Mechanical and Impact Properties of Needle Punched Nonwoven Composites

Abstract

The effect of changes in fiber structure on the mechanical properties of nonwoven composite with different punching densities was studied through the testing of tensile, bending, impact, compression after impact, fatigue, friction/wear and mode-I interlaminar fracture properties. The tensile strength and mode-I interlaminar fracture toughness of nonwoven composite was increased with increasing punching densites due to the increased fiber entanglement. The flexural, impact, fatigue and wear properties were decreased with punching densities due to the damage to fibers during the punching process which resulted in the reduction of fiber length. The impact resistant properties showed its maximum at the punching density of 30penetration/cm2. The tensile modulus and the compression strength were determined from the orientation of the reinforcing fibers which was affected with the punching densities. The mechanical properties of nonwoven composite showed rather isotropic properties with increased random distribution of the fibers at high punching densities. In the range of adequate punching densities, the nonwoven composite showed substantially improved mechanical and impact properties compared to the woven laminate composite. The nonwoven composite showed improved properties of flexural and compression strengths as well as mode-I interlaminar fracture toughness.