Finite element modeling of multiple transverse impact damage behaviors of 3-D braided composite beams at microstructure level

摘要

Multiple transverse impact damage behaviors of 3-D braided composite beams with various braiding angles were investigated from finite element analyses (FEA) and tests in different impact energies. The impact behaviors were tested with a modified split Hopkinson pressure bar (SHPB) to obtain impact load-displacement curves during several stress wave periods. The impact deformations were photographed with a high-speed camera. Based on observations of the microstructure of the 3-D braided composites, a microstructure model was established for finite element calculation. In this model, the cross-section of braided yarns is regarded as hexagonal. We found that the impact peak load decreased gradually as the impact cycle continues due to the impact deformations and damages. The samples with greater braided angle have higher resistance of transverse impact fracture. The impact stress wave propagates along braided yarn path direction which leads to higher stress level at impact location in incident surface and the opposite location in backward surface. The braided composite with smaller braided angle has higher in-plane and transverse impact stiffness, while higher braided angle has higher transverse impact fracture resistance and impact stiffness.