 100 993,600 1,859,500 A 5 1,048,900 2,365,300 205,300 : 21,677,200 720 : 20 : 22,139,300 o c • • 1,295 : 40 : 481,100 810 s 25 : 24,516,400 810 : 25 : 15,325,000 90 : 90 : 90 s e 85 s 85 : 70 : 75 : 80 : 90 : 80 : 85 s 90 : 65 % Specimen fail >••«#•• QO 1 c 35 i Specimen fail 70 : 10 : 10 : 10 : © 15 8 15 I 30 : e 25 : 20 : 10 : 20 : 15 i 10 : e 35 did nots 15 : did not 30 : 0,0057 .0059 .0062 .0061 .0061 .0057 .0068 .0065 .0065 .0053 .0054 .0050 .0058 .0065 061 .0056 .0056 ,0058 —Tests were made in an axial -loading fatigue machine at a rate of 900 cycles per minute. Tension loading produced shear stresses in single-lap spec mens. The 1-mch-wide specimens were made from 0. 064-inch 243-T3 clad aluminum alloy with a 3/8-inch lap. -Control-strength values are the average shear strength at 72° to 76* F. for 2 test specimens cut from the same panel as the fatigue-test specimens. The control specimens were the 2 outside specimens and the fatigue speci- mens the 3 center specimens in a group of 5 specimens. ^Minimum repeated stress for each cycle of loading was 10 percent of the maximum for that cycle. ^he number of cycles to failure was estimated because the specimen failed luring adjustment of fatigue machine, apparently due to accumulative creep in adhesive. Report No. I836 Table 16 » — S ummary of individua l results of fatigue tests at -65 ° t o - 7 0* F* of lap-jo int specimens bon ded with adh esive 37- Specimens Control : I^feocimum re- ? Cycles to s Cohesion : Adhesions Adhesive - Noo sstrength-s peated stress^-; failure ^failure s failure ! film is % 8 8 2 thickness i.._ M * _ - . . Xv Solu P*s»i s Percent i Percent s Percent Inch o « © • • o • • Of ! ontrol s • • • • • • • 37-10-7 * 5,470 3,830 * 70 • o 17,200 g 85 s 15 g 0=0052 8 • 5,470 o 2,190 i 40 © 153,900 © 60 8 40 o0056 9 o 5,470 O 1,530 ! 28 o 773,500 8 20 g 80 % o0074 37-11-2 c 5,310 o e 3,720 o • 70 © o 36*600 a 80 1 20 • .0062 3 o ■ 5,310 © 2*120 o * 40 c « 368*000 c 70 s 30 © o0059 4 o o 5,310 g 1,485 o 28 o 1,498*100 • Tension failure a ,0074 c o • • o e in metal © o o o c © • 37-12-7 5,470 o e 3,280 60 o 21*300 90 8 10 % 0OO66 8 o o 5,470 c • 1,640 g 30 o 2*012*000 Tension failure 0OO58 e o o o • in metal 9 o © 5,470 c 1,365 25 © 4*420*000 > QO 0000000 .0074 37-13-2 o • 5,190 o 3,115 o • 60 • o o 58*800 © 75 25 © o0057 3 e • 5,190 s 1,560 • 30 o o 8,137,400 Tension failure ■ o0059 o $ o • * in metal 4 o o 5,190 o e 1,140 © 22 21,240*300 Specimen did not 8 o0052 s e © o o © fail g o o © e o • a O • 37-14-7 • 5,320 o 2,660 o o 50 o o 67,200 75 s 25 t o0057 8 o 5,320 o 1*860 35 361*900 65 s 35 o0055 9 5,320 1,330 • 25 o 4*747,800 g Tension failure S o0051 • o o e e in metal O O o • o o a 8 37-15-2 o • 5,420 2,710 s 50 o 129,500 c 65 s 35 O a o0059 3 5,420 o o 1,895 o o 35 o e 1*420*000 90 8 10 .0063 4 o 5,420 o a 1,190 s 22 © 6*113*000 * Tension failure s 0OO52 • • o o • in metal -Tests were made in an axial -loading fatigue machine at a rate of 900 cy- cles per minute^ Tension loading produced shear stresses in single-lap specimens c The 1 -inch-wi.de specimens were made from o 064-inch 24S-T3 clad aluminum alloy with a 3/8-inch lap D 2 -Control-strength values are the average shear strength at -65 * to -70 s Fo for 2 test specimens cut from the same panel as the fatigue-test speci- men So The control specimens were the 2 outside specimens and the fatigue specimens the 3 center specimens in a group of 5 specimens e ^Minimum repeated stress for each cycle of loading was 10 percent of the maximum for that cycle o Report Noo 1836 Table 17. — Summary of individual results of fatigue tests at room tem- perature of lap-joint specimens bonded v;ith adhesive 38! Specimen No Control strength— P.s.i. Maximum re- peated stress i: Cycles to failure PcSol* ^ Percent ; i controls Cohesion i Adhesion -Adhesive- failure j failure : film : ithickness Percent s Percent RUN 1 Inch 38-10-2 : 3 : 4 : 2,680 2,680 2,680 ! 1*875 : 1,070 : 535 • • • 70 40 20 o • • 300 14,700 31,164,200 • i 25 8 10 I Specimen fail 75 90 did not • ■ 0-0080 0075 .0082 38-12-2 i 3 : 4 : 2,570 2,570 2,570 : 1,540 : 1,030 : 900 o • o i © • 60 40 35 • • • 100 381,200 676,300 • c c • 80 70 50 • 20 30 50 • 0078 0095 0100 38-13-7 : 8 : 9 ! 2,950 2*950 2,950 i 1,770 : 885 i 760 • e • o • 60 30 28 • • • • • • 5 12,068,500 21,478,400 O e 60 s 40 s Specimen fail 40 60 did not • • / 1 • 0063 0078 0074 38-14-2 : 3 ! 4 : 2,720 2,720 2,720 : 1,360 815 : 825 « • • 50 30 28 • • • 4,700 19,653,800 9,028,700 c 20 90 60 e 80 10 40 • 0055 .0082 0075 38-15-7 j 8 s 9 : 2,660 2,660 2,660 ! 1,330 : 530 : 930 • c e 50 20 35 o e ■ • • 1,400 21,232,600 4,456,300 I ■ • • • • 35 Specimen fail 85 : 65 did not 15 • OO76 c0068 .0081 RUN 2 38-2-10-2 3 4 38-2-11-7 8 9 2,755 2,755 2,755 2,545 2,545 2,545 1,930 1,100 965 1,780 1,020 890 70 40 35 70 40 35 64,000 2,234,200 4,762,400 18,000 2,151,500 8,378,600 80 60 75 20 40 25 70 S 30 : 85 s 15 Specimen did not: fail 0098 .0101 .0101 0098 ,0096 0100 (Sheet 1 of 2) Report No. 1836 Table 17 «> - -Summary of individual results o f fatigue tests at room tem- perature of lap-joint specimens bonded wi th a dhesive 3&k Continued , ?! Specimen g Control Noo g strength- c r » S e 1 38-2-12-2 s 2,565 3s 2,565 4s 2,565 38_2-13-7: 2,535 8s 2,535 Maximum re- _g peated stressor PoSoio g Percent s g of : s control : 1,540 770 1,155 1,520 760 9s 2,535 : 1,140 60 30 45 60 30 45 Cycles to gCohesiongAdhesiongAdhesive- failure s failure s failure g film s g