Modified nonlinear Mohr-Coulomb fracture criteria for isotropic materials and transversely isotropic UD composites

Modified nonlinear Mohr-Coulomb (M-C) fracture criteria for isotropic materials and transversely isotropic unidirectional (UD) composites are proposed in the present study. The classic linear M-C fracture criterion for isotropic materials is briefly revised, and its deficiencies and limitations are identified. Based on the modification of a nonlinear variation of the M-C criterion for UD composites, the mathematical expressions of the proposed fracture criteria are formulated. The undetermined parameters in the expressions are calibrated by the experimental data from the simple tension, compression and shear tests. The presented fracture criteria show good agreement with the test data of various kinds of isotropic materials and transversely isotropic UD composites under different stress states.