A damage model with non-convex free energy for quasi-brittle materials

TL;DR

This paper introduces a damage model with non-convex free energy incorporating hydrostatic and deviatoric coupling, effectively capturing concrete's dilatancy and localization behavior under various loading conditions.

Contribution

It presents a novel damage model with state coupling between volumetric and deviatoric energy parts, validated through experiments and suitable for finite element implementation.

Findings

Describes large dilatancy of concrete under compression.

Captures different damage levels in tension and compression.

Validated on bi-compression and bi-tension tests.

Abstract

A state coupling between the hydrostatic (volumetric) and deviatoric parts of the free energy is introduced in a damage mechanics model relevant for the quasi-brittle materials. It is shown that it describes the large dilatancy of concrete under compression and the different localization angles and damage levels in tension and compression. A simple isotropic description is used, although similar ideas can be extended to anisotropic damage. The model is identified with respect to tensile and compression tests and validated on bi-compression and bi-tension. Fully written in three dimensions under the framework of thermodynamics of irreversible processes, it allows further developments within a finite element code.