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Li C Rendle - One of the best experts on this subject based on the ideXlab platform.
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the mechanical theory behind the Peel test
Energy Procedia, 2014Co-Authors: Ulrich Eitne, Li C RendleAbstract:Abstract The Peel test is a very simple and fast method to determine the adhesion of interconnector ribbons to solar cell metallizations. It is part of the solar cell standard DIN EN 50461 and is, due to its ease of use, widely accepted to qualify cell metallizations and the soldering process. In the standard a force of 1 N per mm of joint width is specified but other relevant quantities are missing, for example the Peeling angle. We show that this lack of specification enables the manipulation of Peel Testing results. We therefore apply the mechanical theory of Kinloch [1] where measured Peel forces are translated into adhesive fracture energies GA. The fracture energy is a geometry-independent parameter that describes the energy to break the interfacial bondings at the Peel front. It incorporates the dimensions of the ribbon and its stress-strain-curve. We perform 86 Peel experiments at 90°, 135° and 180° of ribbons on continuous front side busbars of cells from one stringing batch. While the median forces for 90°(3.07 N), 135°(2.35 N) and 180°(3.39 N) differ by up to 30.4% we find the median adhesive fracture energies to deviate by only 17.4%. Using the same adhesive fracture energy (260 J/m2) for a 45° Peel test we expect Peel forces of 7.45 N which is factor 2.4 (2.2) higher than the 90° (180°) Peel forces.
Glenn Daehn - One of the best experts on this subject based on the ideXlab platform.
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Joining Aluminium Alloy 5A06 to Stainless Steel 321 by Vaporizing Foil Actuators Welding with an Interlayer
MDPI AG, 2019Co-Authors: Shujun Chen, Anupam Vivek, Yu Mao, Jun Xiao, Glenn DaehnAbstract:Direct aluminium–stainless steel joints are difficult to create by the vaporized foil actuator welding (VFAW) method because brittle intermetallic compounds (IMCs) tend to form along the interface. The use of an interlayer as a transition layer between the two materials with vast difference in hardness and ductility was proposed as a solution to reduce the formation of the IMCs. In this work, VFAW was used to successfully weld sheet aluminium alloy 5A06 to stainless steel 321 with a 3003 aluminium alloy interlayer. Input energy levels of 6 kJ, 8 kJ, 10 kJ, and 12 kJ were used and as a trend, higher energy inputs resulted in higher impact velocities, larger weld area, and better mechanical properties. In lap-shear and Peel Testing, all samples failed at the interface of the interlayer and target. At 10 kJ energy input, flyer velocities up to 935 m/s, lap-shear peak load of 44 kN, and Peel load of 2.15 kN were achieved. Microstructure characterization and element distribution were performed, and the results show a wavy pattern created between the flyer and interlayer which have similar properties, and the interface between the interlayer and target was dominated by element diffusion and IMCs identified mainly as FeAl3 and FeAl. The results demonstrate VFAW is a suitable joining method for dissimilar metals such as aluminium alloy and stainless steel, which has a broad and significant application prospect in aerospace and chemical industry
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Impact Welding of Aluminum to Copper and Stainless Steel by Vaporizing Foil Actuator: Effect of Heat Treatment Cycles on Mechanical Properties and Microstructure
Metallurgical and Materials Transactions A, 2015Co-Authors: Anupam Vivek, Steven Hansen, Jake Benzing, Mei He, Glenn DaehnAbstract:This work studies the mechanical property effect of microstructure on impact welds of aluminum alloy AA6061 with both copper alloy Cu 110 and stainless steel AISI 304. AA6061-T6 and T4 temper aluminum sheets of 1 mm thickness were launched toward copper and stainless steel targets using the vaporizing foil actuator technique. Flyer plate velocities, measured via photonic Doppler velocimetry, were observed to be approximately 800 m/s. The welded aluminum-copper samples were subjected to instrumented Peel Testing, microhardness Testing, energy-dispersive X-ray spectroscopy, and scanning electron microscopy. The welded joints exhibited cracks through their continuous intermetallic layers. The cracks were impeded upon encountering a ductile metallic wave. The welds created with T6 temper flyer sheets were found to have smaller intermetallic-free and wavy interface regions as compared to those created with T4 temper flyer sheets. Peel strength tests of the two weld combinations resulted in failure along the interface in the case of the T6 flyer welds, while the failure generally occurred in the parent aluminum for the T4 temper flyer welds. Half of the T4 flyer welds were subjected to aging for 18 h at 433 K (160 °C) to convert the aluminum sheet to the T6 condition. Although the aged flyer material did not attain the hardness of the as-received T6 material, it was found to be significantly stronger than the T4 material. These welds retained their strength after the aging process, and diffusion across the interface was minimal. The welded aluminum-stainless steel samples were analyzed on a more basic level than aluminum-copper samples, but were found to exhibit similar results.