gthickness g Percent g Percent s Inch 193,800 s 60 g 40 s o0097 17,079,800 : Specimen did notg o 0091 s fail g 168,600 g 60 g 4O g o0090 000 000 339*000 g 85 g 15 s ,0105 14,824,500 g Specimen did nots 0OIO4 g fail g 724,200 % Tension failure g 0OIO6 g in metal g 38-2-14-2 s 2,890 o o 3g 2,890 38-2-15-7* 8g 2,790 2,790 1,445 1,010 1,395 975 50 35 50 35 438,800 1,679,800 183,500 447,900 Tension failure in metal 80 g 20 60 60 40 40 o0105 oOlOl o0094 ,0087 ~Tests were made in an axial -loading fatigue machine at the rate of 900 cy- cles per minute « Tension loading produced shear stresses in the single- lap specimens « The 1 -inch-wide specimens were made from u 064~inch 24S-T3 clad aluminum alloy with a 3/8-inch lap^ -Control-strength values are the average shear strength at 72® to 76" Fo for 2 test specimens cut from the same panel as the fatigue-test specimenso The control specimens were the 2 outside specimens and the fatigue speci- mens the 3 center specimens in a group of 5 specimens. ^Minimum repeated stress for each cycle of loading was 10 percent of the maximum for that cycle o (Sheet 2 of 2) Report No e I836 Table 18. — Summary of individual results of fatigue t e [ - -65" to -70* F of lap-.iomt specimens bonded with adhesive 3 8 ( run 2)- Specimen No. 38-2-10-7 8 38-2-11-2 3 38-2-12-7 8 38-2-13-2 3 U 38-2-14-7 38-2-15-2 3 Control strength- k ■ s r. 3,820 3,820 3,820 3,640 3,640 "aximum re- '. Cycles to i Cohesions Adhesion i Adhesive - peated stress^-: failure : failure .failure : film : i :tnickness P. s.i. ; Percent : ; of : •control; 2,675 1,530 70 40 1,335 : 35 2,550 1,455 3,660 : 2,195 3,660 s 1,100 3,660 3,890 3,890 3,890 3.640 3,670 3,670 2,930 2,335 1,165 3,110 1,820 1,835 1,470 70 40 60 30 80 60 30 80 50 50 40 12,300 5,033,000 11,615,400 13,500 21,879,100 125,800 20,372,300 4,600 158,400 20,097,700 5,000 505,700 : Percent .Percent 100 s : Tension failure : in metal : CIO \ < 100 : Specimen did not : fail o I 100 1 Specimen did not; fail 100 s ! o 1 o 4 Tension failure : in metal Specimen did not: fail 100 s o i o 4 Tension failure i in metal : 332,200 s . QO •. ■ jfcuu o c c • o o «UU «» a o • o • c • j ,<4-l 7 , fcUU CIO Inch 0097 .0097 0092 .0099 0100 0091 0089 0088 0108 0103 0105 0097 0087 .0087 —Tests were made in an axial-loading fatigue machine at the rate of 900 cy- cles per minute. Tension loading produced shear stresses in the single - lap specimens, The 1-inch-wide specimens were made from 0,-064 -inch 24S-T3 clad aluminum alloy with a 3/8-inch lap. 2 -Control -strength values are the average shear strength at -65° to -70* Fo for 2 test specimens cut from the same panel as the fatigue -test speci- mens. The control specimens were the 2 outside specimens and the fatigue specimens the 3 center specimens in a group of 5 specimens ^Minimum repeated stress for each cycle of loading was 10 percent of the maximum for that cycle. Report No, 1836 Table 19 • —Summar y of indivi dual r esults of fatigue tests at room temperature of lap -.joint specimens bonded with adhesive_41=- Specimen 86 o Control Maximum re~ s strength— o peated stresses o foSols PoSoio g Per cent: of : controls Cycles to gCohesion?Adhesion 'Adhesive - failure g failure ;; failure s film g g gthickness : Percent ^Percent : Inch 2,1-10-2 3 4 o o o o o 3,950 3,950 3,950 o 9 2,765 s 1,580 g 1,185 s o o 70 40 30 o o o © o o 300 8 53,200 g 22,000,500 8 o> 90 8 95 1 Specimen fail 10 g 5 t did notg U 0090 0090 o0090 41-11-7 8 9 • o o 4,540 4,540 4,540 m o o 3,180 g 1,815 s 1,590 s 70 40 35 o> o o a o -200 g 17,800 s 120,300 8 95 95 95 5 5 5 • o005? 0OO58 ,0066 41-12-2 3 4 o o o o * 4,340 4,340 4,340 o o o o o 2,005 g 1,300 g o 1,520 g 60 30 35 o o o • 2,600 8 20,906,700 g 276,500 8 100 8 Specimen fail 90 8 8 did nots 10 g 0OO64 .0057 »0060 41-13-7 8 9 c o o o 4,980 4,980 4,980 ' 2,990 g 1,495 : 1,495 i 60 30 30 o o 100 8 146 J 000 s 73,000 g 95 100 95 * 5 5 0OO45 0OO58 0OO63 41-14-2 3 4 o c o • 4,260 4,260 4,260 o • 2,130 g 850 g 1,065 g 50 20 25 • « » 5,800 g 18,413,900 8 ' ** o> • 20,862,200 8, 100 8 Specimen fail 00000 o&O g did nots OOOOOOOo c0O75 O 0057 O 0059 41-15-7 8 9 • o o o • 3,830 3,830 3,830 o o o 1,915 i 1,150 s 960 s o 50 30 25 o o « 16,100 8 -560,000 g 20,817,700 8 100 100 8 Specimen fail g 8 did notg 0OO86 0096 .0093 =Fests were made in an axial -loading fatigue machine at a rate of 900 cycles per minute o Tension loading produced shear stresses in single-lap specimens < The 1 -inch-wide specimens were made from 064-inch 24S-T3 clad aluminum alloy with a 3/8-inch lap, 2 —Control -strength values are the average shear strength at 72 m to 76 3 Fo for 2 test specimens cut from the same panel as the fatigue-test specimens The control specimens were the 2 outside specimens and the fatigue specimens the 3 center specimens in a group of 5 specimens ^Minimum repeated stress for each cycle of loading was 10 percent of the maximum for that cycle o Report Noo 1836 Table 20 . - - Summary of individual results of fatigue tests at -65* t o of lap-^oint specime ns bonded with adhesive 4ll Specimen "ontrol : Maximum re- J Cycles to g 1 Cohesion: Adhesion Adhesive- ;:o sstrengtb^. ■ • • peated otres A failure i failure .failure e • ?PerceriT ; Per cent • • C • • film hickness I 1 :P ercent : Inch • • i ; control: • • • e • • 41-10-7 8 9 • 3,000 .000 3,000 • • • • • • 2,100 : 1,200 s 1,500 ; 70 40 50 12,800 19,728,300 754,600 • 50 50 Specimen did not . fail 60 s 40 0064 ,0056 .OO48 41-11-2 3 • • • • 3,130 3,130 • s • 2,190 : 1,250 : 70 40 2,600 8,569,000 • • 70 g 30 Tension failure in metal • 0037 0044 41-12-7 8 9 • • • 2,860 2,860 2,860 • • • • • 1,715 ! 