Effect of indenter size on delamination initiation in glass fibre reinforced polymers (GFRP) under transverse loading

It was not clear whether the presence of surface indentation affected the critical load required for the development of delamination from the matrix shear cracking. As this information is essential for finite element modelling to obtain the criteria for delamination initiation and growth, a study was commenced to search for the set-up conditions that could suppress the surface indentation. It was soon discovered that an indenter with a spherical nose of sufficiently large diameter was able to suppress the surface indentation. In this work, indenters of different sizes were used to determine critical load for the on-set of delamination. Based on results obtained from the work, this paper discusses the effect of surface indentation on the critical load for delamination initiation. [Matrix material: isophthalic polyester.]