Behavior of 3-D orthogonally woven composites under tensile loading

A three-dimensional woven fabric composite strength model is presented for predicting the failure behavior of three-dimensional orthogonally woven composites under on-axis, uniaxial, static tensile loading. The representative unit cell is discretized into sections and elements. The method predicts the stress levels at which secondary failures take place at element level. The effect of secondary failure is considered for further analysis, and the ultimate tensile-failure strength and failure strain are predicted. It is observed that for the same fiber volume fractions, 3-D orthogonally woven composites show a significant increase in through-the-thickness properties without a comparable reduction in in-plane properties. It is found that the assumed cross-sectional geometry of the strand with the same overall fiber volume fraction does not make a significant difference to the elastic and strength properties, and hence a square cross-section can be considered