A FDM-based experimental benchmark for evaluating quasistatic crack propagation in anisotropic linear elastic materials

Anisotropic materials gain importance in industry pushed forward by new applications, from wood construction, single crystals for photovoltaic applications or aerospace turbines, to Additive Manufactured materials. But due to the lack of certified damage tolerance models to guarantee their resistance to failure, their use in aerospace or nuclear sensitive components whose failure must be avoided at all costs is limited. In this context, we present herein a new experimental benchmark, instrumented by Digital Image Correlation, aiming to test quasistatic crack propagation models for anisotropic linear elastic materials, for instance phase field variational approaches. The benchmark is based on Compact Tensile and Compact Tensile Shear samples printed by Fused Deposit Modeling of polycarbonate threads. The flexibility of the printing process is used to produce specimens that exhibit directional dependence of the fracture toughness. Fracture experiments with these samples have been designed to enter in the framework of two-dimensional (2D) Linear Elasticity Fracture Mechanics (LEFM) with strong fracture anisotropy, while avoiding additional complexities by preserving isotropic elasticity and quasistatic propagation. Close comparisons with the experiments demonstrate that the generalized maximum energy release rate criterion accurately predicts crack propagation. While serving as a benchmark, these experiments also lay the foundation for a better fundamental understanding of crack propagation in anisotropic materials, beyond FDM printed parts.