Extension of von-Mises failure criterion for comprehensive mixed-mode I/II fracture assessment of orthotropic materials

Abstract

This study aims to propose a general fracture criterion for cracked orthotropic materials that incorporates normal and shear modes of fracture. For this purpose, an extension of the von-Mises failure criterion, commonly applied to isotropic materials, is utilized to analyze the fracture behavior of orthotropic materials within the linear elastic fracture mechanics (LEFM) framework. The new failure criterion presented in this research is called the extended von-Mises criterion (EVM). The presented criterion is promoted in conjunction with reinforced isotropic solid (RIS) concept which is an efficient material model suitable for orthotropic materials. Thus, the role of the fibers in strengthening the matrix is considered as coefficients in the isotropic stress field of the matrix. This combination is able to properly account for the reinforcing effects of the fibers and the anisotropic mechanical properties of the materials and improve the accuracy of failure predictions. EVM criterion is presented for two different crack propagation scenarios: along and perpendicular to the fibers. In the latter case, kinked crack phenomenon is considered involving crack rotation along the fiber direction, upon encountering the fibers. To investigate EVM accuracy and applicability, this criterion is examined for some wooden species. The fracture limit curves of EVM show promising results when compared to experimental data, indicating that the proposed criterion can accurately predict the failure behavior of materials. It demonstrates performance comparable to the energy-based criterion. The application of RIS theory to enhance this criterion led to a notable increase in its predictive accuracy, suggesting a deeper understanding of the material’s behavior. This enhancement improved performance by 17–20%, and the analysis of the results was conducted with greater precision.