Mechanical Properties of Non-Woven Glass Fibre Composites

The mechanical and impact resistant properties of needle punched non-woven glass fibre composites have been studied. The non-woven composites showed an improvement in mechanical properties with increasing fibre entanglements caused by needle punching. At the same time fibre damage during the needle punching process caused an impairment of performance. Tensile, bending, impact, compression after impact and mode-I tests were performed to investigate the effect of punching density on the mechanical properties. The tensile strength increased with punching density, but the tensile modulus, absorbed impact energy and bending properties decreased. The non-woven composites showed more isotropic mechanical properties with increasing punching density. The energy absorption capability under repeated impact showed a maximum at the low range punching density. The higher the punching density the smaller was the reduction in compression strength after impact. The mode-I interlaminar fracture toughness (G _Ic ) increased with punching density due to the through-the-thickness reinforcing fibres. It was three times as tough as the woven laminate composites. At the optimum punching densities, non-woven composites showed profoundly improved mechanical and impact properties compared with woven laminate composites.