C/SiC拉伸强度与声发射演化的关联性

Correlation Between Ultimate Strength and Acoustic Emission Evolution of C/SiC During Tensile Failure Process

对平纹编织C/SiC复合材料样品拉伸破坏过程的声发射进行监测,采用基于改进遗传算法的无监督聚类方法对声发射信号进行模式识别,统计分析各类声发射模式的特征及其演化过程,结合断口分析,研究了C/SiC复合材料的拉伸强度、损伤机制与声发射信号演化之间的关系.结果表明:维断裂的声发射能量能够反映纤维/基体界面结合强度;低强度C/SiC材料中存在引起应力集中的基体富集区,在加载初期基体开裂事件占比超过50%;中强度C/SiC材料由于较强的界面,纤维损伤以单丝或部分纤维断裂事件为主;高强度C/SiC材料界面结合强度适中,纤维簇断裂是主要的失效模式.

Acoustic emission(AE)monitoring tests were carried out on the tensile failure process of plain weave C/SiC composites with different strengths.An unsupervised clustering method,based on the improved genetic algorithm,was used to recognize the characteristics of various AE classes,corresponding to different microscopic fracture mechanisms.Combined with the fracture surface observation,the relationship between tensile strength,damage mechanisms,and the evolution of AE signals was analyzed.It is found that:The AE energy of fiber breakage can reflect the bonding strength of the fiber/matrix interface;For the specimen with the lowest strength,there has the matrix enrichment area leading to the stress concentration,and the matrix cracking events account for more than 50%in the initial stage;For the specimen with the medium strength,the failure of fiber are mainly the breakage of single or a few fibers,due to the strong fiber/matrix interface;For the specimen with the highest strength,the integral breakage of fiber clusters is the dominant failure mode,due to the moderate interface bonding strength.