Photoelastic study of stresses in the vicinity of a unique void in a fibre-reinforced model composite under compression

The subject of this work is the investigation of the stress field around a unique void in a fibre-reinforced model composite under compression. Voids were introduced into the epoxy material by injection. The idea was to imitate a real void in fibre reinforced plastics (FRP) where voids appear between fibres and in resin rich areas. To investigate the mechanical response of the composite material under compression, a test jig was designed, which fits into a light microscope with an integrated photoelasticity device. That way in situ measurements were conducted. It could be demonstrated, that voids have a significant influence on the stress distribution in the matrix which leads to stress concentrations particularly around the end caps and the longitudinal side of the voids. Furthermore, different failure mechanisms like fibre matrix debonding and fibre buckling could be observed.