The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
Sayed A. Nassar - One of the best experts on this subject based on the ideXlab platform.
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Effect of autoclave cure time and bonded surface roughness on the static and fatigue performance of polyurethane Film Adhesive Single lap joints
International Journal of Adhesion and Adhesives, 2019Co-Authors: Isotta Morfini, Luca Goglio, Giovanni Belingardi, Sayed A. NassarAbstract:Abstract This study investigates the effect of autoclave cure time and bonded surface roughness on the static and fatigue performance of Film-Adhesive single lap joints. Joint static performance is assessed in terms of its load transfer capacity in a quasi-static tensile-shear test to failure. Effect on fatigue life under a mean and cyclic tensile-shear amplitude is also investigated. Two levels autoclave cure (soak) time and two levels of bond surface roughness are investigated. All other autoclaving process variables are kept constant; namely, the ramp rate of temperature rise/cooling, pressurization/depressurization, as well as the cure temperature and cure pressure levels. Test joints are made of aluminium-aluminium or aluminium-magnesium adherends, joined with a polyurethane Film Adhesive. The results suggest that: an increase of the surface roughness is beneficial to static strength and detrimental to fatigue strength; an increase of the autoclave soak (cure) time is beneficial both to static and fatigue strength. Test data, failure mode analysis, discussion, observations and conclusions are provided.
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Process variable effect on the strength of autoclave-bonded Film Adhesive joints
Journal of Adhesion Science and Technology, 2019Co-Authors: Shraddha Jagatap, Sayed A. Nassar, Abbas Razavykia, Belingardi GiovanniAbstract:AbstractThis study investigates the effect of five independently-controlled process variables and variable combinations on the shear strength of autoclave-bonded Film Adhesive joints. Studied variables include the cure temperature, cure pressure and their respective ramp rates, as well as the duration of cure time. A full factorial design of experiment (DoE) at two levels for each variable is conducted with 3 replicas of each test. Test coupons are made of two layers of polycarbonate lexan that are autoclave-bonded using aliphatic polyether Film Adhesive (Huntsman PE399). Two set of test joints are used for generating test data on shear strength and failure mode. Bonded joints in the first set are tested prior to any environmental cycling, in order to generate baseline data on joint shear strength and failure mode. However, samples from the second set of autoclave-bonded joints were heat-cycled, in an environmental chamber at high relative humidity, prior to testing for shear strength. Test data on shear ...
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Effect of Autoclave Process Variables on Film Adhesive Bond With Polycarbonate Adherends
Volume 2: Computer Technology and Bolted Joints, 2018Co-Authors: Shraddha Jagatap, Sayed A. NassarAbstract:This study investigates the effect of autoclave curing process variables on the bond strength between Film Adhesive and polycarbonate adherends. Bond strength is measured in terms of the tensile shear load transfer capacity (LTC). Studied variables include cure temperature, cure pressure and their respective rates as well as the duration of cure time. Test coupons are made of two layers’ polycarbonate lexan adherends that are autoclave-bonded using aliphatic polyether Film Adhesive (Huntsman PE399). The relative significance of variables and variable combinations are investigated for their effect on the bond strength. Experimental test data shows interaction between autoclave variable cure temperature in combination with cure time, temp ramp rate and pressure ramp rate have significant effect on bond strength and failure mode.
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Effect of Autoclave Cure Time and Surface Preparation on Film Adhesive Bond in Lightweight Material Joints
Volume 2: Computer Technology and Bolted Joints, 2018Co-Authors: Isotta Morfini, Luca Goglio, Giovanni Belingardi, Sayed A. NassarAbstract:This study investigates the effect of cure time and surface roughness on mechanical performance of single lap joints (SLJ). Test joints are made of aluminum/aluminum or aluminum/magnesium adherends that are autoclave-bonded using a commercially available Film Adhesive. Joint mechanical performance is assessed in terms of the static load transfer capacity (LTC), fatigue life and failure mode. Except for the cure time, all the rates of the other autoclave-bonding parameters are kept constant; namely, the level of cure temperature and pressure, as well as the rates of autoclave heating, cooling, pressurization and depressurization. Test data, failure mode analysis, discussion, observations and conclusions are provided.
Alan Baker - One of the best experts on this subject based on the ideXlab platform.
