• Journal of Welding and Joining
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• v.29 no.5
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• pp.47-53
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• 2011

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.253-255
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• 2006

Grey relational analysis has been carried out to develop a new approach for optimization of Nd:YAG laser and MIG hybrid welding parameters. The quality of welded material depends on welding parameters. The parameters chosen for current study include wire type, shielding gas, laser energy, laser focus, traveling speed, and wire feed rate. The welding experiments were performed on 6K21-T4 aluminum alloy sheet. Functional demands on products may vary widely depending on their use. The ultimate tensile stress, width, and penetration were chosen as the optimization criterion. Practice based on an orthogonal array which is following Taguchi's method has been progressed. Base on the results of grey relational analysis, the optimal process parameters were obtained. This integrated work was judged and it is observed that the results obtained by using the optimal parameters are much improved compared to those obtained through initial setting.

• Journal of Welding and Joining
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• v.34 no.1
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• pp.59-67
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• 2016

The automotive manufactures increase their use of lightweight materials to improve fuel economy and energy usage has a significant influence on the choice of developing materials. To meet this requirements manufacturers are replacing individual body parts with lightweight metals, for these the process treating and painting surfaces is changing. The pre-coated steels are newly developed to avoid the conventional complex and non-environmental painting process in the body-in-white car manufacturing. The development of new joining techniques is critically needed for pre-coated steel sheets, which are electrically non-conductive materials. In the present study, dissimilar combination of pre-coated steel and galvanized steel sheets were joined by the self-piercing rivet, adhesive bonding and hybrid joining techniques. The tensile shear test and free falling high speed crash test were conducted to evaluate the mechanical properties of the joints. The highest tensile peak load with large deformation was observed for the hybrid joining process which has attained 48% higher than the self-piercing rivet. Moreover, the hybrid and adhesive joints were observed better strain energy compared to self-piercing rivet. The fractography analyses were revealed that the mixed mode of cohesive and interfacial fracture for both the hybrid and adhesive bonding joints.

• Proceedings of KOSOMES biannual meeting
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• 2018.06a
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• pp.166-166
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• 2018

• Journal of Welding and Joining
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• v.24 no.5
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• pp.43-48
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• 2006

This paper is concerned with a fracture strength study of composite adhesive lap joints. The tests were carried out on specimen joints manufactured hybrid stacked composites such as the polyester and bamboo natural fiber layer. The main objective of the work was to test the fracture strength using hybrid stacked composites with a polyester and bamboo natural fiber layer. Tensile and peel strength of hybrid stacked composites are tested before appling adhesive bonding. From results, Natural fiber reinforced composites have lower tensile strength than the original polyester. and The load directional orientation and small amount and low thickness of bamboo natural fiber layer have a good effect on the tensile and peel strength of natural fiber reinforced composites. The failure strength of these materials applied adhesive bonding is also affected by fiber orientation and thickness of bamboo natural fiber layer. There for, Fiber orientation of bamboo natural fiber layer have a great effect on the tensile-shear strength of natural fiber reinforced composites including adhesive bonded joints.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.10
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• pp.901-906
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• 2016

The purpose of this study is to improve productivity by implementing one-pass full penetration welding using laser-arc hybrid welding for AH36. On increasing the thickness of the plate, a higher power of laser and arc was required to obtain full penetration. However, increasing the power of heat source caused undercut defects at both ends of the bead. This undercut was prevented by controlling the parameters of welding voltage and pulse correction. Hardness measurement and tensile test were conducted to apprehend the mechanical properties of weld. Also, by carrying out the microstructure observation for laser and arc regions, microstructural properties were understood.

• Journal of Welding and Joining
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• v.31 no.6
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• pp.107-111
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• 2013

The welding distortion is caused by welding heat in the structures which are widely used in shipbuilding and automotive industries, thus many researchers have proposed such methods to control the welding distortion through trials and numerical studies. The welding distortion has been the main cause of low productivity due to the structural strength degradation, apparent flaw, additional deformation caused by the process followed the current assembly step, and the increase of correction workload. The deformation of fillet welding is investigated in this study, and the influence of the rib height on the welding distortion is verified through the actual experiment. And the numerical analysis model using the FE software MSC.marc for analysis of welding distortion is proposed.

• Journal of Welding and Joining
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• v.33 no.4
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• pp.17-23
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• 2015

Laser-gas metal arc hybrid welding has been considered as an alternative process of gas metal arc welding for offshore pipe laying. Fiber delivered high power lasers which enable deep penetration welding were recently developed but high power welding characteristics were not fully understood yet. In this study, the influence of shielding gas composition on welding phenomena in high power laser welding was investigated. Bead shapes, melt ejection and dropping were observed after autogenous laser welding with 100% Ar, Ar-20% $CO_2$, Ar-50% $CO_2$, and 100% $CO_2$ shielding gas. Process parameter window was widest with Ar-50% $CO_2$ shielding gas and the penetration was deepest with 100% $CO_2$ shielding gas. The melt dropping was not observed when Ar-50% $CO_2$ or 100% $CO_2$ shielding gas was supplied.

• Journal of Welding and Joining
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• v.34 no.4
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• pp.62-66
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• 2016

The trend of the fabrication technology of high strength, high toughness aluminum alloys by the severe plastic deformation(SPD) process and the welding technology of lightweight alloys in the automobile has been studied. The lightweight aluminum alloys can reduce vehicle weight, while stringently demanding the high quality and efficient welding techniques, to produce the best weldments. Among the production technologies, welding plays an important role in the fabrication of lightweight vehicle structure. This paper covers the scientometric analysis of the severe plastic deformations of lightweight alloys and the welding technology in the automobile which are based on the published research works in the 'HPT, ECAP and rolling', and 'welding technology of the automobile' obtained from Web of Science, and deals with the details of the background data of the HPT, ECAP, and rolling of lightweight alloys, and welding technology of the automobile technology.

• Journal of Welding and Joining
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• v.24 no.3
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• pp.55-59
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• 2006

This paper is concerned with a study on cyclic bending load of bus folding door pillar including adhesive bonding and spot welding. Three specimen types were used such as spot welding, I-type adhesive bonding and M-type adhesive bonding in this study. The tensile-shear tests were carried out to evaluate the tensile-shear strength of these three specimen types. Also four-point bending tests were carried out to evaluate the static and dynamic bending load. From the results, using adhesive bonding has a better effect on the static and dynamic bending load than using spot welding. Therefore, manufacturing better structural products can be expected by applying hybrid welding using adhesive and spot welding to those.