Mohr-Coulomb criterion with circular failure envelope, extended to materials with strength-differential effect.

The linear Mohr–Coulomb (M-C) failure criterion is widely used to describe the behaviour of materials with compression/tension asymmetry, such as geological materials. Difference in compressive and tensile fracture/yielding stress is so-called strength difference or SD effect. A modified M-C criterion was proposed previously to describe the failure of ductile materials and to better fit the experimental data [ 1 ]. A circular failure envelope, tangent to the Mohr's circles corresponding to the limit state of stress for uniaxial tension, compression and pure shear, was considered. In this paper, the above circular M-C criterion is extended to brittle materials (with SD effect). The new criterion has been compared with fundamental criteria in plasticity theory and experimental results taken from literature. In the space σ 1 -σ 3 it is represented by two segments of hyperbola and allows a smooth transition from linear M-C to Rankine criteria. It proves to be adaptable to a wide range of materials and this is a major advantage. Moreover, the paper demonstrates also that all yield criteria for standard plastic materials, without SD effect, under biaxial state of stress, are insensitive to hydrostatic pressure. [ABSTRACT FROM AUTHOR]