Isotropic Softening Material
Constitutive Law
This MPM Material is an isotropic, elastic material, but once it fails, it develops anisotropic damage. The constitutive law for this material is
[math]\displaystyle{ \mathbf{\sigma} = (\mathbf{I} - \mathbf{D}) \mathbf{C} \mathbf{\varepsilon} }[/math]
where [math]\displaystyle{ \mathbf{C} }[/math] is stiffness tensor for the underlying isotropic material and [math]\displaystyle{ \mathbf{D} }[/math] is an anisotropic 4th rank damage tensor.