Numerical studies on laser impact welding: Smooth particle hydrodynamics (SPH), Eulerian, and SPH-Lagrange

Abstract

Smooth particle hydrodynamics (SPH) and Eulerian methods are widely used in the numerical simulation of laser impact welding (LIW). However, SPH method cannot directly apply pressure load generated by plasma and can only realize the loading effect of the plasma pressure load by presetting the shape and initial velocity of the flyer plate. However, the welding interface waveform and jet phenomenon produced by the Eulerian method due to the regular material mixing mode is not as clear as that by the SPH method. In addition, it cannot effectively show the central springback and cracking in the LIW. A new numerical simulation method for LIW, namely, smooth particle hydrodynamics and Lagrange coupling method (SPH-Lagrange). The idea is to couple the Lagrange grid and SPH particles on the flyer model, which can apply the impact load generated by the plasma on the upper surface of the flyer model; as a result, the loading conditions are in line with reality. The simulation results of local velocity, shear stress, equivalent plastic strain, and temperature state of the welding interface obtained by the SPH, Eulerian, and SPH-Lagrange methods were compared and studied. The interface waveforms obtained by different laser energies were compared with the simulation results of the SPH-Lagrange method. The numerical simulation calculations show that the SPH-Lagrange method is more consistent with the LIW experiment. Compared with other methods, SPH-Lagrange method is more suitable for the simulation of the LIW combination process and interface characteristics. Finally, the possible existence of melting phenomenon in LIW process was investigated using the SPH-Lagrange method.