The formation of multiple delaminations is a frequently observed damage mechanism in composite materials, exerting a more pronounced influence on their strength properties compared to single delaminations. To tackle this issue, the incorporation of nanoparticles has been investigated as a means to enhance composite materials. This study aims to examine the effects of nano-additives, specifically carbon nanotubes and nanosilica, on the flexural behavior of glass/epoxy composites containing multiple embedded delaminations. The acoustic emission technique is employed to gain deeper insights into the damage mechanisms associated with flexural failure. Artificial delaminations of varying sizes, arranged in a triangular pattern, were introduced into four interlayers of a [(0/90)]s oriented glass/epoxy composite. The findings reveal a notable reduction in flexural properties due to the presence of multiple delaminations. However, the addition of nanoparticles demonstrates a significant improvement in the flexural behavior of the multi-delaminated specimens. The most substantial enhancement is observed in the composite incorporating 0.3 wt% nanosilica + 0.5 wt% carbon nanotubes. Furthermore, genetic K-means and hierarchical clustering techniques are employed to classify different damage mechanisms based on the peak frequency and amplitude of the acoustic emission signals. The results indicate that the hierarchical clustering method outperforms the genetic K-means method in accurately clustering the acoustic emission signals. Moreover, the incorporation of nanoparticles' impact on the occurrence of distinct damage mechanisms is evaluated through the analysis of acoustic signals using Wavelet Packet Transform. By investigating the flexural behavior of nanomodified multi-delaminated composites and employing the acoustic emission technique, this study offers valuable insights into the role of nanoparticles in enhancing the mechanical properties and monitoring the damage mechanisms of composite materials.

中文翻译：

---

使用声发射技术研究纳米改性多层复合材料的弯曲行为

多重分层的形成是复合材料中经常观察到的损伤机制，与单一分层相比，其对其强度性能产生更显着的影响。为了解决这个问题，人们对纳米粒子的掺入进行了研究，作为增强复合材料的一种手段。本研究旨在研究纳米添加剂，特别是碳纳米管和纳米二氧化硅，对含有多个嵌入式分层的玻璃/环氧树脂复合材料的弯曲行为的影响。采用声发射技术来更深入地了解与弯曲失效相关的损坏机制。将不同尺寸的人工分层以三角形图案排列，引入[(0/90)]s取向玻璃/环氧树脂复合材料的四个夹层中。研究结果表明，由于存在多重分层，弯曲性能显着降低。然而，纳米粒子的添加表明多层分层样本的弯曲行为得到了显着改善。在包含 0.3 wt% 纳米二氧化硅 + 0.5 wt% 碳纳米管的复合材料中观察到最显着的增强。此外，采用遗传 K 均值和分层聚类技术根据声发射信号的峰值频率和幅度对不同的损伤机制进行分类。结果表明，层次聚类方法在对声发射信号进行准确聚类方面优于遗传K-means方法。此外，通过使用小波包变换分析声信号来评估纳米颗粒的加入对不同损伤机制发生的影响。通过研究纳米改性多层复合材料的弯曲行为并采用声发射技术，本研究为纳米颗粒在增强复合材料的机械性能和监测损伤机制方面的作用提供了有价值的见解。