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.

开发综合连续力学模型的主要问题是缺乏实验数据。为了克服这个问题，开发了一种非缔合的粘弹性-粘塑性本构模型，该模型考虑了对环氧树脂基体的各向同性的运动硬化效应，以及三维三维的非缔合各向异性的非线性弹性/塑性本构模型。本构模型分配给单向亚麻纤维/环氧树脂复合材料的代表性体积元素（RVE）。在应用周期性边界条件（PBC）的情况下，对不同的载荷情况进行RVE分析，并研究了复合材料的机械响应。根据执行的微力学分析，