Edge Finishing Effects on Mechanical Properties of Composite Laminates

Abstract

Edge Finishing processes used in this study included Abrasive Water Jet and Carbide Router Endmilling for the trimming of the laminate material. For drilling of holes in the laminate material, Polycrystalline Diamond drills and Chemical Vapour Deposition (CVD) diamond coated carbide drills were used. Test material was machined with these processes and resultant surface integrity was recorded using a Surface Profilometer, Edge Replication using acetate tape and Scanning Electron Microscopy (SEM). The machining processes result in macroscopic defects which lead to the damage evolving with service loadings which can result in failure of the CFRP laminates in service. This study was conducted to research the effects of machining processes on residual strength of laminates. A 20 ply thick balanced symmetric [90/-45/0/-45/90/45/0/-45/0/90/0]s laminate was used in this study with a nominal thickness of 4.19 mm and with an average ply thickness of 190 μm. The laminate had a top layer of woven fabric material [0/90] and a bottom layer of fiberglass skin material. Mechanical testing was conducted on test specimens to failure for the tensile strength, compressive strength, open-hole tensile strength, open hole compressive strength and bearing strength. The failure mode and damage of the test specimens for each case was examined and discussed.