Modelling and simulation of simultaneous forming and quenching

Abstract: The objective of this thesis is to develop and evaluate numerical methods for modelling and simulation of simultaneous forming and quenching within an integrated product development environment. Simultaneous forming and quenching, also referred to as hot-stamping, is a manufacturing process for high strength automotive components such as side impact protection beams. A concept for integrated product and process development is proposed. The prototype system consists of a CAD system, a relational database management system, program interfaces, and nonlinear finite element programs. A thermal model based on explicit time integration is developed and implemented into the explicit finite element code DYNA3D to solve coupled thermomechanical problems. The implementation includes a linear-quadratic thermal shell element, and contact heat transfer. The material behaviour is described by a thermo-elastic-plastic material model. The effective-stress-function algorithm is used to update the stresses. The implemented methods are evaluated by comparison with corresponding experimental results. In one of the developed experiments, pre-heated steel plates are simultaneously formed and quenched by a cold tool. The analyses show good agreement during the initial stage, followed by an overestimation of the tool force at sequential times. It is shown that the computed tool force is very sensitive to the sequence of cooling in different parts of the plate.