Numerical simulation of dynamic weld compression

The article presents some numerical results and experimental validation of Split Hopkinson pressure bar (SHPB) tests for welded S40NL steel. The goal of this research is to define material constants for modelling it in FEM. Steel was tested with Charpy impact test to determine properties of material. Next, the joint for welding was prepared. It was welded with electric arc welding method (MAG) with flux-cored wire. Hopkinson bar test is well-known experiment method used to determine material properties at high strain rates. The tests were performed in Institute of Fundamental Technological Research. Material properties for Johnson-Cook material model were obtained. Comparison between experimental results taken in quasi-static conditions and dynamic conditions proves that the behaviour of materials in those two states is quite different. Results from one type of loading condition cannot be used to create a realistic model of material when it is loaded dynamically. Numerical simulation of Hopkinson bars was performed on cylindrical model with known length and accelerated to high speed in direction of incident bar. For the purpose of the simulation, a Finite Element Code LS-DYNA was used. It allows simulation of dynamic response of SHPB system. The results show quite good agreement. The model can be used to simulate weld performance under high strain rate.