Numerical damping of spurious oscillations: a comparison between the bulk viscosity method and the explicit dissipative Tchamwa-Wielgosz scheme

The use of Finite Element and Finite Difference methods of spatial and temporal discretization for solving structural dynamics problems gives rise to purely numerical errors. Among the many numerical methods used to damp out the spurious oscillations occurring in the high frequency domain, it is proposed here to analyse and compare the Bulk Viscosity method, which involves calculating the stresses, and a method recently presented by Tchamwa and Wielgosz, which is based on an explicit time integration algorithm. The 1-D study and the 2-D axisymmetric study on a bar sub- jected to compression and impact loads presented here show that the former method is insensitive to meshing irregular- ities, whereas the latter method is not. The Bulk Viscosity method was found to be sensitive, however, to the behavior of the material, contrary to the Tchamwa-Wielgosz method. Since comparisons of this kind are rather complex, a specific method of analysis was developed.