Restrictions in phase field modeling of brittle fracture

Abstract

AbstractA key feature of phase field approaches to fracture is the relatively simple structure of the method. However, current approaches inevitably exhibit some limitations which do not seem to be obvious and are therefore neglected in many investigations. The assumption of isotropic stiffness degradation by a scalar phase field parameter does not capture the anisotropy introduced by a crack and severely restricts the scope of application. Widely used tension‐compression splits violate the specific conditions at cracks like traction free crack surfaces and, in addition, introduce mesh orientation dependency. Accurate approximation of the surface (fracture) energy is another important requirement which is discussed for a non‐vanishing internal length ℓ.