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 of overcoming the volumetric locking problem in 2D and 3D solid elements. This method of finite elastoviscoplasticity is discussed as are its well-known limitations. In this context, an isochoric-volumetric decoupled material behavior is assumed and thus 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 behaviour. The application of this process to so-called solid-shell elements for thin-walled structures is also discussed.