Dynamic compressive behavior in different loading directions of 3D braided composites with different braiding angle

Abstract Dynamic compressive tests of 3D braided composites with different braiding angle were carried out in the longitudinal, transverse and thickness directions respectively using the Split Hopkinson pressure bar (SHPB). The results show that the compressive properties present obvious strain rate strengthening effects in all directions. The 20° and 45° braided composite are most sensitive to strain rates in the longitudinal direction. The composites present the features of brittle failure at high strain rates, especially in the longitudinal direction. The composites with larger braiding angle have weaker mechanical properties in the longitudinal and transverse directions but stronger mechanical properties in the through-thickness direction. The braid angle has the greatest impact on the longitudinal mechanical properties. The compressive stress-strain curves in the thickness direction were similar to the hysteresis curve for both the 30° and 45° braided composites. The compressive failure modes vary with the loading directions and strain rate.

摘要：采用分离式霍普金森压杆（Split Hopkinson pressure bar, SHPB），分别沿纵向、横向与厚度方向，对不同编织角的3D编织复合材料开展动态压缩试验。研究结果表明，所有测试方向下复合材料的压缩性能均呈现显著的应变率强化效应。其中20°与45°编织复合材料在纵向对应变率最为敏感。高应变率条件下，该类复合材料表现出脆性断裂特征，纵向方向尤为突出。编织角更大的复合材料，其纵向与横向力学性能相对更弱，但厚度方向力学性能更强。编织角对纵向力学性能的影响最为显著。30°与45°编织复合材料的厚度方向压缩应力-应变曲线均与滞后回线相似。压缩失效模式随加载方向与应变率的变化而改变。