碳纤维复合材料超声扫描分层检测及评价方法

由于碳纤维增强复合材料（CFRP）具有各向异性的特点，在其钻削加工中极易形成分层、撕裂以及毛刺等加工缺陷，而分层对碳纤维层合板构件的性能影响最大，因而建立一套准确的针对分层缺陷的检测、描述以及评价方法对层合结构碳纤维复合材料的有效应用具有重大意义。从分层缺陷的形成机理出发，通过对现有分层缺陷的检测以及评价体系的分析，提出了基于高频超声扫描显微镜（SAM）来进行分层缺陷检测评价的三维体积分层因子评价方法，并针对T800/X850碳纤维单向层合板对该方法进行了定征试验，最后通过对实际加工孔的分层缺陷的评价，综合对比了三维体积分层因子评价方法与传统评价方法的应用效果。结果表明：分层缺陷是由力热耦合引起的层间粘结失效，出口处更为严重；用超声扫描显微镜检测分层，可检测不少于8层的碳纤维复合材料，至少可以清晰表达5层的内部分层特征；分层会发生隔层传播，并且两个相邻铺层为同向的层间结合强度最好，不易产生隔层传播；三维体积分层因子可以更准确清晰地评价复合材料层合结构的内部缺陷。

CFRP ultrasonic scan delamination detection and evaluation method

Because of the anisotropy, carbon fiber reinforced plastics (CFRP) materials are prone to form machining defects in drilling processes, such as delamination, tearing and burr, among which delamination has the most important influence on composites properties. Therefore, it is essential to establish a set of methods to detect and evaluate delamination clearly. Based on the mechanism of delamination and analysis of current detection and evaluation methods, a kind of 3-D delamination factor evaluation method is proposed by high frequency scanning acoustic microscope (SAM), and delamination characteristics of T800/X850 are identified based on SAM. Finally, the results were also compared between 3-D delamination factor method and traditional methods. The results show that delamination defects are caused by mechanical-thermal coupling which may induce interlayer bonding failure and the exit is more serious. What's more, delamination of no less than 8 layers in CFRP could be detected by SAM and internal layered characteristics of at least five layers could be obviously detected. Delamination could be transferred to other layers and interfacial bonding strength shows the best when the adjacent layers are in the same orientation. Moreover, 3-D delamination factor could evaluate the internal defects of composite laminates more accurately.