Development and simulation of invariant-based plasticity models for a carbon epoxy composite

The thesis consisted in the development of two transversely-isotropic elastic–plastic constitutive models for unidirectional fiber reinforced polymers. Both these models are able to represent the fully non-linear behaviour under multi-axial loading conditions. Moreover, an anisotropic pressure-dependant yield function and a non-associated plastic potential function, are assumed in order to model realistic plastic deformations. The models were then implemented in the commercial finite element software ABAQUS/Implicit, for which two UMAT (user defined material subroutines) in FORTRAN had been developed