Hierarchical multi-scale modelling of flax fibre/epoxy composite by means of general anisotropic viscoelastic-viscoplastic constitutive models: Part I - Micromechanical model

A main problem for the development of comprehensive continuum mechanical models is the lack of experimental data. To overcome this problem, a non-associative viscoelastic-viscoplastic constitutive model which takes into account combined isotropic-kinematic hardening effects for epoxy matrix as well as a three dimensional non-associative anisotropic nonlinear elastic/plastic constitutive model for flax fibre is developed. The constitutive models are assigned to a representative volume element (RVE) of a unidirectional flax fibre/epoxy composite. Upon application of periodic boundary conditions (PBCs), different loading scenarios are subjected to the RVE and the mechanical response of the composite is studied. Based on the performed micromechanical analyses, a continuum model is developed for the unidirectional flax fibre/epoxy composite in Part II of this paper. (C) 2020 Elsevier Ltd. All rights reserved.