An Investigation of Wrinkling Behaviour in Woven Thermoplastic Composite Material

Abstract

This work is designed to develop a viable universal indicator to predict the onset of wrinkling for woven thermoplastic fiber-reinforced composite materials. A range of experiments on Yoshida test are carried out to investigate the local strain behaviour at the onset of wrinkling. An approach of using the abrupt change in the slope of the evolution of the strain path to predict the onset of wrinkling is proposed in this study. This approach is the first of its kind in predicting the onset of wrinkling. Different metrics in the quantification of abrupt change in the slope of strain path are examined and compared. A wrinkling indicator of using strain increment ratio to predict the onset of wrinkling is the fundamental contribution of the present work. The validity of this indicator is explored in a series of the dome forming experiments involving composite materials and steel. The results reveal that this proposed indicator can accurately predict the onset and the propagation of wrinkling in Yoshida test and dome forming operations. This indicator is also applicable to other class of materials. Analytical approach of using energy approach at a small wrinkling affected region (effective region) is also developed to predict the onset of wrinkling in Yoshida tests. This approach provides a direct relationship between the critical wrinkling stress and material properties, boundary conditions and geometrical parameters. Show more