LAUSR

Abstract The Mohr failure criterion has been re-examined and re-presented in a rational manner in the context of brittle materials. The generic assumptions and their logical inferences have been elaborated, as well as the basic assumption of the isotropy of the material. It has been revealed for the first time that the assumption that ‘failure is determined by the stresses exposed on the fracture plane’ relies on the basic assumption of isotropy and its adoption in the establishment of popular modern failure criteria for anisotropic composites is therefore deemed to be out of context. Based on the generic assumptions and well-established experimental observations on the fracture of brittle materials under uniaxial tension, pure shear and uniaxial compression and through rational reasoning, the characteristics of the failure envelope on the tensile side have been deduced, revealing many features which have never been fully established previously. From the perspective of the Mohr criterion, the Coulomb-Mohr criterion has been given a thorough and objective appraisal, leading to a complete dismissal of it as a criterion of practical relevance.