Influence of voids on the compressive failure behaviour of fibre-reinforced composites

The subject of this work is the micromechanical investigation of the influence of voids on the compressive failure behaviour of fibre-reinforced polymers (FRP). Although, the effect of void content on the mechanical properties was investigated in previous literature, a local examination of the failure mechanisms is essential to understand how the presence of voids reduces the compressive strength in FRP. Therefore, the complex three dimensional structure of a composite, including several voids, were analysed and a reduced mechanical model composite (focusing on one unique void) was derived. The experimental investigation of the model composite included the description of the stress- and strain behaviour of the matrix using photoelasticity. Additionally, a numerical examination of a parameterised model composite was conducted. From the experimental studies the failure initiation and propagation could be observed. Supported by the findings from numerical simulation, foundation and alignment of fibres as well as fibre-matrix bonding has the most impact on the failure initiation.