Progressive failure analysis of laminated knitted fabric composites under 3-point bending

Abstract

The bending behavior of laminated beams reinforced with differently arranged plain-weft knitted fabrics has been investigated in this paper. Experiments were carried out to measure the bending stiffness and strength of six layers knitted fabric reinforced epoxy composite laminates under 3-point bending. The laminate lay-ups of [0/0/0/0/0/0], [90/90/90/90/90/90] and [0/-45/45/45/-45/0] have been taken into account, where 0 denotes that the fabric wale direction is arranged along the beam axial direction. A simulation procedure is presented to analyze the bending property of the laminated beams based on the bridging micromechanics model and the classical lamination theory. It has been found that the use of a stress failure criterion only is no longer enough for estimating the ultimate bending strength of the laminate. An additional critical deflection condition is also required. By using only the constituent properties, which were measured using bulk material specimens independently, and the fabric knitting and lay-up parameters, the predicted stiffness and strength agree favorably with the experimental data.