3d Woven Composites for Energy Absorbing Applications

Due to the presence of through-thickness reinforcement, 3D woven composites have superior fracture toughness, fatigue life, and damage tolerance compared to laminated composites. Furthermore, 3D woven composites exhibit a progressive damage behavior which is more benign than the typical catastrophic failure behavior of laminated composites. These properties lead to high specific energy absorption (SEA); making 3D woven composite parts suitable lighter weight replacements to those manufactured using traditional materials such as laminated composites or highstrength metals. The goal of this study was to demonstrate these characteristics by comparing the performance of a 3D woven composite beam loaded in three-point bending to that of a similar beam made from high-strength steel (HSST). This was achieved by taking a combined experimental and simulation approach for both materials. Constant cross-section 3D woven composite beams were manufactured for this study using an aerospace grade carbon fiber and toughened epoxy resin. The composite beams and vehicle side intrusion beams made of HSST were tested in three-point bending quasi-statically. Both experiments were modeled at the macro-scale, i.e. continuum level, with nonlinear finite element models that captured progressive failure and crushing behavior for the composite beam and the plasticity of the metal beam. The experimentally validated HSST material properties were then used to simulate the load-displacement behavior of a constant cross-section HSST beam that had an adjusted thickness to match the peak load of the composite beam. The results of the study showed that the 3D woven composite beam designed to carry the same peak load of a HSST beam has 37% higher SEA under three-point bending.