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![]() Materials Sciences and Applica tio ns, 2011, 2, 458-464 doi:10.4236/msa.2011.25061 Published Online May 2011 (http://www.SciRP.org/journal/msa) Copyright © 2011 SciRes. MSA Optimization in Autoclave Process to Produce Durable Aluminium Composite Handoko Subawi Indonesian Aerospace Ltd, Bandung, Indonesia. Email: handoko@indonesian-aerospace.com Received September 22nd, 2010; revised May 1st, 2011; accepted May 11th, 2011. ABSTRACT The purpose of this paper is to characterize adhesive bonding performance through the fracture evaluation. Failure modes correlate to the bond strength, in which the weak bond of adhesion will be considered unacceptable in the air- craft manufacture certifica tion, whereas the cohesion bond as strong as adhesive itself is preferably accepted. The final quality of adhesive bonding process depends on several key variables during manufacturing. A good anodizing treat- ment is properly maintained in order to eliminate possible bond failures in the long term bond durability in service. This paper described the method to improve an adhesive joining for durable bonds through optimizing the process va- riable during autoclave curing. The process simulation utilized the drum peel test to describe the cohesive fracture phenomenon in which applicable on a daily load basis in commercial application. Keywords: Aluminium Composite, Adhesive B onding, Failure Mode, Cohesive Failure 1. Introduction Adhesive b onded panel is formed by an adhesive joining process between skins, its doublers and honeycomb core using a film adhesive which undergoes a physical or chemical hardening reaction. This reaction causes the parts to join together through adherence and cohesion strength. The final quality of adhesive bonding process depends on the several key variables during manufactu- ring. The honeycomb core must sufficiently compact with adhesive layer to join its cover skins and doublers. The application of metal bonding technology using a film adhesive in any case has some advantages compare to others metal joining concept. The main advantage of the adhesive joining compared to the welding, riveting, brazing and screw fastening is that the adhesive bonded load is distributed u niformly to the loading direction [1]. However, employing primer and film adhesive requires a proper handling and storage of these materials. Handling system of sensitive materials include the packaging in sealed bag, the supporting tool to maintain roll condition, its transportation to customer shop, and how to manage the time life of these materials. Adhesive bonded panel is widely used for primary composite structure in commercial aircrafts. The effect of surface preparation procedures and material systems on the aluminium surface chemistry subsequently correlates to the bond performance. A good anodizing process en- sures a high adherence grade between the aluminium skin surface and the cured primer coat. A number of characterization techniques to evaluate adhesive bonding quality include the surface appearance, the surface che- mistry, the surface energy, and the fracture evaluation. In the fracture evaluation, the only way to measure bond quality empowers the standard specimens for lap shear [2] and drum peel tests [3]. Most of bonding shops utilize these strength tests to qualify the bonding pro- cesses, meanwhile some researchers [4-9] focused on the efforts to improve quality of the adhesive materials. However, there is not an effective solution to provide a method to differentiate between the bond strength and the bond durability practically in commercial application. Failure mode correlates to the bond strength in which the weak bond of adhesion will be considered unaccept- able in the aircraft manuf acture certification, whereas the cohesion bond as strong as adhesive itself and also the inter laminar (structure) bond as strong as laminate itself are preferably accepted. For practical purposes, some researchers proposed a modification of metal to metal peel test called as a “rapid adhesion test” method that is a quick to assess the adhesion in which the backing adhe- rent clamped to while the peeling adherent is removed. ![]() Optimization in Autoclave Process to Produce Durable Aluminium Composite Copyright © 2011 SciRes. MSA 459 The failure mode represents poor bond of adhesion