High‐temperature short‐range compressive responses and contact effect of ultrahigh porosity 3D random fibrous materials

Abstract Through experiments and finite element modeling ( FEM ) of contacting fibers, we study the compressive responses of a 3‐dimensional (3D) random fibrous ( RF ) material of ultrahigh porosity (89%) in the through‐the‐thickness ( TTT ) and in‐plane ( IP ) directions from 299 (room temperature) to 1273 K. The experimental results indicate that localized failure and overall compressive deformation dominate the deformation process of RF materials loaded in the TTT direction at low and high temperatures, respectively. On the other hand, only localized failure is observed in the IP direction upon loading. Based on its morphological characteristics, a FE model that considers contact between the fibers is developed to simulate the compressive responses of the tested 3D RF material. In this model, the contact mechanism between the fibers is simulated based on a user‐defined nonlinear spring element. The simulated strength and elastic modulus agree well with the observations from the compressive experiments.