860 1 1,145 : • 60 30 40 • • e • 22,300 17,142,400 4,981,400 • ■ 40 s 60 90 s 10 Tension failure in metal « 0081 0083 .0072 41-13-2 k • ■ • 2,940 2,940 • c c e 1,765 ! 2,060 ? 60 70 » • 40,600 7,900 • • 70 s 30 80 20 • • 0063 0062 41-14-7 8 9 • e 2,950 2,950 2,950 • • • • 1,475 ! 1,325 : 2,360 t 50 45 80 • • • 285,700 3,440,800 2,900 * • ■ 90 : 10 Tension failure in metal 80 t 20 • O O • 0043 0039 0043 U 5-2 3 4 * O • • • e 2,820 2,820 2,820 • • • « • • 1,410 2 1,270 : 2,255 s 50 45 80 • • • • 2,769,600 2,110,500 1,500 1 Tension failure in me+al 25 75 85 : 15 O I • • • 0064 0060 0096 -Tests were made in an axial -loading fatigue machine at a rate of 900 cycles per minute. Tension loading produced shear stresses in single-lap speci- mens. The 1 -inch-wide specimens were made from 0.064-inch 243 -T3 clad aluminum alloy with a 3/8- inch lap.- 2 -Control -strength values are the average shear strength at -65* to -70* F for 2 test specimens cut from the same panel as the fatigue-test specimens The control specimens were the 2 outside specimens and the fatigue speci - mens the 3 center specimens in a group of 5 specimens •^Minimum repeated stress for each cycle of loading was 10 percent of the maxi- mum for that cycle. Report No. 1836 Table 21. — Teat data obtained In long-time-loading teats of 1/2-lnch lap-Joint specimens of 0.064-lnch 24S-T3 clad alumlnura alloy bonded with adhesive 25- Specimen No. 25-7-3 25-4-4 25-6-4 25-2-4 25-5-3 25-8-4 25-9-4 25-1-3 25-7-4 ?5-7-9 25-6-9 25-5-4 25-3-9 25-3-4 25-9-3 25-8-9 25-1-9 25-5-9 25-1-4 25-2-9 25-9-9 25-7-7 25-8-3 2 5-6-3 25-4-2 25-6-2 25-9-6 25-8-6 25-4-3 25-6-6 25-7-2 25-9-2 25-3-6 25-5-6 25-5-2 25-2-6 25-7-5 25-2-2 25-2-3 25-8-2 25-9-7 25-1-2 25-3-2 Duration of stress Hours 0.02 .10 .22 .44 .50 1.13 2.25 4.33 4.36 5.63 6.72 13.75 20.33 23.37 24.20 34.80 45.72 77.53 More than 200.00 " 200.00 ■ 200.00 0.03 0.08 0.23 0.80 1.03 1.63 2.70 3.17 3.72 4.15 5.39 8.25 10.92 12.00 14.33 14.65 20.75 41.65 More than 200.00 " 200.00 » 200.00 ■ 200.00 Constant stress P.e.l. Percentage of control strength^ Type of failure Adhesion: Cohesion to metal: Peroent :Peroent Under test at 72° to 76° F . Film thloknese : 2,800 83.7 5 : 95 : : 2,500 80.1 25 . 75 : : 2,400 70.8 10 90 : : 2,400 74.3 100 : : 2,300 71.6 20 : 80 : : 2,200 65.2 5 95 : : 2,300 67.8 : 100 : : 2,150 70.2 5 95 : : 2,050 61.3 5 95 : : 2,100 62.8 5 95 : : 2 , 200 64.9 5 95 : : 1,950 60.7 25 75 : : 2,050 68.4 20 80 : : 2,000 66.7 70 • 30 : : 2,150 63.4 100 : : 2,000 59.3 5 95 : : 2,000 65.3 10 90 : : 1,950 60.7 5 95 : : 1,950 63.6 Not broken : : 1,950 60.4 « • : 1,900 56.0 " ! Un< \er test at 17< 1° to 182° F. : 1,600 47.8 : 100 : : 1,600 47.4 5 95 : : 1,600 47.1 5 95 : : 1,500 48.1 10 90 : : 1,550 45.7 5 95 : : 1,400 41.2 5 95 : : 1,200 35.5 5 95 : : 1,300 41.6 10 90 : : 1,100 32.4 25 75 : : 1,300 38.3 25 75 : : 1,400 41.2 100 : : 1,050 35.0 35 65 : : 1,000 31.1 40 i 60 : : 1,100 34.2 50 50 : : 1,050 32.5 15 85 : : 1,050 31.3 20 80 : : 1,200 37.1 30 70 : : 1,100 34.0 20 80 : : 1,000 29.6 40 60 : : 950 28.0 40 60 : : 950 31.0 Not broken : 800 26.7 > n Inch 0.0075 .0088 .0088 .0082 .0092 .0080 .0066 .0073 .0089 .0081 .0094 .0099 .0082 .0087 .0068 .0082 .0073 .0095 .0069 .0080 .0076 .0049 .0085 .0089 .0083 .0093 .0070 .0086 .0087 .0090 .0089 .0071 .0084 .0091 .0090 .0088 .0088 .0087 .0075 .0090 .0055 .0075 .0083 Creep measurement^ After : After loading loadlng:and conditioning Inoh I nob. 0.0150 .0202 .0166! 0.0066 .0105 .0078 .0200 .0164 .0182 .0154 iThe control strength was the average strength, at 72° to 76° F. and at a loading rate of 300 rounds per minute, of 3 specimens selected from the same bonded panel as the test specimen. -The creep was measured by observing with a measuring microscope the offset of a fine line scribed across the edge of the bonded Joint. Measurements were taken of the amount of creep after 200 hours of loading. These measurements were made both while the specimen was under load and following i wee k of room-temoerature conditioning after the load was removed. ZM 86590 F Table 22.-- Teat data obtained In long-time-loading teste of 1/2-lnch lap-joint specimens of 0. 063-Inch 24S-T3 clad aluminum alloy bonded with adhealves 26 and 25 Specimen No. Duration of stress Constant stress Percentage of control etrengthi Type of failure Adhesion: Cohesion to metal : Film thickness Creep measurement^ After :After load- loading : lng and : conditioning Hours P. 8.1. Percent: Percent Inch Inch : Inch : : 26-6-4 26-7-7 26-VA 26-3-3 26-5-3 26-8-4 26-1-9 26-2-4 26-3-9 26-9-4 26-5-9 26-9-7 26-7-9 26-6-9 26-7-4 26-5-4 26-7-3 26-2-9 26-4-9 26-9-9 26-9-3 26-1-3 26-4-4 ?6-6-6 26-4-3 26-1-2 26-8-6 26-6-3 26-4-6 26-9-2 261-3-6 26-6-2 26-2-2 26-9-6 26-5-6 26-8-3 26-8-2 26-1-6 26-3-2 26-2-6 26-2-3 26-5-2 26-4-2 26-7-2 26-7-6 Under test at 72° to 76° F. 0.03 .18 .45 .82 1.48 6.87 8.48 10.48 11.80 14.00 14.17 15.67 24.70 33.30 53.68 58.12 65.98 136.92 171.42 198.00 Uore than 200.00 ■ 200.00 ■ 200.00 : 0.22 : .57 : .68 : .75 : 1.27 : 1.57 : 1.65 : 3.60 : 3.75 : 7.62 J 9.73 : 12.92 : 16.83 : 27.40 : 28.05 : 30.00 : 71.23 : 118.21 j 178.28 JMore than 200.00 I ■ 200.00 : ■ 200.00 : 2,500 2,450 2,500 2,500 2,475 2,350 2,400 2,450 2,350 2,400 2,450 2,250 2,450 2,400 2,250 2,300 2,300 2,200 2,175 2,200 2,200 2,150 2,150 , 76.2 73.8 74.2 74.2 