fail- ure and strong bond of cohesive failure [10]. A good anodizing treatment as the main process vari- able mostly eliminates bond failures in a long term bond durability in service. The aluminium surface does not only require clean, but also chemically active surface that is resistant to hydration. The possible bond failure modes are classified in the form of the adherents outside the joint, the cohesion failure of the adhesive, or the adhe- sion failure of the interface. Failure of the adherents out- side the joint may be achieved while using moderately thin adherent materials. The cohesion failure may be caused by an inadequate overlap length, or the presence of thermal stresses or void defects. While, the adhesion failure of the interface can be caused by an inadequate or ineffective surface preparation process. One important factor to improve adhesive bonds per- formance is a comprehensively effort to develop both the bond strength and the bond durability. The bond durabi- lity depends on the resistance of the adhesive to adherent interface against to water ingress. The resistance to hy- dration is established by the process used to prepare the surface of the adherents for bonding. The adhesive bond durability becomes an important topic since the publica- tion of the recommendation of Amendment FAR Section 25.605 proposed by Directorate General Technical Air- worthiness of Royal Australian Air Force [11]. The regu- lation is: 1) The methods of fabrication used must produce a consistently sound and durable structure. If a fabrication process (such as gluing, spot welding, or heat treating) requires close control to reach this objective, the process must be performed under an approved process specifica- tion that has been demonstrated to produce a structure that is strong and durable. 2) Each new aircraft fabrication method must be sub- stantiated by a test program that demonstrates that the process used is capable of producing a structure that is strong and durable. Some researchers argue that lap shear specimen is not capable to validate long term bond durability. The ser- vice history statistically describes that lap shear testing can not distinguish between a good and a bad processes. The metal bond durability can be validated through the wedge test that tolerates the specimen crack growth of an average of 0.50 inch and a maximum of 0.75 inch in one hour exposure to 60˚C and 95% RH [12]. However, a further recommendation offered an acceptance criteria requires more stringent than broad consensus where a crack growth length should be less 0.20 inch/24 hrs and 0.25 inc h/ 48 hrs, and also <5% adhesion failure [13]. Although it is confirmed that durable bonds of adhe- sive joining meet a wedge test criteria, however the wedge test is still considered less practical to be applied in daily load commercially to accompany the speed of the production rate. Actually, the wedge test is being applied when producing the first article or if any major chemical replenishment or solution dumping for revali- dation of the surface preparation process. In a commer- cial application, it is not easy to anticipate crack propa- gation less 0.15 inch/1.25 hour consistently in a climatic chamber at 95% RH. The wedge specimen does not only require long se- quential steps and enough processing period, but also requires a high care especially during specimen cutting to eliminate any vibration impact to the subsequent result anomalies indicated by an improper crack propagation length in this specimen. In daily load basis, practically, the preferably commercial test to validate the failure mode analysis is the drum peel specimen to configure the durability characteristics of the actual aluminium com- posite panels. This paper describes one of tactically im- provement for durable bonds of adhesive joining through optimizing the process variable during autoclave curing. 