Tensile behaviors of nanoporous phenolic composites reinforced by 3D needle-punched preforms with different weave patterns

Abstract

Needle-punched preform reinforced nanoporous phenolic composite (NPC) is a cost-effective lightweight ablative material for thermal protection systems. It consists of a needle-punched preform composed of alternating stacked fiber felt and stacked woven fabric, which plays a crucial role in the thermal insulation efficiency and mechanical properties. Herein, needle-punched preforms with different types of fabrics, including plain, twill, and satin, are deliberately designed for the reinforcement of NPC, and their tensile properties and fracture mechanism are investigated through experimentation and the CT image-based finite element method. At the same preform density, the composite with plain fabric exhibits the highest tensile strength of 146 ± 6.3 MPa, a tensile modulus of 8.2 ± 0.2 GPa, and an elongation of 2.1 ± 0.1%, due to having the highest number of crossover points and the largest undulation of fiber yarns. Furthermore, the CT image-based simulation reveals the failure mechanism of NPC. The von mises stress of woven fabric is higher than that of fiber felt, which demonstrates the woven fabric is the main load-bearing structure and determines the mechanical of composite. These results will provide useful guidance for the structural design and optimization of needle-punched preform reinforced composites.