Caustics investigation of interfacial fracture in orthotropic/isotropic bi-material system

Abstract

The crack tip stress intensity factor in a homogeneous isotropic material was easily experimentally evaluated via the caustics method. With respect to the bi-material orthotropic/isotropic system, it is not possible to directly evaluate the interfacial crack stress intensity factor via traditional caustics theory. In the study, theoretical caustics and initial curves at interfacial cracks of orthotropic/isotropic bi-material system were simulated based on caustics parametric equations surrounding the interfacial crack tip derived via the principle of the transmission caustics. To verify the theoretical caustics equation, a dynamic caustics experiment and FEM method under an impact load with the orthotropic/isotropic bi-material system were conducted. The KID evaluated by the dynamic caustics equation agreed well with the FEM results. The results provide an integrated theoretical foundation with respect to the application of the caustics equation on the bi-material interfacial crack problem.