71.5 70.3 70.9 69.9 69.7 71.2 70.8 66.7 73.8 73.2 67.7 66.4 69.2 62.8 64.2 65.3 65.3 63.5 63.5 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 Under test at 178° to 182* F. 1,600 : 1,550 : l,6oo : 1,500 j 1,300 1,450 1,550 l,4oo 1,450 1,350 1,400 1,400 1,300 1,300 1,250 1,200 1,200 1,200 1,300 1,150 1,150 1,000 48.8 45.7 47.2 44.8 39.6 42.7 45.9 41.5 44.2 38.5 41.5 40.1 38.8 38.8 36.8 35.6 34.2 34.2 37.5 33.9 34.6 30.0 5 5 5 5 5 5 10 20 15 25 20 15 35 20 100 100 100 100 100 100 100 95 95 95 100 95 95 95 90 80 85 75 80 85 65 80 0.0056 .0058 .0052 .0054 .0051 .0044 .0044 .0046 .0051 .0062 .0045 • 0053 .0046 .0051 .0048 .0045 .0052 .0047 .0054 .0058 .0053 .0043 .0063 .0053 .0056 .0048 .0051 .0050 .0053 .0060 .0055 .0046 .0046 .0051 .0044 .0047 .0044 .0049 .0051 .0050 .0046 .0047 .0048 .0052 .0043 I — 0.0129 .0123 .0126 0.0070 .0062 .0150 : — .0142 : .0163 : .0148 ^The control strength was the average strength, at 72° to 76° F. and at a loading rate of 300 pounds per minute, of 3 specimens selected from the same bonded panel as the test specimen. -The oretp was measured by observing with a measuring microscope the offset of a fine line scribed across the edge of the bonded Joint. Measurements were taken of the amount of oreep after 200 hours of loading. These measurements were made both while the specimen was under load and following l week of room- temperature eondltlonlng after load was removed. 2 K 87126 r Table 25. -- Test data obtained in long- time- loading tests of l/2-inch lap-joint specimens of 0.06U- inch 21+S-T3 clad aluminum alloy bonded with adhesive 33 - Specimen No. Duration of stress Constant stress Percentage of control ? strength- Type of failure Film thickness 3 Creep measurement* Adhesion: Cohesion to metal: After loading After loading and conditioning Hours P.s.i. Per c ent : Perc ent Inch Inch Inch 33-9-1+ 0.1+5 3,750 33- 3- ^ .50 3,800 33- 6- U .85 3,725 33- 5-^ More than 200.00 3,800 33-7-^ . . . .do. . . . 200.00 3,700 33-T-3 . . . .do. . . . 200.00 3,600 33-^-2 1.10 1,800 33-^-3 6.05 1,750 33 -h- 6 9.07 2,000 33-2-3 9.17 1,900 33-2-6 11.1+8 1,650 33-3-2 21.88 1,700 33-6-6 52.12 1,800 33-5-2 91.^5 ' 1,650 33-1-2 115.75 1,750 33-8-3 • More than 200.00 • 1,600 33-8-2 • ....do. .. . 200.00 : 1,600 : 20 80 : : 1+0 60 : : 1+0 60 : : Not broken : Under test at 72° to 76° F. 8l.lt 85.2 80.1* 83. k 79.6 77. ^ Under test at 178" to 182° F. 38.1 37.1 1+2.1+ 1+0.3 3^.9 38.O 38.8 36.2 38.1+ 38.6 38.6 : 35 65 : : 35 65 : : 1+0 60 : : 30 70 : : 20 80 : : 35 65 : : 30 70 : : U5 55 : : 1+0 60 : : Not broken : 0.0037 .0022 .0032 . .0033 0.0000 : 0.0000 .0029 • .0000 : .0000 .0035 -.0000 : .0000 .0029 .0029 : . . .0031 : . . .0032 :.. .0028 ...,...,:.. .0029 .. .■*...».. .0031+ : . . .0033 ........:.. .0026 '.«. •....:.. .0033 .0072 : .0062 .0035 .0090 : .0086 -Test data for comparison with the more comprehensive test data (table 25) obtained for adhesive 35. 2 -The control strength was the average strength, at 72° to 76° ~F. and at a loading rate of 300 pounds per minute, of 3 specimens selected from the same bonded panel as the test specimen. -The creep was measured by observing with a measuring microscope the offset of a fine line scribed across the edge of the bonded joint. Measurements were taken of the amount of creep after 200 hours of loading. These measurements were made both while the specimen was under load and following 1 week of room- temperature conditioning after the load was removed. ZM 89836 F Table 24 . — Testdata obtained In long-time-loading tests of 1/2- Inch lap- Joint 0. 064-Inch 243- T3 cltd aliralnun alloy bonded with adhesive "5% specimens of Specimen Wo. 34-6-9 34-4_4 34-7-4 34_->_4 34-3-4 34-1-0 34-7-^ 54-3-3 34-1-9 34-8-4 34-9-3 34-1-4 34-5-4 34-7-9 34-5-9 34-2-9 34-4-9 34-9-4 34-9-9 34-8-9 34-4-3 34-3-6 34-2-3 34-8-6 34-8-2 34-2-6 34-9-2 34-6-2 34-2-2 34-7-7 34-8-7 34-6-3 34-7-2 34*- 8-3 14-7-6 34-4-2 34-3-2 Duration of stress Houre 0.40 .67 .68 4.22 .34 12.50 16.11 20.13 31.63 38.67 57.93 58.58 85.53 176.33 185.97 More than 200.00 " 200.00 " 200.00 " 200.00 " 200.00 " 200.00 .13 .15 .38 .61 1.00 1.40 1.53 2.58 2.63 2.67 2.92 than 200.00 " 200.00 " 200.00 " 200.00 " 200 . 00 " 200.00 Constant Btrene P.8.1. Percentage of control strength! Type of failure Adhesion: Cohesion to metal: Percent : Percent Film thickness Under test at 72° to 76° F. 3,560 3,530 3,524 3,500 1,440 3,420 3,484 3,350 3,350 3,440 3,420 3,500 3,484 3,484 3,304 3,524 3,400 3,400 3,320 3,316 3,264 1,000 950 875 800 800 780 750 740 705 740 730 730 725 705 700 650 580 Inch 0.0039 .0034 .0038 .0037 .0020 .0050 .0041 .0038 .0053 .0029 • 0035 .0031 .0032 .0036 .0042 .0031 .0027 .0044 .0032 .0038 .0026 .0034 .0048 .0030 .0034 .0035 .0026 .0033 .0042 .0025 .0043 .0037 .0047 .0037 .0030 .0040 .0035 .0042 Creep measurement?. After loading Inch After loading and conditioning inch . 0000 .0005 .0005 .0014 .00C4 .0000 0.0000 .0005 .0009 .0014 .0004 .0000 .0041 .0014 .0074 .0007 .0038 .0027 .0040 .0014 .0067 .0007 .0038 .0026 i.The control strength was the average strength, at 72° to 76° ?. and at a loading rate of 300 -Dounds oer minute, of 3 specimens selected from the same bonded nanel as the test specimen. —The cre»o was measured by observing with a measuring microscope the offset of a fine line sorlbed across the edge of the bonded Joint. Measurements -'ere taken of the amount of creep after 200 hours of loading. These measurements were made both while the specimen ws under load and following 1 week of room-temneriture conditioning after the load woq removed. Z M 85232 F Table ?5. — Teat data obtained In lo 24-S-T3 clad aluminum onfi z tlme-loa<11nR teats of l/?