Experimental study of tensile and flexural performances and failure mechanism of none-felt needled composites

Abstract

None-felt needled composite material is a novel type of composite with excellent interlayer connection performance. Nonetheless, the tensile and flexural properties and failure mechanism have not been clarified. In this work, none-felt needled fabrics and reinforced composites were manufactured, which were then characterized structurally using Micro-CT. Moreover, the tensile and flexural performances were researched with digital image correlation (DIC) technology, and the fracture morphology was observed employing SEM. The results showed that more needled fiber bundles were implanted along the thickness direction, and the fiber diameter and length were increased by 127.2% and 148.2% respectively. The tensile strengths and modulus also enhanced by 31.5% and 32.8%, and the flexural strengths and modulus improved by 13.1% and 26.7%. The tensile and flexural failure modes of none-felt needled composites and conventional felt needled composites consisted of matrix fracture, in-plane fiber pull-out and brittle fracture. Besides, the flexural specimens of none-felt needled composites had a shorter delamination length. The none-felt needled composites with high tensile and flexural performances are expected to be used in key core components such as radome, cabin and skin of hypersonic aircraft.