During welding, the weld pool has a fluid flow with thermal conduction and a free surface. The dropped metal also supplies a free surface. These complex phenomena are difficult to simulate using the grid method. On the other hand, particle methods, such as the smoothed-particle hydrodynamics (SPH) method or the moving particle semi-implicit (MPS) method, can evaluate the fluid flow and the thermal conduction with a free surface more easily than grid methods. In the present study, for high-speed and effective simulation of the welding process, including the weld pool, a hybrid particle and grid method with explicit MPS is performed. In this hybrid method, particles can be used in the weld pool and the area located near the weld pool, whereas grid elements are used in the other areas. Furthermore, in order to consider interface effects, a light source model for the welding process simulation is developed. As a result, numerical simulation of the heat conduction in the weld joint, including the fluid flow in the weld pool with a free surface, is performed.

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SAW 12 13) [ 28 p. 158-166 (2010)]

Al-Mg alloy sheets often exhibit surface defects, e.g., stretcher strain, after sheet metal forming. The surface defects are formed by nonuniform deformation due to the dynamic strain aging where serrations appear on stress-strain curves in tensile test. In order to suppress the nonuniform deformation, the authors propose periodic micro indentation on sheet surface in this study. Four Al-Mg alloy sheets were subjected to the tensile test after the indentation. Strain gauges on specimen surface were used to investigate the evolution of local strain. It is concluded that the periodic indentation can suppress nonuniform deformation.