2.5D C/C编织复合材料损伤演化试验研究

Experimental study on damage evolution of 2.5D C/C braided composites

为研究2.5D C/C(碳/碳)编织复合材料的失效机理,对矩形截面试样开展损伤演化模拟试验.针对轴向加卸载过程中的应变响应,使用弹性模量法逐级计算试样损伤值,研究其损伤演化过程和规律;结合试样断口分析,总结不同失效模式对应的损伤效应.试验结果表明:2.5D C/C编织复合材料的失效位置具有分散性,失效模式具有多样性特征;分层破坏时损伤累积较小,损伤值达到10%~13%时试样即发生破坏,且裂纹只在层间扩展;纤维拔出和断裂时损伤累积效应较明显,在试样断口附近正反两面损伤演化过程均较显著,损伤值达到20%~25%时试样破坏.

In order to study the failure mechanism of 2.5D C/C(carbon/carbon)braided composites,the damage evolution experiment was carried out on rectangular cross-sectional specimens.By monitoring the strain response during the loading and unloading cycle process,the progressive damage value was calculated based on the elastic modulus method and the damage evolution process was studied.Combined with the fracture analysis of the post-break sample,the damage effects in different failure modes were summarized.The experimental results show that the damage initiation of 2.5D C/C braided composite is random while the failure mode is different.Delamination failure appears with a low-level damage accumulation(about 10%to 13%)and the crack only extends between layers.According to fiber pull-out and fracture mode,the damage accumulation is significant near the fracture on both front and back sides of the specimen.The specimen is destroyed when the damage value reaches up to 20%to 25%.