Compact tension specimen for orthotropic materials

A solution for a Compact Tension (CT) specimen is proposed in order to obtain the linear elastic fracture toughness, the stress intensity factor and the compliance at the load line. The solution applies for any orthotropic material whose principal directions are defined by the crack direction, assuming that the crack grows along the symmetry plane of the specimen. Given two dimensionless parameters, λ and ρ, that define the orthotropy of the material, the elastic response is unique. With the aid of a parameterized Finite Element Model (FEM), a solution is obtained for any orthotropic material. The results are fitted into an interpolating function, which shows excellent agreement with simulated data. Additionally, the initial crack length required to produce a stable crack growth under displacement control is studied for various material orthotropies. Finally, some failure criteria are introduced regarding the failure at the holes of the CT and at the back end face of the specimen. Some design recommendations are given after analyzing the failure mechanisms.