Mechanical behavior of hybrid biaxial single jersey knitted-reinforced composites: Experimental and numerical approaches

摘要

The biaxial weft-knitted (BWK) preform is a unique category of weft-knitted preforms that combines the ad-vantages of non-crimp and knitted architectures. Non-crimp yarns provide in-plane mechanical properties, whereas knitted yarns provide damage tolerance, toughness, and formability. They are typically produced on flat knitting machines using interlock or rib gating and the loop transfer technique. This study used experimental and numerical approaches to explore the tensile properties of biaxial single jersey knitted (BSJK)-reinforced com-posites. BSJK fabric was produced on a computer-controlled flat knitting machine using nylon 6.6 and jute yarns as knitting and straight yarns, respectively. For preparation of the composite samples, polyester resin was injected into the produced knitted fabric by vacuum-assisted resin transfer molding. Tensile tests were conducted on composite samples in the course and wale directions. After the experimental tests, geometric equations were developed for the BSJK fabric. Then, a meso-scale finite element model was proposed using the developed geometric model in the ABAQUS environment. A user-defined material subroutine was prepared to predict the tensile stiffness, as well as the strength. The findings revealed that the produced BSJK-reinforced composite can be tailored to have excellent in-plane tensile characteristics; moreover, the developed geometric equations can adequately predict tensile behavior.