Finite element modeling of laser beam welding for residual stress calculation

Abstract

Numerous welding processes are used in naval, automotive and aircraft industries for joining structural components. Laser beam welding represents a key technology due to his low heat input and the high degree of process automation. Nonetheless, all welded materials are characterised by a strong change of microstructure in the heat effected and fusion zone. For simulation of residual stress fields the finite element method is the most often simulation tool. Reliable simulations have to take into account the changes in microstructure. Within this work, a viscoplastic material model for welding is presented, accounting for the solid and fluid phase, which is extended later on by a simple kinetic model to model precipitation hardening.

Multiscale process simulation of residual stress fields of laser beam welded precipitation hardened AA6082

“…The fully implicit elastic return-mapping algorithm with nonlinear isotropic hardening for the material has been outlined by Herrnring and Klusemann (2017) and summarized in Algorithm 2 for completeness. Due to the incompressible material behaviour in the liquid case, a mixed u/p-finite-element formulation is used.…”

“…Algorithm 2 Integration of elasto-visco-plastic material model for welding processes over time interval [t n , t n+1 ]. Extended algorithm based on Herrnring and Klusemann (2017). The step at t n with strains {ε n , ε p n , ε p n } and the strain increment ∆ε are given.…”