2. Key Variables in the Adhesive Bonding Process 2.1. Setting Single Parts Prior to Integration Setting or pre-fitting activity integrates precisely b etween honeycomb core and all required aluminium skins prior to surface treatment of the skins and all related single parts. The work of this sequent refers to the detail draw- ing and depends on the operator hands. The operators should ensure that all single parts have been completely pre-fitted. Commonly it requires the additional thickness allowance in the range of 0.30 mm until 0.50 mm during this pre-integration step. This additional thickness allowance is sufficiently re- quired to anticipate pressurization impact through the vacuum bagging of an aluminium composite panel. The utilization of the cover on the stopper contributes to maintain the final thickness and the surface uniformity or the smoothness of the aluminium composite panels. The required thermocouples are positioned at the leading and lagging point on the surface of the tool is to ease the con- trol during autoclave curing. The key indicator of the success of this pre-fitting is when the honeycomb core is capable to adhere to the film adhesive perfectly. 2.2. Environmental Factor to Materials The film adhesive and other related adhesives in the form of foam and primer are classified as materials that sensi- tive to time and temperature. These materials require a proper handling and storage system to provide the phy- sical mechanical properties for manufacturing the adhe- ![]() Optimization in Autoclave Process to Produce Durable Aluminium Composite Copyright © 2011 SciRes. MSA 460 sive bonded structure. The sensitive materials are stored in a cold storage to eliminate potentially polymerization before lay up process. Prior to cut and applied through dry lamination process, these materials should be condi- tioned to reach the lay up room condition between 18˚C until 24˚C and required relative humidity in the range of 55% to 75%. The adhesion failure is indicated by the absence of adhesive on one of the bonding surfaces. It may occur due to hydration of the chemical bonds which form in the molecular link between the film adhesive and the bond- ing surface. The adhesive bond between aluminiums will fail only if the anodized layer converts to the hydrated and causes the aluminium surface-to-adhesive chemical bonds to dissociate leading to non bond. The oven heat- ing after primer application ensures the adherence of primer on to anodized aluminium surface and enhances the adhesive adherence. Adhesive joining which is formed on surfaces which are chemically active and resistant to hydration will be durable in service. 2.3. Anodizing to Activate the Aluminium Surface In the view of human aspect, the causes of adhesion fail- ure should be anticipated through the well understanding of an appropriate surface preparation technique which is able to produce a chemically active surface resistant to hydration. The first preparation of aluminium skin before anodizing is manually cleaned to remove any anti corro- sion coating oil. Basically, aluminium surface treatment provides good bond durability involves a number of steps, namely: to degrease the whole surface through emulsion or alkaline cleaning, to remove the existing surface layer through deoxidizing and to establish an active surface in the anodizing bath which will form hydration resistant bonds with the adhesive or primer. The key indicator of the successful of this surface treatment and the primer application is that the primer will adhere perfectly on to the surface of the anodized aluminium skin. In contrary words, the inappropriate anodizing process will not provide a strong bond be- tween the primer layer to the anodized skin surface. The anodizing process is essential and must be performed sequentially to establish a durable bond. Many process specifications, reference books and rep air manuals d o not contain completely procedures to conform complete se- quence and consequently do not produce durable bond [14]. 2.4. Adhesive Bonding Technique Adhesive bond does not tolerate any contamination on aluminium surfaces prior to bonding. Any adhesion fail- ure which occurs in service is a direct result of the manu- facturing process. Certain types of gloves (such as nitrile gloves) reduce the surface energy after contact on alu- minium surfaces and subsequently reduce bond strength. In some cases the low surface energy is reflected in the reduced average fracture toughness and the change of the mode of failure. Both without gloves and contaminated gloves change the failure mode of the drum peel speci- mens [10]. In case of bonding on tight surfaces, the super thin fa- bric reduces tacky problem to ease adhesive bonding. Actually, this super thin fabric reinforces the film adhe- sive with a typical thickness of 0.010 inch (0.250 mm) such as FM-73M.OST.06 Cytec or thicker. The super thin fabric usually does not require a thinner film adhe- sive for metal-to-metal bonding. The contaminated super thin fabric will remain spots or specific smell and these are easily detected. The super thin fabric should be stored in dry sealed bag and free from any contamination. 