Characterisation of the mechanical and fracture properties of a uni-weave carbon fibre/epoxy non-crimp fabric composite

Abstract

A complete database of the mechanical properties of an epoxy polymer reinforced with uni-weave carbon fibre non-crimp fabric (NCF) is established. In-plane and through-the-thickness tests were performed on unidirectional laminates under normal loading and shear loading. The response under cyclic shear loading was also measured. The material has been characterised in terms of stiffness, strength, and failure features for the different loading cases. The critical energy release rates associated with different failure modes in the material were measured from interlaminar and translaminar fracture toughness tests. The stress-strain data of the tensile, compressive, and shear test specimens are included. The load-deflection data for all fracture toughness tests are also included. The database can be used in the development and validation of analytical and numerical models of fibre reinforced plastics (FRPs), in particular FRPs with NCF reinforcements.

Keywords: Avg, average; CC, compact compression; CFRP, carbon fibre reinforced plastic; CNC, computer numerical control; CT, compact tension; CV, coefficient of variation; Carbon fibre; DCB, double cantilever beam; DIC, digital image correlation; ENF, end notched flexure; FRP, fibre reinforced plastic; FVF, fibre volume fraction; Fracture toughness; MMB, mixed-mode bending; Mechanical properties; Mechanical testing; NCF, non-crimp fabric; NL, nonlinearity method; Non-crimp fabric; Peak, maximum peak method; Polymer matrix composite; R-curve, crack resistance curves; RTM, resin transfer moulding; Stress/strain curve; TT, through-the-thickness; VI, vacuum infusion; VO, visual observation method.

Fig. 1

Photograph of the uni-weave NCF.

Fig. 2

Stress–strain curves of the in-plane tensile and compressive tests; (a) longitudinal tension, (b) longitudinal compression, (c) transverse tension, and (d) transverse compression.

Fig. 3

Specimen failures observed in in-plane tests; (a) longitudinal tension, (b) transverse tension, (c) longitudinal compression, and (d) transverse compression.

Fig. 4

Failure of an in-plane Iosipescu specimen with the full-field strain measurements from the DIC system.

Fig. 5

Stress–strain curves of the shear tests; (a) monotonic in-plane shear, (b) cyclic in-plane shear, (c) monotonic TT shear, and (d) cyclic TT shear. For the cyclic tests the entire response is shown for one specimen, and the envelopes of the stress–strain curves are shown for the other specimens.

Fig. 6

Load–deflection curves (left) and R-curves (right) obtained from (a) DCB tests, (b) ENF tests, and (c) MMB tests.

Fig. 7

Crack path observed on a post-test MMB specimen. The initiation point indicates the end of the initial crack.

Fig. 8

Dimensions of the double waisted specimens.

Fig. 9

Stress–strain curves of the TT tensile (a) and compressive tests (b).

Fig. 10

Failure of the double waisted specimens; in tension (a), and in compression (b).

Fig. 11

Dimensions of the CT specimens (a) and CC specimens (b); in mm.