Assessment of Liquid Resin Infusion Impregnation Quality Using Scanning Electron Microscopy

Abstract

Fibre reinforced composite materials are increasingly becoming the popular choice of materials for designers in many fields such as aircraft manufacturing. As well as the accompanying high costs, one of their main limitations is the difficulty of making shaped parts such as those of aircraft and UAVs. To overcome this problem, various composite manufacturing techniques have been developed including the vacuum resin infusion (VRI) process and its many derivatives. In this work, a cross ply glass fibre reinforced plastic (GFRP) composite laminate was manufactured using liquid resin infusion (LRI) process which is a derivative of VRI. Specimens cut from the manufactured laminate are tested under static tensile loading and then investigated for resin impregnation quality using two types of state of the art Field Emission Scanning Electron Microscopes (FESEM). Images taken showed some plies with well intralaminar (inter fibre within single ply) impregnation whereas in some locations - within mainly the internal plies - there was very little impregnation. The implication is that unidirectional (UD) laminated when stacked in a cross ply form present another LRI process factor that is not widely investigated. Consequently, infusing UD cross ply composite laminates may present more challenges compared to infusing woven fabrics which are helped by the gaps between the fibres weave and weft.