The influence of stitching fibre and stitching density on the failure strains of CFRP fabrics

摘要

In this paper the results are described of an experimental programme in which the influence of stitching fibre and stitching density on the failure strains of carbon fibre fabric/epoxy laminates, impregnated by Resin Transfer Moulding (RTM), wasinvestigated by carrying out static compression and tension tests. The results were compared to results of typical unidirectional prepreg specimens made in the autoclave.The compression tests revealed that stitching did not result in a significant improvement of the allowable strain levels, due to the presence of circumferential roving reinforcements in the RTM fabric. Better results are expected without suchreinforcements.The compression after impact tests showed that failure strain levels for stitched and unstitched RTM specimens are almost equal to failure strain levels for autoclave specimens.The tension tests revealed that high density stitching (10 stitches/cm{sup}2) results in a severe reduction of the tension failure strains compared to unstitched values. A stitching density of 4 stitches/cm{sup}2 will result in a small reduction oftension failure strain.The stitching fibre type, Kevlar or Dyneema, has no influence on the failure strain levels.