2.5. Process Control during Autoclave Curing The autoclave facility is operated referred to a number of process parameters such as heat up rate, holding time and temperature, cooling down rate and the end temperature. The vacuum bagging is checked from any vacuum leak- age and maintained in a partial vacuum just before an application of the autoclave pressure. Partial vacuum is vacuum condition in which less to the maximum value of vacuum capacity. Meanwhile, vacuum indicator will drop if there is a leakage in the sealed bag. The lagging ther- mocouple that controls the slowest heating location of the bagging system should be placed in the proper place. The historical process control is recorded on the auto- clave recorder. The controlled parameters include the vacuum and pressure values. If any vacuum leakage is detected during the process, it will be indicated through the vacuum graph that moves abruptly to the edge side of rolling recorder and move to roll direction consistently at zero scale. The perfectly sealed fully or partially vacuum should be maintained at a constant value during curing cycle. The manufacturing adhesive bonded panel requires different pressure parameters for metal to metal bonding and sandwich panels. The metal to metal configuration requires a cure pressure of 3.0 bars, whereas the sand- wich metals needs a lower pressure around 1.7 to 2.0 bars. The drum peel at this range of results a consistently high strength for adhesive bond, but the historical data do not show consistently a perfect cohesive bonding espe- cially for sandwich structure. 3. Experimental Procedures 3.1. Methodology The experiment evaluated the performance of a crack ![]() Optimization in Autoclave Process to Produce Durable Aluminium Composite Copyright © 2011 SciRes. MSA 461 wedge compared to non crack wedge tests. The evalua- tion of non crack wedge test involved sequentially work steps by varying the process variables to examine its possible impact against to the cohesive failure pheno- menon. The sequentially experiment were performed to determine different types of roots dominantly cause the cohesive failure phenomenon in the aluminium compo - site panels. A number of steps involved in the experi- mental procedure as followed: 1) Evaluate the test specimen types to validate the most critical the bonding adherence variables among the peel, shear and drum peel specimens. The first step of this study utilized the expired and new film adhesive to select the most representative test to examine the alu- minium composite panels. 2) Identify how far the process parameter variation would induce the mechanical properties through destruct- tive test specimen by using the new film adhesive. The process variables include: a) incomplete cleaning in alk a- line bath and drying at room temperature, b) application of multi layer adhesive, and c) application of interlayer of aramid. 3) Identify the impact of slightly higher autoclave pressure against to the mechanical properties of the sand- wich panels. The process variables included: a) single film adhesive, b) interlayer of super thin fabric, c) used primed skin, and 4) interlayer of super thin fabric. 3.2. Cohesive Failure Criteria This study employed destructive specimens to explain the adhesive bonding phenomenon in the aluminium composite panels. The drum peeling specimens was cho- sen to measure the confidence level of the quality of this adhesive bonding strength. The specimens were firstly treated in an anodizing line and the primer adhesive of BR-127 Cytec was applied within 4-8 µm thickness. Further, this primed skin was fully dried in an oven at 120˚C during one hour, prior to bonding lay up using the film adhesive FM-73M.OST.06 Cytec at 0.010 inch (0.250 mm) thickness [15]. The drum peeling specimens were prepared using the cladded aluminium alloy LP-3140-T3. The upper skin (300 mm × 75 mm) and lower skin (240 mm × 75 mm) of specimen was approximately 0.5 mm thickness. The thickness of metal core 7.9-1/4-4ON was 12 mm [13]. The laboratory testing was conducted by