The characteristic width assignment method for anisotropy-interface phase field model: Proposed and validation

This study addresses the complex mechanical behavior of interface debonding in anisotropic materials by proposing a novel phase field model that integrates cohesive zone model with anisotropy theory. The core innovation lies in developing a characteristic width allocation strategy based on interface softening laws. By establishing a functional relationship between characteristic width and interfacial mechanical strength, this model overcomes the limitations of characteristic width selection in conventional phase field methods, enabling precise characterization of interfacial mechanical properties. Experimental validation demonstrates that the phase field simulation results using the proposed characteristic width optimization criteria exhibit excellent agreement with bimaterial plate tensile experiments. In single circular reinforced concrete tensile simulations, the model achieves results consistent with theoretical solutions (${\alpha }_{\mathrm{kink}}=68.8829°$) and exceeds the accuracy of the extended finite element method by approximately $4.3\%$. The numerical predictions of mechanical behavior in anisotropic multiphase materials align with physical expectations. This approach elucidates interface damage evolution mechanisms under varying softening laws and matrix anisotropy characteristics, providing a high-precision computational framework for interfacial failure analysis in anisotropic multiphase materials.