Strain Rate
The relationship between the physical coordinate and computational intrinsic coordinates system for a brick element is given by the matrix equation:
Hence:
Where, is Jacobian matrix.
The element strain rate is defined as:
Relating the element velocity field to its shape function gives:
Hence, the strain rate can be described directly in terms of the shape function:
As was seen in Velocity Strain or Deformation Rate, volumetric strain rate is calculated separately by volume variation.
For one integration point:
F.E Method is used only for deviatoric strain rate calculation in A.L.E and Euler formulation.
Volumetric strain rate is computed separately by transport of density and volume variation.