-lnch lan-.lolnt specimens o f 0.064_ ln ch alloy bonded -vlth adhesive ^5. ~ — Speclmen No. Duration of stress Hours Constant stress P. s.l. Percentage of control strength! Type of failure Adhesion: Cohesion to metal: Percent :Percent Film thickness Inch Creep measurements- After : After loading loadlng:and conditioning Inch Inch Under test at 72° to 76° F. 35-6-4 0.03 3,900 100.7 30 : 70 0.0026 ___ 35-9-9 .03 3,850 97.5 10 90 .0028 35-5-3 .03 3,800 100.9 5 95 .0031 — 35-7-4 .06 3,800 98.0 35 65 .0035 35-7-9 .20 3,775 94.8 5 95 .0030 _— -— 35-3-9 .97 3,800 102.5 10 90 .0030 — 35-6-9 1.16 3,750 96.7 5 95 .0028 — - 35-7-3 5.53 6.47 3,775 94.8 25 75 .0036 35-8-9 3,775 96.5 : 5 95 .0030 — — 35-1-3 7.45 3,700 87.1 : 5 95 .0028 35-9-4 8.60 3,750 95.0 5 95 .0029 35-3-4 173.35 3,675 99.1 20 80 .0031 35-8-4 More than 200.00 3,750 95.9 Not broken .0037 0.0005 0.0004 35-1-9 ■ 200.00 3,700 87.1 n .0029 .0004 .0004 35-1-4 " 200.00 3,650 85.9 15 : 85 .0025 .0019 Broke at 225 hours 35-9-3 ■ 200.00 3,500 88.6 Not broken .0030 .0000 .0000 35-4-9 " 200 . 00 3,200 84.0 • " .0030 .0000 .0000 Under test at 178° to 182° F. 35-3-6 .15 2,000 53.9 : 100 .0031 __ . ___ 35-1-6 .26 1,700 4o.O 5 95 .0032 35-8-7 .45 2,000 51.2 100 .0035 35-2-6 .92 2,000 52.0 100 .0028 ___ _— 35-5-6 1.12 1,750 46.5 100 .0031 ___ 35-8-2 1.28 1,800 46.0 100 .0034 35-3-2 1.70 2,000 53-9 100 .0028 35-1-2 2.80 1,750 41.2 5 95 .0032 ___ 35-2-3 2.82 1,900 49.4 5 95 .0030 - — 35-6-2 2.93 1,800 46.4 100 .0028 35-4-2 3.35 1,950 51.2 100 .0027 35-2-2 3.65 2,000 52.0 5 95 .0029 35-9-6 4.42 1,900 48.1 100 .0029 35-8-3 7.07 1,650 42.2 100 .0031 35-5-2 7.20 1,800 47.8 100 .0030 35-4-6 8.53 1,600 42.0 100 .0034 35-9-2 10.26 1,700 43.0 100 .0033 _ — ___ 35-6-3 10.78 1,750 45.1 100 .0028 35-6-6 42.75 1,600 41.2 100 .0030 35-7-2 More than 200.00 1,700 42.7 Not broken .0041 .0075 .0075 35-7-7 " 200.00 1,550 38.9 H .0030 .0049 .0048 35-4-3 " 200.00 1,500 39.4 II .0030 .0067 .0067 35-7-6 " 200.00 1,500 37.6 II .0035 .0018 .0018 35-8-6 " 200 . 00 1,000 25.6 II .0034 .0060 .0059 ^The control strength was the average strength, at 72° to 76° F. and at a loading rate of 300 sounds per minute, of 3 soeclmens selected from the same bonded Danel as the test specimen. —The creep was measured by observing with a measuring microscope the offset of a fine line scribed across the edge of the bonded Joint. Measurements were taken of the amount of oreep after 200 hours of loading. These measurements were made both while the specimen was under load and following 1 week of room-temperature conditioning after the load was removed. 2M 86591 F Table 26. Test data obtained In lonft-tlme-loadlng teats of 1/2-lnch lap-Joint specimen 0.064-lncn 248- T3 clad alu.-3lr.um alloy bonded '.Tlth "adhesive 36. a of Specimen No. 16-3-9 36-9-9 . J 36-4-* 36-1-9 36-1-4 36-7-9 36-3-4 36-7-3 36-5-3 36-8-9 36-5-9 36-6-4 36-1-3 36-9-3 36-7-4 36-1-9 36-9-4 36-5-4 36-8-4 36-3-2 36-4-6 36-2-6 36-2-3 36-8-6 36-6-6 36-7-6 36-1-6 36-9-2 36-4-2 36-6-3 36-5-2 36-3-6 36-8-3 36-7-2 36-5-6 36-6-2 36-4-3 36-1-2 36-8-2 36-2-2 36-9-6 Duration of a tree s Hours 0.07 • 33 .70 • 90 1.67 3.33 3.85 12.50 14.62 20.63 31.83 35.25 36.40 57.27 91.47 99.13 117.66 More than 200.00 ■ 200 . 00 " 200.00 10 15 26 00 12 28 1 1 1 2.73 4.22 7.63 3.42 14.22 15.80 22.25 37.73 48.33 82.07 129.72 174.40 than 200.00 1 200 . 00 1 200 . 00 ' 200 . 00 Constant Percentage of atreee : control atrengthi P. s.l. 3,000 2,800 3,000 2,600 2,500 2,430 2,800 2,500 2,350 2,700 2,400 2,200 2,300 2,200 2,200 2,150 2,150 2,150 2,100 2,100 Type of failure Adhesion: Cohesion to metal: Percent :Peroent Under test at 72° to 76» F. 87.6 81.2 87.1 81.0 70.1 68.1 79.9 73.0 67.0 76.9 69.8 62.6 68.5 61.7 63.8 61.3 60.3 62.3 59.8 61.1 Under test at 178 c 1,000 800 900 800 700 800 700 700 650 600 575 600 700 450 500 600 400 400 400 350 350 29.2 24.9 26.1 23.2 20.4 23.9 20.0 19.6 18.8 18.7 17.1 17.1 20 li 17 11 12 'I 15.4 11.6 10.2 10.1 10 : 90 10 : 90 5 : 95 5 95 10 : 90 15 85 5 95 10 : 90 5 95 5 95 10 ! 90 5 95 5 95 10 90 10 90 10 90 10 90 Not broken to 182° r. 25 75 25 75 25 75 25 75 45 55 35 65 25 75 5 95 15 85 5 95 15 85 10 90 5 95 15 85 10 90 5 95 5 95 20 80 Not bi • • ■ ~oken Film thickness Inch 0.0036 .0038 .0040 .0049 .0036 .0047 .0037 .0042 .0045 .0044 .0040 .0042 .0044 .0042 • 0035 .0046 .0036 .0041 .0038 .0037 .0042 .0045 .0037 .0037 .0035 .0042 .0048 .0037 .0048 .0045 .0037 .004o .0045 .0039 .0042 .0047 .0041 .OO50 .0047 .0041 .0042 .0035 Creep measurement?. After : After loading loadlng:and conditioning Inch : Inch 0.0184 .0220 .0220 0.0110 .0119 .0105 .0183 .0188 .0293 .0140 .0128 .0098 .0112 .0126 ^The oontrol strength was the aTerage strength, at 72° to 76° F. and at a loading rate of 300 pounds per minute, of 3 specimens selected from the same bonded panel as the test specimen. -The creep was measured by observing with a measuring microscope the offset of a fine line scribed across the edge of the bonded Joint. Measurements were taken of the amount of oreep after 200 hours of loading. These measurements were made both while the epeolaen was under load and following 1 week of room-temperature conditioning after the load was removed. Z M 85790 7 Table 27. — Test data obtained In long-time-loading testa of 1/2-lnch lap-.lolnt specimens of .064-Inch 2 43-T3 clad aluminum alloy bonded with adhesive 37. Specimen Duration Constant Percentage of Type of failure Film Creep measurement^ No. of stress stress oontrol strength! Adhesion: Cohesion to metal: thlokness After : After loading loading: and conditioning _ — — ■■ . ■«. — — —— Hours P.s.l. Percent : Percent Inoh Inch : Inch Under test at 72° to 76° F . 