Entities: Reduced Integration

Description

For a structure of nearly incompressible material with Poisson's ratio approaching 0.5, the finite element solution can be significantly stiffer than the actual structural behaviour because the chosen shape functions impose spurious constraints to the structural displacements. Under this situation, a reduced integration for the element stiffness matrix can often improve the element's performance and results.

However, reduced integration may cause numerical instability in some situations due to the introduction of spurious zero-strain energy modes such as when the finite element model is not appropriately restrained on the boundary. This means that the element may become singular if reduced integration is used.

Reduced integration in Straus7 is available for:

Quad8 and Quad9 plate elements of 2D Plane Strain, 2D Plane Stress and Axisymmetric analysis types and of Isotropic, Orthotropic, Anisotropic, Laminate or Rubber material.
Hexa16 and Hexa20 brick elements of Isotropic, Orthotropic, Anisotropic or Rubber material.