The effect of crimp geometry on the mechanical properties of nonwoven fabrics of different punching densities was studied. The theoretical modulus of crimped fiber assembly was derived and the three factors that affect the contact behavior between fibers in nonwoven fabrics were specified. If the crimped yarn has the same volume and orientation density function as the flat fiber, the contact points were increased proportional to the square of the crimp ratio. The crimp in the yarn acts as the slip barrier, which results in the decrease in slip portion of contact points as well as the contact point load, and thus it results in the increase of the yarn modulus. The modulus of the needle punched nonwoven made with crimped fiber varied with the contact length of the fiber. As the contact distance between two adjascent fiber decreases, the effect of crimp diminishes. These factors generally increase the modulus of the nonwoven fabrics. Especially in bending properties, the increased crimp potential and number of contact points contribute to the increase in bending rigidity along with increasing thickness. Post treatment of the nonwoven fabrics after needle punching removes the residual moment in the nonwoven system and it helps the resilience properties of the nonwoven.
