Damage analysis and notch sensitivity of hybrid needlepunched nonwoven materials

Needlepunched nonwovens are complex three-dimensional (3D) entangled fibrous materials which are extensively used for a range of technical and industrial applications. The micromechanisms of deformation and fracture behavior of these materials are complicated and least understood. In this study, the tensile behavior of virgin and notched samples is investigated for hybrid needlepunched nonwoven materials consisting of polypropylene and viscose fibers in defined proportions. The notches in nonwovens were induced by two types of mechanical damage (circular hole and vertical cut) in three spatial positions of hybrid nonwovens tested in the machine, 45°, and cross-machine directions. The notch sensitivity of hybrid nonwovens was demonstrated by localized fiber failures occurring around the region of induced damages. It was established that the shape and spatial position of induced damage have significant influence on the tensile behavior of hybrid nonwoven materials. Higher viscose contents (60–80 wt%) in notched hybrid nonwovens yielded minimal tensile strength reduction specifically in the preferential (cross-machine) direction.