Damage of short-fibre reinforced materials with anisotropy induced by complex fibres orientations

• We model the elastoplastic damage behaviour of short-fibre-reinforced composites.
• The composite behaviour is computed without any complex procedure of homogenisation.
• Complex short-fibres distributions of orientation are modelled in a simple way.
• The damage anisotropy of the matrix material is governed by the reinforcement.
• A progressive degradation of the fibre–matrix interfaces is modelled.

In this paper, a behaviour model for damageable elastoplastic materials reinforced with short fibres that have complex orientations is proposed. The composite material is seen as the assembly of the matrix medium and several linear elastic fibre media. Its macroscopic behaviour is computed thanks to an additive decomposition of the state potential, with no need to implement complex methods of homogenisation. A 4th-order tensor that depends on the characteristics of each fibre medium is introduced to model the anisotropic damage of the matrix material induced by the reinforcement, as well as the progressive degradation of the fibre–matrix interface. The division of short fibres into several families means that complex distributions of orientation or random orientation can be easily modelled. The model is tested for the case of a polyamide reinforced with different contents of short-glass fibres with distributed orientations and subjected to uniaxial tensile tests in different loading directions. The comparison of the results with experimental data (extracted from the literature) demonstrates the efficiency of the model.