Volume and shape
The hydrostatic part of a strain changes volume and leaves the shape. The deviator changes the shape and leaves the volume. The same split on stress is the path to von Mises: metals yield on the deviator.
ε = (tr ε / 3) I + ε′
The hydrostatic part of a strain changes volume and leaves the shape. The deviator changes the shape and leaves the volume. The same split on stress is the path to von Mises: metals yield on the deviator.
ε = (tr ε / 3) I + ε′