Behavior of cracked materials

TL;DR

This paper develops a thermodynamics-based micromechanical model to describe the behavior of rough cracks in quasi-brittle materials, accounting for interlocking, friction, and cohesion effects.

Contribution

It introduces a novel model combining irreversible thermodynamics and structured deformation theory to analyze crack roughness and sliding effects.

Findings

Crack opening depends on shape and sliding

Yield surface incorporates Coulomb friction and cohesion

Model applies to tension and compression cases

Abstract

Due to their microstructure, quasi brittle materials present rough cracks. Under sliding of the crack lips, this roughness involves in one hand induced opening and in the other hand some apparent plasticity which is due to the interlocking of the crack lips combined with Coulomb's friction. The proposed model is written under the irreversible thermodynamics framework. Micromechanics uses the Del Piero and Owen's structured deformation theory. Opening of the crack depends upon the crack shape and the relative sliding of the crack lips. The thermodynamic force associated to the sliding has the mechanical meaning of the force acting in order to make the crack slide. Yield surface is defined as a limitation of this force with respect to the Coulomb's friction and the Barenblatt cohesion. The crack orientation is defined as the one for which the criterion is reached for the lowest stress level. A decreasing cohesion, respect to sliding is supposed. Tension and compression reference cases are envisaged.