A New Welding Process Simulation Using a Hybrid Particle and Grid Method with Explicit MPS

Abstract

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. 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. However, particle methods such as smoothed-particle hydrodynamics (SPH) [1] or the moving particle semi-implicit (MPS) method [2], which represents the fluid flow as moving particles, can more easily evaluate the fluid flow and thermal conduction with a free surface than grid methods. However, particle methods generally need to simulate equal particle sizes. This means that the calculation cost using particle methods is larger than that using grid methods. Therefore, an analysis using the particle method is effective for the weld pool, but not for the full-size weld joint. In the present study, first, for high-speed, effective simulation of the welding process, including the weld pool, explicit MPS [3, 4] is performed. Second, a hybrid particle and grid method [5] is used for welding process simulation. In the 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 add the interface effects, which are caused by the arc pressure and the heat input, a light source model for the welding process simulation is developed. The model can consider the radiated effects of the heat source. As a result, numerical simulation of the heat conduction in the weld joint, including the fluid flow in the weld pool, is performed.