Transverse biaxial tests on long fibre reinforced composites

Abstract

The study and prediction of the failure mechanisms affecting long fibre reinforced composites is a fundamental field that provides an essential knowledge for the structural design with composites. Transverse failure, generated at ply level by the mechanism of damage known as inter-fibre/matrix failure, usually determines the damage initiation in any laminate which justifies its relevant role and the need to understand its micromechanical stages. Previous numerical results established that in the case of transverse biaxial loads (T-nT and T-nC cases) the stages of the damage mechanism detected in the uniaxial case could be affected. The most outstanding conclusion anyhow was that the effect of a secondary tension did not significantly alter the ultimate value of the tension nominally responsible for the failure, whereas a secondary compression could advance the failure appearance. In order to experimentally check the validity of these conclusions the performance of transverse biaxial tests is undertaken in this paper. The present investigation begins with the presentation of the cruciform geometry selected for the specimen and is followed by the description of the specific manufacturing procedure employed. The results of the testing campaign carried out agree with the previous numerical prediction and provide relevant information for the prediction of failure initiation.