An improved technique for sensing damage initiation and progression in thermoplastic resin composite plate specimens is presented in this study. The composite plate specimens are investigated by using a nonlinear ultrasonic (NLU) technique called Sideband Peak Count Index or SPC-I. The technique presented in this paper is an improvement from the previous SPC-I technique. This improved technique provides more reliable and consistent results and can monitor the damage progression over a wide range. In this paper the narrow band SPC-I technique is introduced to replace the conventional wide band SPC-I technique. The method implemented here is improved in three ways. First and foremost the narrow band SPC-I technique is introduced. Secondly, the non-permanently adhered gel coupled Lead-Zirconate-Titanate (PZT) transducers are used to reduce inconsistency in transducer adhesion and manufacturing. Lastly, higher sampling rate equipment is used for better signal resolution and peak counting. The experiments are performed on 4 sets of composite plate specimens fabricated using two composite fiber materials (Glass and Basalt) that have increasing levels of damage. The composite plate specimens were damaged by a falling weight impact machine with increasing impact energy (0 J, 10 J, 20 J and 30 J). The composite plate specimens were examined by propagating a narrow band chirp signal through the specimens using gel coupled transducers in a transmission mode setup. The received signals were recorded and analyzed using the NLU SPC-I technique. The modified SPC-I technique proposed in this paper can reliably and consistently detect both initiation and progression of damage in the composite plate specimens.

本研究介绍了一种用于感测热塑性树脂复合板试样中损坏开始和进展的改进技术。复合板试样是通过使用被称为非线性超声（NLU）技术研究小号ideband P EAK Ç 'mount我索引或 SPC-I。本文介绍的技术是对先前 SPC-I 技术的改进。这种改进的技术提供了更可靠和一致的结果，并且可以在很宽的范围内监测损伤进展。本文介绍了窄带 SPC-I 技术来替代传统的宽带 SPC-I 技术。这里实现的方法从三个方面进行了改进。首先介绍窄带 SPC-I 技术。其次，非永久性粘附凝胶耦合的锆钛酸铅 (PZT) 换能器用于减少换能器粘附和制造的不一致性。最后，更高的采样率设备用于更好的信号分辨率和峰值计数。这些实验是在 4 组复合板试样上进行的，这些试样是使用两种复合纤维材料（玻璃和玄武岩）制成的，这些材料具有越来越高的损伤水平。随着冲击能量的增加（0 J、10 J、20 J和30 J），复合板试样被落锤冲击机损坏。通过在传输模式设置中使用凝胶耦合换能器通过样本传播窄带啁啾信号来检查复合板样本。使用 NLU SPC-I 技术记录和分析接收到的信号。本文提出的改进的 SPC-I 技术可以可靠且一致地检测复合板试样中损伤的开始和进展。随着冲击能量的增加（0 J、10 J、20 J和30 J），复合板试样被落锤冲击机损坏。通过在传输模式设置中使用凝胶耦合换能器通过样本传播窄带啁啾信号来检查复合板样本。使用 NLU SPC-I 技术记录和分析接收到的信号。本文提出的改进的 SPC-I 技术可以可靠且一致地检测复合板试样中损伤的开始和进展。随着冲击能量的增加（0 J、10 J、20 J和30 J），复合板试样被落锤冲击机损坏。通过在传输模式设置中使用凝胶耦合换能器通过样本传播窄带啁啾信号来检查复合板样本。使用 NLU SPC-I 技术记录和分析接收到的信号。本文提出的改进的 SPC-I 技术可以可靠且一致地检测复合板试样中损伤的开始和进展。