An Explicit Time Scheme With Local Time Stepping for One-Dimensional Wave and Impact Problems in Layered and Functionally Graded Materials

Abstract

Abstract. The standard explicit time scheme (e.g. the central difference method) in finite element analysis is not able to keep accuracy of stress distribution through meshes with different local Courant numbers for each finite element. Therefore in this paper, we suggest and test a two-time step explicit scheme with local time stepping for direct time integration in finite element analysis of wave propagation in heterogeneous solids. The nominated two-time step scheme with the diagonal mass matrix is based on the modification of the central difference method with pullback interpolation and local time stepping. It means that we integrate stress situation on each finite element with local stable time step size. With local time stepping, it is possible to track more accurately a movement of wavefronts for finite element meshes with different local Courant numbers. We present numerical examples of one-dimensional wave propagation in layered and graded elastic bars under shock loading. Based on numerical tests, the presented time scheme is able to eliminate spurious oscillations in stress distribution in numerical modelling of shock wave propagation in heterogeneous materials.