37-2-4 : 0.60 2,800 : 75.9 : 5 : 95 : 0.0051 37-3-4 : .73 2,800 76.4 : 5 95 : . 0065 37-1-9 : 1.83 2,600 : 70.4 5 95 : .0064 37-3-3 : 2.63 . 2,670 : 72.9 5 95 . .0076 37-2-9 : 5.92 2,700 : 73.9 5 95 .0052 37-4-4 : 8.07 2,500 66.0 5 95 .0043 37-9-3 37-1-4 ! 8.52 2,300 66.8 5 95 .0047 ! 14.28 2,400 65.1 10 90 .0051 37-4-9 : 15.26 2,500 66.0 5 95 .0043 37-7-3 ! 17.12 2,100 ! 60.9 5 95 .0052 37-8-4 : 19.48 2,150 61.9 5 95 .0059 37-5-4 : 25.72 2,000 60.6 5 95 .0054 37-6-9 : 27.22 2,200 62.4 5 95 .0062 37-8-9 : 36.75 2,000 57.5 5 95 .0060 37-9-4 : 44.33 2,100 61.1 10 90 .0057 37-3-9 : 96.82 2,050 55.9 54.2 10 90 .0055 37-1-3 • More than 200.00 2,000 10 90 .0067 Unc ler test at 17< 5° to 182° F. 37-8-3 .32 1,000 28.8 40 : 60 .0059 37-3-6 .60 1,000 27.3 25 75 .0055 37-5-2 .92 800 24.2 40 60 .0043 37-9-2 1.12 900 26.2 25 75 .0049 37-6-6 1.72 900 25-5 25 75 .0043 37-4-6 6.00 700 18.5 40 60 .0052 37-1-6 6.72 750 20.3 10 90 .0045 37-2-3 7.42 800 21.9 15 85 .0062 37-6-3 7.97 800 22.7 10 90 .0057 37-7-2 9.75 500 14.5 30 70 .0045 37-9-6 12.73 500 14.5 25 75 .0046 37-2-6 12.87 700 19.1 : 35 65 .0048 37-7-6 14.13 600 17.4 40 60 .0058 37-1-2 18.85 550 15.0 10 90 .0047 37-4-2 23.35 650 17.1 ! 10 90 .0038 37-8-2 31.97 550 16.0 : 15 85 .0063 37-6-2 48.30 600 17.0 : 15 85 .0064 37-3-2 79.77 : 650 17.8 ! 20 80 .0073 37-8-7 101.17 450 12.9 : 40 60 .0057 37-2-2 More than 200.00 . 500 13.6 ! Not broken .0050 37-8-6 • 200.00 ■ 400 11.5 ! K .0054 37-7-7 " 200.00 400 11.6 : ■ .0053 37-4-3 » 200.00 : 370 9.8 : n .0042 0.0173 Broke at 217 hours . .0153 .0223 .0220 .0134 0.0139 .0193 .0197 .0121 —The oontrol strength was the average strength, at 72° to 76° F. and at a loading rate of 300 pounds per minute, of 3 specimens selected from the same bonded panel as the test specimen. —The oreep was measured by observing with a measuring mlorosoope the orfset of a fine line sorlbed across the edge of the bonded Joint. Measurements were taken of the amount of creep after 200 hours of loading. These measurements were made both while the specimen was under load and following 1 week of room-temperature conditioning after the load was removed. 2' M 85791 P Table P8. — Test data obtained In lonfi-tlme-loadlng teste of l/?-lnch lap-joint specimens of 0.064—lnch ?4S-T3 clad aTuolnun alloy bonded with adhealve 38. (Run 1) Speolaen No. Duration of stress Hours Constant stress P.s.l. Percentage of oontrol . strength* Type of failure Adhesion: Cohesion to metal: Percent : Percent film thlokness I nob Creep measurement 2 - After : After loading loadlng:and conditioning Inoh Under test at 72° to 76° T. 38-4-4 0.08 2,234 95-4 : 100 0.0071 - . ____ 38-3-* .20 2,420 92.6 40 60 .0068 38-1-3 .25 2,092 82.6 20 80 .0067 _ — 38-7-3 .26 2,050 91.0 5 95 .0077 - 38-2-9 .67 2,310 88.0 25 75 .0068 — — 38-3-9 1.75 1,790 68.6 100 .0078 38-5-9 2.67 2,000 86.0 5 95 .0102 — — 38-7-9 4.75 1,700 75.4 100 .0082 — 38-5-* 5.95 1,950 83.9 20 80 .0090 — — 38-1-4 6.50 1,796 70.9 25 75 .0048 -— -— - 38-9-9 7.83 1,700 66.4 20 80 .0079 — _ — 38-4-9 11.00 1,860 79.4 15 85 .0074 — — -— - 38-1-9 15.17 1,870 73.6 25 75 .0067 — - 38-V3 15.77 1,980 75.7 20 80 .0061 — - — 38-7-4 16.22 1,656 73.5 67.4 100 .0089 — — 38-2-4 31.70 1,770 40 60 .0067 - — — 38-9-4 52.53 1,900 74.2 15 85 .0074 — - Q _4 112.26 1,900 69.3 10 90 .0065 ___ — 38-8-9 140.68 1,600 58.3 100 .0080 — 38-9-3 185.42 1,600 62.5 15 85 .0088 38-5-3 More than 200.00 1,546 66.5 Not broken .0106 0.0173 0.0159 38-6-9 " 200.00 1,540 62.1 " .0095 .0144 .0124 38-6-4 " 200.00 1,534 Un< 61.9 ler teat at 17/ ■ 3° to 182° T. .0105 .0148 .0132 38-1-6 .02 800 31.6 35 : 65 .0086 38-2-6 .02 800 30.5 50 50 .0071 — 38-6-2 .02 750 30.3 25 75 .0075 — — 33-2-2 .08 700 26.7 50 50 .0068 — 38-5-2 .12 800 34.4 25 75 .0072 — — 38-8-2 .13 700 25.5 25 75 .0076 — 38-9-2 .47 600 23.4 80 20 .0086 — 38-4-3 1.17 600 25.6 35 65 .0064 38-8-3 1.43 500 18.2 75 25 .0076 — 38-7-6 2.55 550 24.4 30 70 .0079 — 38-4-6 5.27 450 19.2 30 70 .0070 — - ■ 38-2-3 7.15 450 17.1 65 35 .0073 38-8-6 13.15 500 18.2 50 50 .0051 _— _ - — 38-9-6 41.62 400 15.6 4o 60 .0087 — . 38-9-7 : 57.70 400 15.6 35 65 .0075 — 38-3-6 116.67 400 15.3 50 50 .0069 — 38-5-6 177.98 420 18.0 15 85 .0093 38-6-6 197.92 380 15.3 35 65 .0093 — — 38-6-3 More than 200.00 380 15.3 Not broken .0086 .0175 .0173 1-2 • 200.00 350 13.8 • .0053 .0165 .0109 38-4-2 ■ 200.00 350 15.0 ■ .0063 .0178 .0137 38-8-7 ■ 200.00 350 12.8 ■ .0082 .0141 .0117 It he control strength was the average strength, at 72° to 76o F. and at a loading rate of 300 pounds per minute, of 3 sneclraens selected from the same bonded oanel as the test specimen. —The oreep was measured by observing with a measuring mlorosoope the offset of a fine line scribed across the edge of the bonded Joint. Measurements were taken of the amount of creep after 200 hours of loading. These measurements were made both while the epeolmen was under load and following 1 week of room-temper* ture oondltlonlng after the load was removed. M 85792 F Table 29. — Test data obtained in long- time- loading tests of l/2-lnch lap-joint specimens of 0.06U-inch 21+S-T3 clad aluminum alloy bonded with