Flexion in composite materials with different tensile and compressive response

Abstract

An analytical and experimental study of flexural testing on laminates formed by layers of unidirectional carbon-fibres pre-impregnated with an epoxy resin is presented. Among other stacking sequences, the configuration comprised by groups of ±45° is of interest in the transport industry in which often there are structural parts subjected simultaneously to bending moments and shear forces. Having as a reference the three-point flexural testing, the work is focused on taking into account the different response of the material under tensile and compressive loads. From the experimental point of view, the damage initiation and evolution of the material are proposed to be visualized by means of optical methods and microscopy techniques, comparing the experimental observations with the analytical estimations. The analytical model used is based on the technique of homogenized section and it allows to predict the initial failure mode that will occur experimentally depending on the thickness of the specimen.