Anisotropic microcrack-based frictional damage model for brittle materials

An anisotropic constitutive model based on the assumption of linear elastic matrix weakened by microcraks is derived by assuming a tensorial description of the damage and of the unilateral andfrictional effects on the displacement jump across the crack faces. Damage and sliding evolutions are obtained by defining proper limit conditions and associated flow rules. This treatment implies a different tensile-compressive response because under triaxial tensile stress states only the damage limit condition is effective, otherwise this condition must be coupled with the frictional sliding one. By considering monotonic loading paths, the constitutive equations provide limit strength domains; limit domains for the case of biaxial stress states are obtained and their dependence on the friction coefficient is shown