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Reinforcement of the F-111 wing pivot fitting with a boron/epoxy doubler system—materials engineering aspects
Composites, 1993Co-Authors: Alan Baker, R.j. Chester, M. J. Davis, J D Roberts, J.a. RetchfordAbstract:Abstract Local regions in the D6ac steel F-111 wing pivot fitting suffer plastic deformation during the cold proof test employed to screen out flaws in the steel components of the airframe. This deformation produces residual stresses which can lead to a fatigue cracking problem in service. This paper describes materials engineering aspects of a programme undertaken at the Aeronautical Research Laboratory to develop an advanced fibre composite doubler system aimed at reducing the strain in these regions during the cold proof test and also to reduce cyclic strain during subsequent operation of the aircraft. The doubler system chosen is boron/epoxy (over 120 plies thick) bonded with a structural Film Adhesive. Aspects described include selection and characterization of composite and Adhesive bonding system, doubler fabrication and application technology and evaluation of a representative doubler specimen. Use of the doubler system has been demonstrated to reduce the strain in the critical regions by over 30%, confirming design predictions.
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REPAIR EFFICIENCY IN FATIGUE‐CRACKED ALUMINIUM COMPONENTS REINFORCED WITH BORON/EPOXY PATCHES
Fatigue & Fracture of Engineering Materials & Structures, 1993Co-Authors: Alan BakerAbstract:This paper describes studies on fatigue crack propagation in cracked aluminium alloy (2024 T3) panels repaired with boron/epoxy patches, Adhesively bonded with either an epoxy-nitrile Film Adhesive or an acrylic Adhesive. Studies were undertaken to assess the effect on patching efficiency of (a) disbonding of the patch system and (b) test temperature. A simple model is proposed for estimating the reduction of patching efficiency due to cyclic disbonding of the reinforcement. In the elevated-temperature tests it was found, unexpectedly, that patching efficiency in panels patched using the Film Adhesive was unaffected by temperatures up to 100°C.
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The Development of a Boron/Epoxy Doubler System for the F111 Wing Pivot Fitting - Materials Engineering Aspects
1991Co-Authors: Alan Baker, J.a. Retchford, R.j. Chester, M. J. Davis, J D RobertsAbstract:Local regions in the D6AC steel F111 wing pivot fitting suffer plastic deformation during the cold proof test employed to screen out flaws in the steel components of the airframe. This deformation produces residual stresses which can lead to a fatigue cracking problem in service. This paper describes materials-engineering aspects of a program undertaken at ARL to develop an advanced fibre composite doubler system aimed at reducing the strain in these regions during the cold proof test and also to reduce cyclic strain during subsequent operation of the aircraft. The doubler system chosen is boron/epoxy (over 120 plies thick) bonded with a structural Film Adhesive. Aspects described include selection and characterisation of composite and Adhesive bonding system, doubler fabrication and application technology and evaluation of a representative doubler specimen. Use of the doubler system has been demonstrated to reduce the strain in the critical regions by over 30%, confirming design predictions.
David R Arnott - One of the best experts on this subject based on the ideXlab platform.
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The Effect on Mechanical Properties of Void Formation During Vacuum Bag Processing of Epoxy Film Adhesives
1995Co-Authors: David R Arnott, Peter J Pearce, Richard J Chester, Anthony Camilleri, Alan R Wilson, John BergAbstract:Adhesively bonded repairs to aircraft structural components are frequently applied using vacuum bag cure procedures. Void formation in the Adhesive during vacuum bag processing is of concern, particularly as voids result from a variety of causes and the degree of voiding in the Adhesive is unpredictable. Confidence in bond integrity is usually evaluated using single overlap shear test specimens, surface prepared and cured under identical conditions to those of the repair bond. This paper considers void formation in Cytec FM300 epoxy Film Adhesive on grit blasted adherends treated with an epoxy-silane coupling agent. The conclusions drawn from standard overlap shear, peel and durability tests suggest that a microvoid content of up to 20 % of the surface area does not significantly degrade these mechanical properties. However, the single overlap shear test must be used with caution as the joint configuration and the Adhesive fillet have a significant influence on failure loads and can be responsible for the rejection of satisfactory bonds.