adhesive 38 (run 2)- Specimen No. Duration of stress Constant stress Percentage of control strength^ Type of failure Film thickness Creep measurement^ Adhesion: Cohesion to metal: After loading : After loading :and conditioning Hours P.s.i. Percent : Percent Inch Inch : Inch Under test at 72 38-2-5-9 0.06 2,500 38-2-6-9 .28 2,200 58-2-3-1+ 1.28 2,000 38-2-1-9 1.52 1,900 38-2-5-1* 3.78 2,200 38-2-1+-9 6.48 2,100 38-2-8-9 7.12 2,000 38-2-3-9 16.65 1,800 38-2-2-9 21.13 1,800 38-2-3-3 31.60 1,600 38-2-lv-lt 99.58 1,650 38-2-2-!; 115.80 1,700 38- 2- 8- it More than 200.00 1,600 38-2-8-2 ....do.... 200.00 1,550 38-2-6-3 .12 1,000 38-2-7-6 1.33 800 38-2-1-6 11.58 600 38-2-2-6 13.55 800 38- 2- ^- 3 19.75 500 38-2-5-6 38.1*3 1*50 38-2-3-6 1*3.25 500 38-2-6-2 97.27 350 38-2-lt-2 127.22 1*00 38-2-3-2 179.18 350 38-2-8-3 : More than 200.00 320 Not broken 0.0098 : : .0091 : : .0105 : : .0073 : : .0096 : : .OO83 : : .OO83 : : .008U : : .0096 : : .0034 : : .0102 : : .0102 : : .0099 : 0.0280 : 0.0166 .0106 : .0308 : .0186 .009t : : .0100 : : .OO83 : : .0091 : : .0098 : : .0090 : : .0102 : : .0104 : : .0108 : : .0100 : : .0101 : .0258 : .0161 -Test data for comparison with the more comprehensive test data (table 28) obtained in run 1 with adhesive 38 manufactured by another manufacturer. 2 The control strength was the average strength, at 72° to 76 F. and at a loading rate of 300 pounds per minute, of 3 specimens selected from the same bonded panel as the test specimen. 3 ""The creep was measured by observing with a measuring microscope the offset of a fine line scribed across the edge of the bonded joint. Measurements were taken of the amount of creep after 200 hours of loading. These measurements were made both while the specimen was under load and following 1 week of room- temperature conditioning after the load was removed. S'M 89817 F Table 30. — Test data obtained In long- time- loading tests of l/2-lnch lap-Joint specimens of 0.061*- Inch 2UT-T3 clad aluminum alloy bonded with adhesive ll Specimen No. Duration of stress Constant 6treeB Percentage of control . strength- Type of failure Adhesion: Cohesion to metal: FillL thickness Creep measurement- After loading After loading and conditioning Hours P. 6.1. Per c ent : Per c ent 1*1-8-1* 0.01 3,600 1*1-5-9 .01 3,600 Ul-3-U .03 3,200 1*1-2-9 .52 3,300 1*1-1-3 .1*0 3,300 1+1-5-1* .75 3,500 Ul-UU 1.00 3,800 1*1-7-9 1.22 3,1*00 1*1-6-9 U.00 3,300 1*1-7-3 33.53 3,100 1*1-7-1* 111*. 67 3,380 1+1-2-1* 181.67 3,000 1*1-1-1* More than 200.00 3,200 1*1-5-3 . . . .do. . . . 200.00 3,200 1*1-1*- 9 . . . .do. . . . 200.00 3,200 fcl-3-9 ....do.... 200.00 2,900 1*1-6-1* .. . .do. . . . 200.00 2,600 1*1-9-2 .03 700 Ul-U-2 .68 1,200 1*1-8-6 .77 700 1*1-2-3 .93 900 1*1-2-2 .98 1,000 1*1-3-2 1.50 600 1*1-5-2 I.67 1,000 1*1-1-2 3.02 : 800 Ul-6-3 16.77 500 1*1-6-6 27.17 : 6OO Ul-l*-3 51*. 87 1*00 1*1-8-2 63.OO : 325 1*1-2-6 81.17 : 350 1*1-6-2 : More than 200.00 : 300 1*1-5-6 :....do.... 200.00 275 Under test at 72° to 76" F. 102.1 91.5 81*. 8 91*. 7 100.2 88.9 96.0 93.6 95.1* 85.3 97.7 87.0 97.3 81.2 81.0 76.6 75.0 Under test at 178 : 25 75 : : 10 90 : : 15 85 : : 10 90 : : 10 90 : : 10 90 : : 10 90 : : 10 90 : : 5 95 : : 5 95 : : 5 95 : : 10 90 : : Not broken : 9° to 182 ' F. 10 90 s 95 5 95 10 90 10 90 15 85 5 95 10 90 10 90 10 90 20 . 80 25 75 25 75 Not b: -oken ....d( 3 Inch Inch Inch 0.0081 : : .0066 : : .0055 : : .001*1 : : .0055 : : .0058 : : .0035 : : .0036 : : .0062 : : .001*2 : : .0037 : : .0020 : : .001*0 : 0.00C1* : O.OOOO .0055 : .0000 : .0058 : .0000 : .0039 : .0000 : .0076 : .0000 : .008- .0050 .0056 .0033 .OOW* .0067 .0036 .0070 .0083 .0095 .0029 .0089 .00W* .0066 .0060 0033 0027 0032 0006 ■=The control strength was the average strength, at 72° to 76° F. and at a loading rate of 300 pounds per minute, of 3 specimens selected from the same bonded panel a6 the test specimen. 2 -The creep was measured by observing with a measuring microscope the offset of a fine line scribed across the edge of the bonded Joint. Measurements were taken of the amount of creep after 200 hours of loading. These measurements were made both while the specimen was under load and following 1 week of room- temperature conditioning after the load wa6 removed. 7V B 1638 » Figure 1. --Test chamber and temperature -controlling apparatus used for maintaining test specimens at 178° to 182° F. during shear strength tests. Z M 79837 F Figure 2. --Test chamber used for maintaining test specimens at -65° to -70° F. during shear strength tests. Z M 89720 F Figure 3. --Test grips used for holding lap-joint speci- mens of aluminum during fatigue strength tests. Z M 83456 F ^1* ffz ROUNDING ' I o 4 ' D. DRILLED 4 a REAMED Z M 85231 F D. DRILLED S REAMED Figure 4. --Detailed drawing of teat grips used for holding lap-joint specimens of aluminum during fatigue strength tests. Figure 5. --Direct-stress fatigue machine with test grips and specimens in place for determination of the fatigue strength of adhesive bonds in aluminum lap-joint specimens. Z M 83455 F Figure 6. --Test chamber used for maintaining test specimens at -65° to -70° F. during fatigue strength tests. Z M 89719 F Figure 7. --Cantilever loading apparatus used in determining the long-time strength of adhesive bonds in aluminum lap-joint specimens. Z M 85062 F Figure 8. --Arrangement of test specimen, test fixture, and thermo- statically controlled heating chamber in the test apparatus for determining the long-time strength