The Effect of Compaction on the Compressive Properties of a 3D Woven Interlock Fabric

3D-woven fabrics incorporate through thickness reinforcement and can exhibit remarkable interlaminar properties that aid damage suppression and delay crack propagation. However, distortions in the internal architecture such as yarn waviness can reduce in-plane properties, especially in compression. The degree of yarn waviness present in a 3D woven fabric can be affected by a range of factors including weave parameters and manufacturing-induced distortions such as fabric compaction. This paper presents a through analysis of the effect of yarn waviness and fabric compaction on the mechanical properties and failure mechanisms of an angel-interlock fabric loaded in compression. Uniaxial compression tests were conducted on coupons moulded to different volume fractions and compression mechanical properties data compared to previous measurements on local yarn angle. Failure was also monitored in real time by high speed video and post failure damage pattern inspected by X-ray computer tomography. Major findings include the importance of optimising yarn straightness to improve compression strength and how this can be affected by choosing an optimum moulding thickness. Failure initiation was also found to be heavily influenced by weave style and yarn interlacing.