Analysis of Material Weakening in CFRP after a Drilling Operation

Drilling Carbon Fibre Reinforced Plastics (CFRP) induces different material defects like delamination, burnt matrix material, rough bore channel surfaces, fibre pull-out and uncut fibres. Intensive research has been conducted to analyse the amount of defects caused, describing the surface and subsurface defects introduced by machining operations [1,2]. Additionally, the mechanical strength of rivet joints has been analysed intensively [3]. However, the mechanical performance of rivet joints includes many influencing factors as different materials prepared with various machining processes are being joined. The presented study introduces five newly developed test rigs to analyse the mechanical performance of single bores in relation to different drilling and loading conditions. The setups are designed to focus either on the mechanical strength of the bore channel or the drill entrance or exit. The developed test rigs expand the capability to describe the workpiece quality after a drilling operation. The test rigs facilitate an efficient quality evaluation of drilling processes as well as the development of adapted drilling tools.