Back-Calculation of Elastic Moduli of a Ply from the Moduli of Cross-Ply Laminates

The elastic moduli of composites are typically measured on unidirectional plies. Sometimes, this approach is not possible, and the moduli have to be obtained from multidirectional lay-ups by using back-calculation methods. In such a way, not only ply moduli, but also their standard deviations can be evaluated for arbitrary symmetric cross-ply specimens. In this paper, on the basis of measured experimental data, example calculations are carried out, and the mean values of two elastic moduli and their standard deviations are found. A stacking sequence parameter is defined for a given laminate and a back-calculation strategy, which is shown to control the scatter of the back-calculated moduli.