Abstract This work performs acoustic emission monitoring of damage behaviors in carbon fiber/ epoxy composite laminates during tensile loads under hygrothermal environment. First, a waveform-based clustering method is introduced by employing the wavelet packet decomposition (WPD), the Shannon’s entropy, the cosine similarity and the clustering algorithm. Second, based on the clustering results, the characteristic features of various damage modes are derived. Finally, further investigation is carried out to explore the effects of hygrothermal aging on the damage source localization, damage initiation and evolution. From the theoretical analysis, several conclusions are obtained: 1. Fiber breakage behaves as a combination of matrix cracking, fiber/matrix interface debonding and delamination in the space of extracted features. 2. The frequency response of each damage mode is demonstrated to be degraded after hygrothermal aging. The principal features of fiber/matrix interface debonding and delamination are found to be significantly affected by hygrothermal aging as compared to other two damage modes. 3. The distortion of the principal feature of each micro-damage mode is found to be negligible with the damage accumulation, indicating the robustness of the method.

中文翻译：

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湿热环境下复合材料层合板损伤模式识别的波形聚类方法

摘要 这项工作对碳纤维/环氧复合材料层压板在湿热环境下拉伸载荷期间的损伤行为进行声发射监测。首先，采用小波包分解(WPD)、香农熵、余弦相似度和聚类算法，介绍了一种基于波形的聚类方法。其次，根据聚类结果，推导出各种损伤模式的特征。最后，进一步研究了湿热老化对损伤源定位、损伤发生和演化的影响。从理论分析中，得到几个结论： 1. 纤维断裂表现为基体开裂、纤维/基体界面脱粘和提取特征空间中的分层的组合。2. 每种损坏模式的频率响应都被证明在湿热老化后会降低。与其他两种损伤模式相比，纤维/基质界面脱粘和分层的主要特征被发现受湿热老化的显着影响。3.发现每种微损伤模式的主要特征的失真随着损伤累积可以忽略不计，表明该方法的鲁棒性。