Development of a non-orthogonal macroscale material model for advanced woven fabrics based on mesoscale structure

A macroscale non-orthogonal constitutive material model for woven fabrics based on a mesoscale unit cell is developed and implemented in an explicit finite element code. The model utilizes two important deformation mechanisms involved in woven fabrics: (1) Yarn elongation, and (2) Relative yarn rotation due to shear loads. The yarns' uniaxial tensile response is modeled using nonlinear springs within the unit cell formulation while a nonlinear rotational spring is used to define the fabric's shear stiffness. Continuum mechanics are employed to keep track of the yarn orientations at a given unit cell configuration. Material properties/parameters of the model can be easily determined from standard experimental tests. The material model is validated using uniaxial tensile, bias extension, 30° off axis tension and indentation tests for two different plain weave Kevlar fabrics. The results show that the developed model is capable of the mechanical response of the woven fabrics under various loading conditions.