Effects of shear-transverse coupling and plasticity in the formulation of an elementary ply composites damage model, part II: Material characterisation

In this two-part study, we examine the effects of neglecting plasticity and shear-transverse coupling in a continuum damage mechanics model for composites. In part I, two models were formulated: one in which plasticity was neglected, and one in which both plasticity and shear-transverse damage coupling were neglected, and the predictive capabilities for both models were examined. In this second part of the paper, the procedure and results of the experimental test series carried out to determine input parameters for the above two models are presented. Two materials were tested: one a carbon fibre-reinforced plastic, the other an S2-glass fibre-reinforced plastic. Both material systems are currently used in the aerospace industry so the experimental results should be of interest to that community. Both materials exhibited non-linear intralaminar shear behaviour, whereas the S2-glass fibre-reinforced plastic also exhibited a significantly non-linear transverse response. Tests on ±45° and 10° off-axis coupons indicated that a reasonable estimate of shear strength could be obtained from the ±45° test specimens. Some further insight is provided into the model predictions that were presented in part I.