Investigating interfacial cracks in bi-materials through a 4-point bending model analysis

This study focuses on examining the failure behavior of interfacial cracks in bimaterial structures. Bimaterials present a unique challenge due to their composition, consisting of two materials that can be homogeneous and isotropic, with a specific emphasis on the ceramics/metal combination. The disparity in elastic and physical properties between these materials leads to stress singularities and embrittlement of the interface. In order to investigate the behavior of an interfacial crack without propagating into the individual materials, numerical simulations of a 4-point bending model were conducted. The stress intensity factors were computed at the crack tip to determine the energy release rate, which is a crucial parameter in evaluating interfacial crack behavior. The energy release rate, along with the mixed mode angle ($G$, $\psi$), provides insights into the crack's response. The findings demonstrate that an increase in the thickness ratio ($H_1/H_2$) of the assembled materials, as well as a reduction in the Young's modulus ratio ($E_1/E_2$), result in higher energy release rates for interfacial cracks in bimaterials. This indicates that the properties of the assembled materials play a significant role in determining the dominant mode of crack propagation tendency.