• Proceedings of the KWS Conference
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• 1999.05a
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• pp.233-236
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• 1999

The welding residual stress should be considered in fatigue stress analysis because it develope during the process of the electric resistance spot welding and it causes bad affect on the fatigue crack initiation and growth at nugget edge of spot welded points. Therefore the accurate estimation of residual stress is crucial. In this study, nonlinear finite element analysis on welding residual stress generated during the process of the spot welding was conducted, and their results were compared with the experimental data measured by X-ray diffraction method. From the results, it was found that welding residual stress existed as tension in the nugget center and as compression around the nugget edge.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.3 s.174
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• pp.743-751
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• 2000

Because welding residual stress is formidable result in electric resistance spot welding process, and it detrimentally affect to fatigue crack initiation and growth at nugget edge of spot welded la p joints, it should be considered in fatigue analysis. Thus, accurate prediction of residual stress is very important. In this study, nonlinear finite element analysis on welding residual stress generated in process of the spot welding was conducted, and their results were compared with experimental data measured by X-ray diffraction method. By using their results, the maximum principal stress considered welding residual stress at nugget edge of the spot welded lap joint subjected to tension-shear load was calculated by superposition method. And, the $\Delta$P- $N_f$ relations obtained through fatigue, tests on the IB-type spot welded lap joints was systematically rearranged with the maximum principal stress considered welding residual stress. From the results, it was found th2at fatigue strength of the IB-type spot welded lap joints could be systematically and more reasonably rearranged by the maximum principal stress($\sigma$1max-res considered welding residual stress at nugget edge of the spot welding point.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.395-398
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• 2006

Forging is applied for many industrial fields. Also, it is applied to hose nipple. Stress and metal analysis is finding method of forging possibility and we predict this possibility by finite element forging analysis. But there are also many manufacturing procedure after forging, and metal texture is varied by additional heat treatment or coating. So this research is focused on the measuring and analysis of plastic residual stress distribution at overall manufacturing procedure. From raw material to final product we measured real residual stress at each manufacturing procedure by X ray diffract meter, and simulated another procedure except forging by nonlinear finite element analysis. Also we showed how Zn-Ni coating is more contributable to metal strength than Zn coating. By this research we make final conclusion that process analysis must be observed from raw material to final manufacturing state for robust design.