Non-linear elastic tension-compression asymmetric anisotropic model for fibre-reinforced materials

We present a novel constitutive model capable of describing non-linear anisotropic fibre -reinforced materials with different responses in tension and compression under a general stress state. The model is based on the original one-dimensional Ramberg-Osgood model, which is generalized to a multiaxial stress state and anisotropic material behaviour under thermodynamic requirements. To account for tension-compression asymmetry under a multiaxial stress state, the model is extended by the use of the stress triaxiality invariant as an indicator of stress state type, e.g. shear, uniaxial or biaxial tension, compression, etc. The model is implemented in ABAQUS/Explicit via the VUMAT subroutine and verified on two material datasets, which are an S2-glass/E773-epoxy and a reinforced polyester composite material. In comparison with other models, the proposed model provides an elegant formulation for the description of all the aforementioned phenomena, resulting in a simple calibration procedure based on uniaxial tensile and compressive tests.