Mechanical properties of PVC coated bi-axial warp knitted fabric with and without initial cracks under multi-axial tensile loads

The paper presents a study on the mechanical properties of PVC coated bi-axial warp knitted fabric with and without initial cracks under multi-axial tensile loads. The mechanical behaviors of the same coated fabric under mono-axial and multi-axial tensile testing conditions are compared. The influences of the initial crack length and orientation on the mechanical performance are analyzed. It is found that while the coated fabric demonstrates anisotropic properties under mono-axial tensile condition, the same fabric rather behaves more isotropic under multi-axial tensile loads. It has also found that the mechanical performance decreases with increase of the initial crack length for a given crack orientation, and that the initial crack orientation perpendicular to a tensile direction has a maximal effect in the reduction of the mechanical performance in this direction. The crack propagation is always progressively along the weft direction of the fabric under multi-axial tensile condition no matter how the initial cracks are orientated.