Instron ma- chine. The bonding surface was also observed visually to check cohesively grade of film adhesive. The possibility of any cohesive failure area was checked with refer of the bonding surface profile of the destructive specimens using drum peel testing. The best adhesive bonding should be 100% cohesively b on ded. 4. Results and Discussion 4.1. Crack Wedge Test The validation of metal bond durability based on the wedge test ASTM D3762-03 that tolerated the crack wedge propagation length until 0.50 inch in one hour ex- posure to 60˚C and 95% RH. This validation was dif- fi- cult to be fulfilled consistently. Even, a further recom- mendation called out an acceptance criterion more strin- gent less 0.15 inch/hour. In Figure 1 the bare aluminium tended to show inconsistency result compare to clad alu- minium (Figu re 2 ). However, the root cause of this failure might be depend- ing on the specimen cutting prior to la- boratory test, rather than the surface treatment procedure. This crack wedge specimen applied stringent process variable of internal pressure at 6 bars during autoclave curing to obtain the adherence quality of the metal bond. The basic handicap executed this test type in the produc- tion line, if applied in daily load. The difficulty is h ow to maintain production speed when requires re-test proce- dure to pass the criteria tolerance. The possible re-test Figure 1. Crack wedge length of bare Al. Figure 2. Crack wedge length of clad Al. ![]() Optimization in Autoclave Process to Produce Durable Aluminium Composite Copyright © 2011 SciRes. MSA 462 may frequently be performed due to the result inconsis- tency. However, the application of this method either for processing the first article and revalidation after totally chemical replenishment was acceptable to ensure the whole control of a surface treatm ent prior to metal bonding. 4.2. Non Crack Wedge Test The tactically stratification intended to identify the most critical test to determine the adhesive bonding perfor- mance. By utilizing the expired and new film adhesive FM-73M OST.06 Cytec, the critical test type was subse- quently selected. Table 1 herein shows the values of three standard test specimens in which the drum peel test method became the most critical performance among the others. This table also shows that the peel and shear speci- mens still provide exciting values than the drum peel specimens although using the expired adhesive film. The utilization of new film adhesive results a higher strength value through the drum peel test compared to the peel test. It shows that the expired film adhesive ind icates out tolerance in performance based on the drum peel test rather than peel and shear test. The configuration of the peel and shear specimens represent metal to metal bond- ing in which the upper skin will press uniformly over bond surface. The utilization of the film adhesive FM-73M.OST.06 with the initial thickness of 0.25 mm tends to reach a bonding thickness between 0.050 mm to 0.200 mm in adhesive bonded panels after an autoclave curing process. However, the metal to metal bonding sufficiently utilizes the film adhesive FM-73M.OST.03 with an initial thickness of 0.125 mm. In this matter, the study focused on the drum peel test to examine a relationship between the process parameter and its failure mode characteristic of aluminium sand- wich panels. The experiment utilized the new adhesive film and in the same time with the surface preparation was simulated to do an improper cleaning in the a lkaline bath at lower temperature around 25˚C. The standard process in alkaline cleaning should be conducted at 65˚C in ‘Turco’ solution, and the anodized aluminium required an air drying at 60˚C. The ‘Turco’ solution used in this experiment actually was removed and replaced by a new non-chlorofluorocarbon and at a low temperature, NCLT solution operating in room temperature condition. The curing process utilized the autoclave internal pressure between 1.7 to 2.0 bars to cure these specimens. All sandwich specimens fulfilled minimum value of drum peeling strength of 400 N minimum. The double layers of film adhesive FM-73M OST.06 Cytec drastically proved higher value of mechanical strength in sandwich panels. In practical application, double layer of film adhesive was intended for rework purposes to fill a gap between core and cover skins. Un- fortunately, by