复合材料层压板抗冲击行为及表征方法的实验研究

Experimental study on the behavior and characterization methods of composite laminates to withstand impact

对14种复合材料体系约800个试样进行了冲击阻抗和含损伤层压板压缩强度试验研究,研究发现对于同一种复合材料层压板的冲击能量-凹坑深度曲线和凹坑深度-压缩破坏应变曲线均存在拐点,在出现拐点后内部的分层损伤叠加面积基本不再增加,压缩剩余强度基本不再降低,表面冲击部位开始出现纤维断裂。研究表明,采用传统CAI来表征损伤容限性能的方法可能得到与实际结构损伤容限特性相反的结论。因此,提出了利用拐点附近特性来表征复合材料层压板的抗冲击行为(包括损伤阻抗和损伤容限)的建议,即分别采用QSI方法得到的准各向同性层压板的最大接触力Fmax和压缩破坏强度(应变)的门槛值CAIT来表征复合材料层压板的损伤阻抗和损伤容限行为。

An experimental study on the impact resistance and compressive strength of damaged laminates was carried out by using about 800 specimens of 14 composite systems. It has been found that there is a common knee point for the impact energy-dent depth curve and the dent depth compressive strength curve for the same type of composite laminates. The overlapped area of the inner delaminations does not increase and its compressive strength does not reduce generally after the knee point occurs. Some fiber breakage at the impact location on the surface could be visible after the knee point occurs. The damage tolerance behavior characterized by the traditional CAI method may get the opposite conclusion obtained from the structural verification test results. Therefore, a characterization system for damage tolerance and damage resistance behaviors of composite systems is proposed by using the knee point features of the capability of composite laminates to withstand impact （including damage resistance and damage tolerance）, i.e. the damage resistance and damage tolerance behavior is characterized by means of the maximum contact force, Fmax and the compressive failure threshold value （strength or failure strain） （CAIT） of the specimens with quasi-isotropic stacking sequence respectively.