Impact properties of weft knitted fabric reinforced composites

The impact properties of weft knitted fabric composites have been investigated based on their fracture toughness and tensile properties. The fracture toughness of knitted fabric composites was investigated by using double cantilever beam (DCB) tests. The delamination resistance of knitted fabric composites was studied by using the measured fracture toughness values in a simplified delamination model. As forces required to create a delamination are higher than the ultimate impact force, knitted fabric composites do not fail in delamination failure mode. Knitted fabric composites tend to fail in flexural mode, either in compression at the impacted area or in tension at the bottom side, opposite to the impacted area. Therefore, it is interesting to compare the impact properties of weft knitted fabric composites with their tensile properties.