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Vaporizing Foil Actuator Welding of AA6061 With Cu110: Effect of Heat Treatment Cycles on Mechanical Properties and Microstructure
Volume 2: Processing, 2014Co-Authors: Anupam Vivek, S.r. Hansen, Glenn DaehnAbstract:This work aims to study the effect of microstructure of the weld between aluminum alloy AA6061 and commercially pure copper, Cu 110, on its mechanical properties. AA6061-T6 and T4 aluminum sheets of 1 mm thickness were launched towards copper targets using the Vaporizing Foil Actuator (VFA) tool operating at 8 kJ input energy level. Flyer plate velocities, measured via photonic Doppler velocimetry (PDV), were observed to be approximately 800 m/s. All the welded samples were subjected to instrumented Peel Testing, microhardness Testing, energy-dispersive x-ray spectroscopy (EDS), and SEM. The welded joints had cracks which ran through the continuous intermetallic layers and stopped upon encountering a ductile metallic wave. The welds created with T6 temper flyer sheets were found to have smaller regions with wavy interfaces free of intermetallics as compared to those created with T4 temper flyer sheets. Peel strength tests of the two types of welds resulted in failure along the interface in case of the T6 flyer welds, while the failure generally occurred in the parent aluminum in the case of the T4 flyer welds. Half of the T4 flyer welds were subjected to aging for 18 hours at 160 °C to convert the aluminum sheet back to T6 condition. Although the flyer material did not attain the hardness of the original T6 material, it was found to be significantly stronger than the T4 material. These welds retained their strengths after the aging process and diffusion across the interface was insignificant.Copyright © 2014 by ASME
Zeike A. Taylor - One of the best experts on this subject based on the ideXlab platform.
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Controlled Peel Testing of a model tissue for diseased aorta
Journal of Biomechanics, 2016Co-Authors: Christopher Noble, Matt J. Carr??, Nicole Smulders, Steve E. Franklin, Sheila Macneil, Roger Lewis, Zeike A. TaylorAbstract:In this study, we examine the effect of collagenase, elastase and glutaraldehyde treatments on the response of porcine aorta to controlled Peel Testing. Specifically, the effects on the tissue??s resistance to dissection, as quantified by critical energy release rate, are investigated. We further explore the utility of these treatments in creating model tissues whose properties emulate those of certain diseased tissues. Such model tissues would find application in, for example, development and physical Testing of new endovascular devices. Controlled Peel Testing of fresh and treated aortic specimens was performed with a tensile Testing apparatus. The resulting reaction force profiles and critical energy release rates were compared across sample classes. It was found that collagenase digestion significantly decreases resistance to Peeling, elastase digestion has almost no effect, and glutaraldehyde significantly increases resistance. The implications of these findings for understanding mechanisms of disease-associated biomechanical changes, and for the creation of model tissues that emulate these changes are explored.
Ulrich Eitne - One of the best experts on this subject based on the ideXlab platform.
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the mechanical theory behind the Peel test
Energy Procedia, 2014Co-Authors: Ulrich Eitne, Li C RendleAbstract:Abstract The Peel test is a very simple and fast method to determine the adhesion of interconnector ribbons to solar cell metallizations. It is part of the solar cell standard DIN EN 50461 and is, due to its ease of use, widely accepted to qualify cell metallizations and the soldering process. In the standard a force of 1 N per mm of joint width is specified but other relevant quantities are missing, for example the Peeling angle. We show that this lack of specification enables the manipulation of Peel Testing results. We therefore apply the mechanical theory of Kinloch [1] where measured Peel forces are translated into adhesive fracture energies GA. The fracture energy is a geometry-independent parameter that describes the energy to break the interfacial bondings at the Peel front. It incorporates the dimensions of the ribbon and its stress-strain-curve. We perform 86 Peel experiments at 90°, 135° and 180° of ribbons on continuous front side busbars of cells from one stringing batch. While the median forces for 90°(3.07 N), 135°(2.35 N) and 180°(3.39 N) differ by up to 30.4% we find the median adhesive fracture energies to deviate by only 17.4%. Using the same adhesive fracture energy (260 J/m2) for a 45° Peel test we expect Peel forces of 7.45 N which is factor 2.4 (2.2) higher than the 90° (180°) Peel forces.
Alin Cristian Chipara - One of the best experts on this subject based on the ideXlab platform.
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underwater adhesive using solid liquid polymer mixes
Materials Today Chemistry, 2018Co-Authors: Alin Cristian Chipara, Thierry Tsafack, Peter Samora Owuor, Jejoon Yeon, Chad E Junkermeier, A C T Van Duin, Somnath Bhowmick, S Syed A AsifAbstract:Abstract Instantaneous adhesion between different materials is a requirement for several applications ranging from electronics to biomedicine. Approaches such as surface patterning, chemical cross-linking, surface modification, and chemical synthesis have been adopted to generate temporary adhesion between various materials and surfaces. Because of the lack of curing times, temporary adhesives are instantaneous, a useful property for specific applications that need quick bonding. However, to this day, temporary adhesives have been mainly demonstrated under dry conditions and do not work well in submerged or humid environments. Furthermore, most rely on chemical bonds resulting from strong interactions with the substrate such as acrylate based. This work demonstrates the synthesis of a universal amphibious adhesive solely by combining solid polytetrafluoroethylene (PTFE) and liquid polydimethylsiloxane (PDMS) polymers. While the dipole-dipole interactions are induced by a large electronegativity difference between fluorine atoms in PTFE and hydrogen atoms in PDMS, strong surface wetting allows the proposed adhesive to fully coat both substrates and PTFE particles, thereby maximizing the interfacial chemistry. The two-phase solid–liquid polymer system displays adhesive characteristics applicable both in air and water, and enables joining of a wide range of similar and dissimilar materials (glasses, metals, ceramics, papers, and biomaterials). The adhesive exhibits excellent mechanical properties for the joints between various surfaces as observed in lap shear Testing, T-Peel Testing, and tensile Testing. The proposed biocompatible adhesive can also be reused multiple times in different dry and wet environments. Additionally, we have developed a new reactive force field parameterization and used it in our molecular dynamics simulations to validate the adhesive nature of the mixed polymer system with different surfaces. This simple amphibious adhesive could meet the need for a universal glue that performs well with a number of materials for a wide range of conditions.