accommodating the interlayer such as aramid pre-impregnated between two film adhesive lay- ers dropped its mechanical properties until 238 N, far less than the practical requirement of 400 N minimum (Table 2). Set of operating parameters were completely fulfilled during surface preparation to ensure the higher bond characteristic between the film adhesive and the primed aluminium skins. The autoclave operated with an internal pressure of 1.7 to 2.0 bars, and the drum peel specimen consistently passed the practical requirement, however the fracture characteristic after peeling test did not gua- rantee absolutely free of cohesive failure. The trial experiment was conducted applying higher pressure to the specimen by mean of the table press at around 3.0 bars and showed excellent adhesive bond without crash on the honeycomb core 7.9-1/4-4ON of 12 mm thickness. With refer to this parameter, then auto- clave operation was prepared to higher pressure than the common practice at 1.7 to 2.0 bars to gain higher adhe- sive bond to avoid adhesive failure. Further step was prepared the drum peel specimen us- ing the new film adhesive to be subsequently polymer- rized in the autoclave at the higher internal pressure be- tween 2.5 to 3.0 bars. Other variable was simulated for example an additional super thin fabric and trial used primed skin to evaluate each of adhesive bond perfor- mance. The applied pressure at 2.5 bars to 3.0 bars re- sulted clearly characteristic of peeling fracture. These peel specimen showed consistently 100% cohesive than Table 1. Identification of test specimens performance. Specimen ID No. 1102A 2502A 2303A Film adhesive configuration and specification 1 layer FM-73M.OST.06 1 layer FM-73M.OST.06 1 layer FM-73M.OST.06 Film adhesive life time expired expired new Peel strength, (>170 N) 247 330 342 Shear strength, (>27 MPa) 42 40 39 Drum peel strength, (>400 N) 299 66 520 ![]() Optimization in Autoclave Process to Produce Durable Aluminium Composite Copyright © 2011 SciRes. MSA 463 Table 2. Test specimens comparison at standard autoclave internal pressure. Specimen ID No. 1103A 1103B 1103C Film adhesive configuration and specification 1 layer FM-73M.OST.06 2 layers FM-73M.OST.06 1 layer FM-73M.OST.06 + aramid Film adhesive life time new new new Process variables in preparation before bonding Incomplete cleaning in alkaline and drying at room temperature multi layer adhesive fully interlayer of aramid Cut section photograph Drum peel strength, (> 400 N) 446 1722 238 (not comply) Autoclave internal pressure, bars 1.7 to 2.0 1.7 to 2.0 1.7 to 2.0 A-scan ultrasonic test Completely bonded Completely bonded Completely bonded Cohesive failure determination Not consistent Nearly 100% cohesive Nearly 100% cohesive Table 3. Test specimens comparison at higher autoclave pressure. Specimen ID No. 0604A 0604B 0604C Film adhesive configuration and specification FM-73M.OST.06/original skin FM-73M.OST.06 +Cerec +original skin FM-73M.OST.06 / used skin Film adhesive life time new new new Process variables in bonding lay up Standard Interlayer of super thin fabric Used primed skin Cut section photograph Drum peel strength, (> 400 N) 471 520 495 Autoclave internal pressure, bars 2.5 to 3.0 2.5 to 3.0 2.5 to 3.0 A-scan ultrasonic test Completely bonded Completely bonded Completely bonded Failure mode determination 100% cohesive/inter laminar bond 100% cohesive/inter lamina r bond 100% cohesive/i nter laminar bond the common practice less than 2.0 bars (Table 3). Additionally, the super thin fabric that was manually laid on film adhesive improved its mechanical properties up to 10% compared to the standard adhesive film. The super thin layer should be placed on the tacky side of the adhesive layer FM-73M.OST.06 Cytec at 0.010 inch (0.250 mm) thickness to ease the bonding application during manual lay up. In the other case, the used primed skin with the suffi- ciently peel strength at 495 N provided higher confidence to ensure the rework process. In this case, the rework configured one side skin removal and partially core re- placement. In this experiment, the used primed skin was treated in the similar anodizing process prior to bonding ![]() Optimization in Autoclave Process to Produce Durable Aluminium Composite Copyright © 2011 SciRes. MSA 464 application utilizing film adhesive FM-73M.OST.06. 