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Void Development in an Epoxy Film Adhesive During Vacuum Bag Cure
1995Co-Authors: Alan R Wilson, Max R Kindermann, David R ArnottAbstract:The effect of vacuum pressure on the transport and formation of voids in two epoxy Film Adhesives (FM 73 and FM 300) has been studied. Bonds were formed between glass adherends and glass and grit-blasted aluminium alloy adherends. The formation and behaviour of the voids during the cure cycle was recorded using a video camera and a video cassette recorder. Two sources of volatile materials leading to voids in the Adhesive were identified: a) volatile material within the Adhesive Film and b) volatiles trapped in the surface of grit-blasted metal adherends. Water appears to be the most important volatile in the Adhesive. The extent of voiding in a cured Adhesive bond was seen to vary between different batches of the Adhesive. Bonds formed between glass/glass adherends for one batch of FM 73 exhibited increased void area fraction above a partial vacuum of 500 millibar reaching 14% void area fraction at 1000 millibar. A different batch of FM 73 Adhesive exhibited very little voiding under all vacuum conditions used. The FM 300 Adhesive had less voiding at higher vacuum and suffered from incomplete compression of the Adhesive at lower vacuums. Bonds formed between the glass/metal adherends showed an increase in the void content of the Adhesive with the severity of the grit-blast.
Klaus Dilger - One of the best experts on this subject based on the ideXlab platform.
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laser surface pre treatment of cfrp for Adhesive bonding in consideration of the absorption behaviour
Journal of Adhesion, 2012Co-Authors: Fabian Fischer, Stefan Kreling, Peter Jäschke, Michael Frauenhofer, Dietmar Kracht, Klaus DilgerAbstract:The use of carbon fibre-reinforced plastics (CFRP) is growing significantly in all areas of lightweight construction. Thermosets like epoxy still build a major part of deployed matrix material. A suitable joining technology for CFRP is Adhesive bonding. However, the bonding performance is well reduced because of contaminations. To achieve full bond-strength, adhesion of the Adhesive to the components is essential. One innovative method for surface pre-treatment is laser radiation. Former investigations show that an important parameter is the absorption. As a result of that, a UV laser (wavelength of 355 nm) and a CO2 laser (wavelength of 10600 nm) were used to pre-treat specimens manufactured from 120°C curing epoxy. The focus is to achieve a selective removal of resin without impairing the fibres. Lap-shear specimens have been pre-treated, bonded with an one component epoxy Film Adhesive and tested. The laser pre-treated specimens achieve the same bond strength as references prepared by manual abrading. ...
J D Roberts - One of the best experts on this subject based on the ideXlab platform.
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Reinforcement of the F-111 wing pivot fitting with a boron/epoxy doubler system—materials engineering aspects
Composites, 1993Co-Authors: Alan Baker, R.j. Chester, M. J. Davis, J D Roberts, J.a. RetchfordAbstract:Abstract Local regions in the D6ac steel F-111 wing pivot fitting suffer plastic deformation during the cold proof test employed to screen out flaws in the steel components of the airframe. This deformation produces residual stresses which can lead to a fatigue cracking problem in service. This paper describes materials engineering aspects of a programme undertaken at the Aeronautical Research Laboratory to develop an advanced fibre composite doubler system aimed at reducing the strain in these regions during the cold proof test and also to reduce cyclic strain during subsequent operation of the aircraft. The doubler system chosen is boron/epoxy (over 120 plies thick) bonded with a structural Film Adhesive. Aspects described include selection and characterization of composite and Adhesive bonding system, doubler fabrication and application technology and evaluation of a representative doubler specimen. Use of the doubler system has been demonstrated to reduce the strain in the critical regions by over 30%, confirming design predictions.
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The Development of a Boron/Epoxy Doubler System for the F111 Wing Pivot Fitting - Materials Engineering Aspects
1991Co-Authors: Alan Baker, J.a. Retchford, R.j. Chester, M. J. Davis, J D RobertsAbstract:Local regions in the D6AC steel F111 wing pivot fitting suffer plastic deformation during the cold proof test employed to screen out flaws in the steel components of the airframe. This deformation produces residual stresses which can lead to a fatigue cracking problem in service. This paper describes materials-engineering aspects of a program undertaken at ARL to develop an advanced fibre composite doubler system aimed at reducing the strain in these regions during the cold proof test and also to reduce cyclic strain during subsequent operation of the aircraft. The doubler system chosen is boron/epoxy (over 120 plies thick) bonded with a structural Film Adhesive. Aspects described include selection and characterisation of composite and Adhesive bonding system, doubler fabrication and application technology and evaluation of a representative doubler specimen. Use of the doubler system has been demonstrated to reduce the strain in the critical regions by over 30%, confirming design predictions.