角联锁机织复合材料的面内高速冲击破坏过程

In-plane high-speed impact damage of angle-interlock woven composite

制备层层结接角联锁机织复合材料。采用高速摄影方法采集冲击加载瞬间复合材料面内变形、裂纹扩展和渐进破坏细节,并将高速破坏帧图与应力-应变曲线的每个阶段对应。实验研究表明:面内冲击加载下的角联锁机织复合材料在达到其最大应力后将经历应力快速衰退(裂纹扩展与演化关键阶段)和应力缓慢衰退(持续破坏阶段)两个阶段。相比于面内经向受载,面内纬向受载时复合材料具有更高的模量和强度。且经向和纬向具有明显不同的高速破坏过程:经向受载时,层间裂纹沿着经纱屈曲路径扩展,迅速形成遍布材料厚度方向的多条剪切带而导致材料彻底碎裂;纬向受载时,层间裂纹只在面内方向演进,始终未能突破厚度方向上的经纱束缚,具有较强的抗冲击分层效果。

Layer-to-layer angle-interlock woven composite was fabricated. In-plane deformation, crack propagation and progressive failure of the angle-interlock woven composite were investigated with high-speed imaging during impact loading. Real-time images from high-speed damage were listed frame by frame and matched with each stage of the stress-strain curve. It is found that after reaching the maximum stress, the angle-interlock woven composite undergoes a sharp stress decrease stage and a slow stress decrease stage. The sharp stress decrease stage reveals the critical stage of crack propagation and evolution, while the slow stress decrease stage indicates the progressive failures. Compared with the in-plane warp-direction impact loading, much higher modulus and strength of the composite can be obtained from in-plane weft-direction impact loading. And different high-speed damage behaviors can be identified from these two loading processes. For the former case, dispersive shear cracks are accumulated along the warp/matrix interfaces and propagated through several layers of the composite. Specimens are fractured by shear-delamination cracks along the paths of warp yarns due to the lack of binding effect of straight weft yarns. While for the latter case, inter-laminar cracks are developed at weft/matrix interfaces, which cannot breakthrough the warp yarn constraint along the thickness, showing a stronger anti-impact effects and protecting the composite from delamination.