Damage and failure mechanisms of biaxial weft-knitted reinforced composites via meso-scale finite element modeling

A meso-scale finite element model based on progressive damage was proposed to capture the failure and damage mechanisms of biaxial weft-knitted (BWK) composites. For this purpose, a suitable representative volume element of a BWK composite material was modeled. Then, appropriate boundary conditions were applied to simulate the uniaxial tensile test in the course and wale directions. Damage and failure mechanisms were predicted by developing a VUMAT user material subroutine based on the 3D Hashin criterion. To verify the numerical results, a comparison was made with the experimental data of Hessami et al. ¹ It was found that the failure mechanisms of BWK composite are determined by the geometrical parameters of the BWK fabric. Based on the numerical assessments, some recommendations were made to fully exploit the potential of BWK composites as load-bearing structures. The numerical results provided new insights into the effect of the geometric parameters of BWK preforms on the composite failure mechanisms.