A novel laminate analogy to calculate the strength of two-dimensional randomly oriented short-fiber composites

In this paper, a new laminate analogy for progressive damage modeling of two-dimensional randomly oriented short-fiber composites is developed. In the present model, two-dimensional randomly oriented short-fiber composite is replaced by an equivalent laminated composite, which contain several unidirectional layers oriented between 0° to 180°. An incremental algorithm is presented to simulate the stress-strain behavior of composites up to the final failure. In the first step, using the shear-lag theory and the Halpin-Tsai method, the on-axis stiffness and strength of each layer were calculated. Then, using the Tsai-Wu failure criterion, damaged layers were detected and the residual moduli of damaged layers were calculated by a random based approach. After failure of each layer, undamaged layers must sustain more stresses. Therefore, the continuum damage mechanics was used to calculate the effective stress in each load increment. A comparison of results of the present model with experimental data available in the literature shows the capability of the model.