Concise formula for tensile strength of knitted fabric reinforced composite

A simple one-dimensional formula, as concise as Krenchel's model for stiffness calculation, is presented in this paper to calculate the ultimate tensile strength of a knitted fabric reinforced composite in the loading direction. Its deteriorated form can be used to determine the off axial strength of a unidirectional composite. The formula has been developed based on the understanding of internal stresses generated in the constituent fibre and matrix materials. These stresses are explicitly expressed as functions of the overall applied load, and only the stress components in the loading direction are retained. The ultimate strength of the composite is defined as the overall applied stress under which one of the constituent materials fails. The proposed formula has been applied to calculate the off axial strength of a unidirectional composite and the tensile strengths of two plain weft knitted glass fibre fabric reinforced epoxy matrix composites subjected to wale and course direction loads. All the calculated strengths are in reasonable agreement with experimental data. (C) 2001 IoM Communications Ltd.