Implementation and validation of a semi-analytical method for the prediction of material allowables for unidirectional composite materials

Abstract

Composite materials have very appealing properties. They are both lightweight and resistant, making their use of prior importance in reducing energy consumption in aeronautics and automotive sectors for instance. They are also widespread in the wind industry. However, the understanding of their behavior up to rupture is still an open question. Lot of work has been done in using advanced non-linear finite element models to predict ultimate failure of composites. Unfortunately, these methods result in very high computational costs, and generally require extensive material characterization, and as a result, material screening and preliminary optimization price goes up. In order to tackle both problems of computational costs and material characterization, this report implements and validates a semi-analytical framework for computing the strength of open-hole unidirectional Carbon Fiber Reinforce Polymer composite laminates. The framework requires only the longitudinal modulus and strength of the zero ply, as well as its R-curve. Since the method does not involve finite elements, it is both time and mesh size independent and extremely fast. In this work, the method will be evaluated on several datasets. Afterwards, a method for calibrating the R-curve from one open-hole strength is introduced to relieve the material characterization. Finally, the unnotched strength criterion used in the method will be enhanced. The overall framework performs very well at capturing the hole size effect on open-hole strength of unidirectional laminates, considering that very few material properties are used.