Tensile extension properties and deformation mechanisms of multiaxial non-crimp fabrics

The deformation resistance and mechanisms of biaxial and triaxial non-crimp fabrics under bias extension loading is experimentally investigated. The bias deformation resistance of multiaxial non-crimp fabrics is found to be substantially lower than conventional single layer woven fabric due to the unique deformation mechanisms of rotation, sliding and compaction of the fibre tows. It is shown that the amount, line-tension and location of the warp-knitted stitches used to bind non-crimp fabrics have a major influence on the bias deformation resistance. It is found that lowering the amount and line-tension of the stitches facilities the tow sliding mechanism that reduces the deformation resistance of non-crimp fabrics. Fabric deformation is also affected by the location of the stitches, with stitches that pass between, rather than through, the tows reducing the resistance to bias deformation, again due to increasing ease of the tow sliding process. The warp knitting conditions needed to maximise the deformation limits of non-crimp fabrics are determined.