A Study on Frequency Analysis of Acoustic Emission in Composite Materials

将复合材料的微断裂机理划分为基体微断裂、纤维断裂、分层和基体断裂，在实际应用中具有重要意义。利用与声发射参数最拟合的频谱研究了微断裂机理。采用CFRP模型对常规CFRP的微断裂机理进行了研究。CFRP模型中基体微开裂、基体开裂、基体与纤维脱粘、基体与纤维摩擦或纤维断裂的频谱分别为260、50 ~ 100、150 ~ 250和270 ~ 390 KHz。常规复合材料和单向复合材料中基体开裂、脱粘、基体与纤维摩擦或纤维断裂的频谱分别为50 ~ 100 KHz、150 ~ 250 KHz和270 ~ 390 KHz。常规碳纤维复合材料和三向碳纤维复合材料的频谱包含630 KHz的频率，而模型碳纤维复合材料不包含这个频率，它是由纤维之间的摩擦在分层时产生的。其次，在a类smc复合材料中，基体开裂、碳酸钙开裂或基体与碳酸钙脱粘、基体与纤维脱粘或纤维拔出、纤维断裂的频率分别为80 ~ 180khz、240 ~ 450khz、180 ~ 250khz和250 ~ 400khz。结果表明，频率分析可以明确复合材料的断裂机理。

It is important to classfy the microfracture mechanisms of composite materials such as the micro-cracking in matrix, the fiber breaking, the delamination and the matrix cracking in pratical use. The microfracture mechanisms are studied by the frequency spectrum, which is most fitted in the AE wave parameters.The microfracture mechanisms of convential CFRP is studied by using model CFRP. The frequency spectra of the micro-cracking in matrix, the matrix cracking, the debonding between matrix and fibers, and the friction between matrix and fiber or the fiber breaking in model CFRP are 260, 50-100, 150-250 and 270-390 KHz, respectively. The frequency spectra of the matrix cracking, the debonding, and the friction between matrix and fibers or the fiber breaking in the conventional and unidirectional CFRP laminates are 50-100, 150-250, and 270-390 KHz, respectively. The frequency spectrum of conventional and three directional CFRP laminates contains the frequency of 630 KHz, which the model CFRP does not contain and it is generated by the friction between fibers at the delamination.Next, in the class A-SMC composite material, the frequencies of matrix cracking, the calcium carbonate cracking or the debonding between matrix and calcium carbonate, the debonding between matrix and fibers or the fiber pulling out, and the fiber breaking are 80-180, 240-450, 180-250 and 250-400 KHz, respectively.It is found that the fracture mechanisms of composite materials can be clarified by the frequency analysis.