On Volumetric Locking of Low-order Solid and Solid-Shell Elements for Finite Elastoviscoplastic Deformations and Selective Reduced Integration

As known from nearly incompressible elasticity selective reduced integration (SRI) is a simple and effective method to overcome the volumetric locking problem in 2D and 3D solid elements. The aim of this contribution is to discuss this method for finite deformation elastoviscoplasticity, though it is well known that there are limits, which will be investigated in more detail. In this context an isochoric-volumetric decoupled material behavior is assumed and then the additive deviatoric-volumetric decoupling of the consistent algorithmic moduli tensor is essential. By means of several numerical examples the performance of elements using selective reduced integration is demonstrated and compared to the performance of other elements such as the enhanced assumed strain elements. It is shown, that a minor modification with little numerical effort leads to rather robust element behavior. A further focus is on the application of this concept to so-called solid-shell elements for thin-walled structures.