Nonlinear micro-mechanical response of the fibre-reinforced polymer composites including matrix damage and fibre-matrix decohesion

A three-dimensional multi-scale computational homogenisation framework was developed for the prediction of nonlinear micro-mechanical response of the fibre-reinforced polymer (FRP) composite. Two dominant dam- age mechanisms, i.e. matrix damage and fibre-matrix decohesion were considered and modelled using a non- associative pressure dependent thermodynamically consistent paraboloidal yield criterion and cohesive elements respectively. A linear-elastic transversely isotropic materials model was used to model yarns within the representative volume element (RVE), the principal directions for which were calculated using a potential flow analysis along these yarns. A unified approach was used to impose the RVE boundary conditions, which allows conve- nient switching between linear displacement, uniform traction and periodic boundary conditions. Furthermore, the flexibility of hierarchic basis functions and distributed memory parallel programming were fully utilised. The accuracy and performance of the developed computational framework were demonstrated using an RVE with ran- domly distributed but periodic and axially aligned unidirectional fibres subjected to transverse tension and shear. The macro-strain versus homogenised stress responses were validated against the reference results from the liter- ature. Finally, effects of varying interfacial strength and fracture energy were studied on the homogenised stress versus macro-strain responses.