of adhesive bonds in aluminum lap-joint specimens. Z M 85063 F Figure 9- --Arrangement of measuring microscope on cantilever load- ing apparatus for measuring the deformation of adhesive bonds in aluminum lap-joint specimens during long-time loading. Z M 85064 F s * jh 1 J, , < 5 i v ~r* — 1 f+ r / 0/ i /< b / — f / t -N I Uj tv B — X — <*: = ki Q, ^ s ^ — Os (V 'cr X 4 T a/ I 1 — -/- / 0/ Q al Q * :* s 5u,^ K IN 6 IN M IN SE FAIL Uj — - — - (»\ Uj •J *f 5J ^c 2££$^ • ? i * — K = 1 Pr\ — A— ^ i ? ft < s c J * Q 8 II in u N 1 (D 3 (fl - > (fl (fl U • •-» T. 2 a '. E — .r U efl - 1 CO £ II ■ ft <* u ir. in 1 — 1 jq (A - 9 c TJ (0 II X, H > ^ w u 3 >N » X u _ u II "- TJ ■ c 3 -J 0: 00 E 3 a a II h (fl O (C = 3 •~4 2 ■ cr *"™^ - c CO ^ 5 u 3 3 - £ M II O Q K (fl — - V a) a T3 V) U go C UJ ** ~~ U 3 fin IS H Z ^ u V) c *> ^> >> *r '. <>> u N ■0 ^. v— c V ■ u m 1 II 4) a h J3 II . a E 3 c 1 Ej u - c Ifl u M ^ CO a (fl (0 j. 4-* M ■ - (fl 1 > a II 00 (0 2 11 u 3 u D M Q> 1 CO c :. co ^. ■ - M 01 1 5 — (fl (fl 8 a " 2 V u, ■ h ■^ 41 c If) w E 3 — 3 r- CQIE d Cl'S'd) S S3 HIS 03 IV 3d 3d HinHIIXVHI j ► i / ? ^ /• -V< V- 1 ► / ( >— y~x c / ° —to — ■I- - o — - o — ■ 03 1 i 1 /m. -/* I i • V ? A 1 — T~^ ) / / c > y — ^ £ 5 . c> kit: QCQ ^ ki 5, 5$ -kj Uj URE IN ED IN f NOT FA h"^ : 3^5 vc £ u: o> o# ?i _ o - N. \ 1 , i O ^ (lOdlNOD JO lN30d3d) SS3&1S 03AV3d3d INDIA! IXVW 9 1 CO CO t > ft »1 1) CO (X It 2 1) ro £ ~ > 4-> k o * 00 T, c <© >< rQ u CU o ^ ■M V ^1 —> CO X . — 1 o u ■H u 3 >< c ■n u ki cu •— < 3 ccJ 60 r CU -a c CO a u j: 4-> it CO u 3 a M T3 Q o h 01 1! c o a i 0) CO 3 -H 4-1 (X X CU CM a o ■ cu co a CO co LI | 1 -■» u 9- a) CD CU 4-. rt V CO >-i > , "mi CU h 4-> CO c V CO o CO DC CU o 1 (0 V-l — - a) n. o CO 2 h 2 i CU CO £ -i IM CO •o 00 2 3.000 2.000 I 000 -•— - - o ^~^. ! "v K ">.| L O EGEND: - FAILURE - FAILURE - FAILED *- DID ivor 1 IN BOND •^H IrST" _._ l • — o o IN METAL IN SET-UP FAIL tf£* A \ o,uuu 4,000 3 t ooa p , ? s 2,0Qa 3 Cr s 1,000 ^2=S" B II 1 10 10' I0 3 I0 4 I0 5 CYCLES TO FA I LURE I0 6 10' 10° Figure 12. --A. S-N (stress -number of cycles to failure) fatigue curve at room temperature (75° F. ) for single-lap specimens of 24S-T3 clad aluminum alloy bonded with adhesive 25-26. B. S-N fatigue curve at -65° to -70° F. for specimens bonded with adhe- sive 25-26. Maximum repeated stresses are expressed in pounds per square inch. The stress ratio was 0. 10. ULT\ 80 70 60 50 40 in L - o • E6EN :x> ~ rAlLunc nv auivu " - FA/ LURE IN METAL - FAILED IN SET-UP 6* - DIC > / SIOT FAIL i set A 1 J . &- JOi. 100 10 102 ZM 9<">n6 F I0 3 I0 4 I0 5 CYCLES TO FAILURE I0 6 I0 7 108 Figure 13. --A. S-N (stress-number of cycles to failure) fatigue curve at room temperature (75° F. ) for single-lap specimens of 24S-T3 clad aluminum alloy bonded with adhesive 25-26. B. S-N fatigue curve at -65° to -70° F. for specimens bonded with adhe- sive 25-26. Maximum repeated stresses are expressed as per- centages of the control strength. The stress ratio was 0. 10. s.uou 4,000 3,000 2,000 £ 1,000 5° 1 -.. *•- *•>. \ V % *£z~ J D legend: -failure in adhe SIVl ' IN ME 10ND TAL ,<3 « » -7 "£/VS ON FAI LURE "•*■» A 1 (ROOM TEl\ llllll 1 1 1 IPEf- Mil 1ATURE) 1 1 1 5,000 J,<%>0 2,000 l,0OO •N •»» 1 *N ^ '» ^w s > "S v. :■ hi 't,° : ^ • ^ • c \» 1 ? r- / Mill 1 F \ Z M 9T»19 F *? I0 2 I0 3 10" 10 s CYCLES TO FAILURE 10 s JO' 10' Figure 14. --A. S-N (stress -number of cycles to failure) fatigue curve at room temperature (75° F. ) for single-lap specimens of 24S-T3 clad aluminum alloy bonded with adhesive 34. B. S-N fatigue curve at -65° to -70" F. for specimens bonded with adhe- sive 34. Maximum repeated stresses are expressed in pounds per square inch. The stress ratio was 0. 10. The test points with arrows attached are for specimens that did not fail. I k. £ CO <0 3 1 IUU 90 80 70 60 50 40 30 20 IO O ■j ^v -» V \ >S ■ legend: o - failure in adhesive bond • - 7 ENSIC N FAI LU RE 1 N ME TA L II • A (ROi 1 1 1 OM TEMPEh urn i mi 1ATURE) mi i i too 90 80 70 60 50 40 30 20 10 ^ » v> 111 "S N ■ 'V, V V k > hi v. «.. y y i: • B f-7i 1 I 0° F Mill ) .1 1 10 io e to 3 10* 10 s CYCLES TO FAILURE 10* 10' I0 l Z M 90218 F Figure 15. --A. S-N (stress-number of cycles to failure) fatigue curve at room temperature (75° F. ) for single-lap specimens of 24S-T3 clad aluminum alloy- bonded with adhesive 34. B. S-N fatigue curve at -65* to -70* F. for speci- mens bonded with adhesive 34. Maximum repeated stresses are expressed as percentages of the control strength. The stress ratio was 0. 10. The test points with arrows attached are for specimens that did not fail. r ^ »J I to ^ S 5 5^- i^j — ^ to 5 cv D S o • In ~ to i ■) u x > C "*i J 1 *- - ^ «j — i to ^Z *£ — — $r ^ ^ 5 jiu £ iS : ^ S = to ^ 5 £ * - i to =§E to - > -1, o V. ^ ( 1 S d) SS3U1S Q3±V3d3d wntVIXWV X h 01 CO 'J i- <""> * * > -a VI 3 ., H «3 > hi fl) to i; c °- XI hi E3 o C x; V R) x -a - i- ■£ C ti ■^- E 2 41 (0 «) ie >1 -0 £ * ■ Q rt 1? oj o. a x 4) O > X> S IN £ a) — «i S 1 oo In *» 00 $ 3 SP F o 00 o o a to 5 3 I s - >- a g «J c 1 *■• 00 ^. o Z 3 o *- 5d •5 XI X •- ■» to | * V ! ^ to "3 "o > a ►^ •* E d »> $ to U CO 3 £ u | a *3 OJ fl) 3 2 R) t- a £ in V c *-* XI V ro a) E £ ^r « u s 5 i« w .> 00 * v 00 o ^H gg O. •. 4) u ••"* 0) ■ XI a) iri x; T. V 43 fl) c PO <-• H u ■•^ XI c> 2 'So 4» 5 > XI co a - X) ao C X u X 4-1 03 c 09 CURVE - Ui 9 | - - - ££W l/f- /J £W£ SI VE 35 50 40 30 WHESIVE 3. 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