Recent Advances and New Developments in Hot Forming Simulation with LS-DYNA

The analysis and optimization of hotforming processes necessitates the use of thermal-mechanical coupled finite element simulations. One of the key issues in process simulation is the choice of an appropriate modelling approach for the tools. Splitting the process into the two fundamental partial stages forming and cooling is an efficient way to set up a simulation model. The forming stage needs the tool surface discretized with a rather fine shell mesh to meet typical geometric accuracy requirements. The quenching stage furthermore requires a 3-dimensional volume mesh to account for the heat dissipation into the tools. Model size and meshing effort both can be considerably reduced if the volume mesh is generated independently of the geometric accuracy requirements for the surface representation. Thermal contact options in LS-DYNA are then used to connect the fine surface shell mesh and the volume mesh to enable an accurate prediction of the contact situation and moreover the calculations of the 3-dimensional heat flow into the tool. A recent development is a simplified 1D-fluid flow calculation in the thermal solver to consider cooling passages in the tools. This feature enables thermal tool analysis after a sequence of several production cycles.