5. Conclusions The first important step to provide excellent bond dura- bility involves the surface cleaning, the deoxidizing sur- face layer and the activating surface to form hydration resistant bonds with the primer and film adhesive. In fracture evaluation recently, the optimal measurement of adhesive bond still depends on lap shear and drum peel. Failure mode of the accepted adhesive bond preferably indicates cohesion bond as strong as adhesive itself or inter laminar bond as strong as laminate itself. The crack wedge extension to validate adhesive bond durability is considered less practical commercially if conducted on a daily load basis, and usually being ap- plied to produce the first article or to revalidate the sur- face preparation process. Practically, drum peel specimen configures bond durability characteristics. The applied slightly higher autoclave pressure between 2.5 bars until 3.0 bars proves clearly characteristic of 100% cohesive peeling fracture than the common practice less than 2.0 bars. REFERENCES [1] L. Dorn, “Adhesive Bonding—Terms and Definitions,” Training in Aluminium Application Technologies, Tuto- rial, Lecture 4701, Technische Universitat, Berlin, 2010. Internet Available: http://www.eaa.net/eaa/education/talat/lectures/4701.pdf [2] ASTM D 1002-01, “Standard Test Method for Apparent Shear Strength of Single-Lap-Joint Adhesively Bonded Metal Specimens by Tension Loading (Metal-to-Metal),” ASTM International, 2001. [3] ASTM D 1781-98, “Standard Test Method for Climbing Drum Peel for Adhesives,” ASTM International, 1998. [4] S. Hojabr and S. R. Tanny, “Low Activation Tem- perature Adhesive Composition with High Peel Strength and Cohesive Failure,” United States Patent No. 6855432, E. I. du Pont de Nemours and Company, Wilmington, DE, 15 February 2005. [5] T. Takano, “Method to Improve High Temperature Co- hesive Strength with Adhesive Having Multi-Phase System,” United States Patent No. 7160946, National Starch and Chemical Investment Holding Corporation, New Castle, DE, 9 January, 2007. [6] J. C. Engelaere, “Bonding Composition with Cohesive Failure,” United States Patent Application No. 200702 12504, Soplaril, 1 rue de l’Union, Rueil Malmaison, France, 13 September 2007. [7] S. Kozakai, N. Ichiroku, A. Suzuki and T. Shiobara, “Adhesive Composition and Adhesive Film,” United States Patent No. 7364797, Shin-Etsu Chemical Co., Ltd., Tokyo, Japan, 29 April 2008. [8] S. Hamano, “Adhesive Film,” United States Patent Appli- cation No. 20090286073, Kyodo Giken Chemical Co., Ltd, Saitama, Japan, 19 November 2009. [9] A. Nishiura, H. Sugihara and K. Abe, “Adhesive Prepara- tion,” United States Patent Application No. 20100041758, Ono Pharmaceutical Co., Ltd., Osaka-shi, Japan, 18 Febru- ary 2010. [10] B. D. Flinn, F. Ohuchi, M. Phariss, J. Satterwhite, J. Au- bin and C. Keenen, “Improving Adhesive Bonding of Composites through Surface Characterization,” The Joint Advanced Materials and Structures Center of Excellence, CECAM, and AMTAS, University of Washington, 2010. http://depts.washington.edu/amtas/ev-ents/jams_08/21.Fli nn.pdf [11] M. J. Davis, “FAA Workshop on Best Practice in Adhe- sive Bonding, Principal Research Scientist,” Directorate General Technical Airworthiness, Royal Australian Air Force, 2010. http://www.niar.wichita.edu/NIARWorkshops/LinkClick. aspx?fileticket=iGBXdAGtWEk%3D&tabid=104&mid= 569 [12] ASTM D 3762-03, “Standard Test Method for Adhe- sive-Bonded Surface Durability of Aluminum (Wedge Test),” ASTM International, 2003. [13] M. J. Davis and D. A. Bond, “The Importance of Failure Mode Identification in Adhesive Bonded Aircraft Struc- tures and Repairs,” Aircraft Structural Integrity Section, Directorate General of Technical Airworthiness, Royal Australian Air Force, Amberley Detachment, 501 Wing, RAAF Amberley 4306, Australia, RAAF Williams, Mel- bourne 3027, Australia, 2010. http://www.adhesionassociates.com/papers/46%20Import ance%20of%20Failure%20Mode%20Indentification%20I CCM%2012%20Paris.pdf. [14] D. R. Arnott, A. R. Wilson, A. N. Ride r, C. L. J. Olsson, L. T. Lambrianidis, P. J. Pearce, M. J. Davis and G. Swan, “Research Underpinning the Adherent Surface Prepara- tion Aspects of the RAAF Engineering Standard C5033,” International Aerospace Congress, Sydney, 25-28 Febru- ary 1997. [15] Cytec Engineered Material Ltd., “Primer Adhesive and Film Adhesive,” Technical Data Sheet, Arizona, 2008. http://www.cytec.com/ |