Abstract

Using adhesively bonded composite patch repairs has been increased in various industries to improve the structural integrity of cracked metallic structures in recent decades. Monitoring of crack propagation and composite patch debonding, as two dominant failure mechanisms in this repair technique, plays a significant role in the integrity assessment of the component. This research conducts an experimental investigation on the simultaneous monitoring of these two failure mechanisms in a cracked metallic specimen repaired by a composite patch. For this purpose, the electromechanical impedance method was used to evaluate the feasibility of recognizing the type of damage at any phase of total damage propagation process. Two piezoelectric sensors were implemented, one mounted on the metal and the other on the composite patch. Investigation of impedance spectrums and damage index trends showed that debonding and crack propagation produce different effects on the measurements made by sensors. These differences were used as a basis of identifying the type of damage. As a result, some features were introduced to classify the type of damage in each step of damage propagation.

中文翻译：

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复合补丁修复的裂纹金属试样中基于EMI的损伤类型识别研究

摘要

近几十年来，在各个行业中已经增加了使用粘合复合材料补片修补的方法，以改善破裂金属结构的结构完整性。作为这种修复技术中的两个主要失效机制，对裂纹扩展和复合材料修补剂脱粘的监测在部件的完整性评估中起着重要作用。这项研究进行了一项实验研究，以同时监测由复合贴片修复的破裂金属试样中的这两种破坏机理。为此目的，使用机电阻抗方法评估在总损害传播过程的任何阶段识别损害类型的可行性。实现了两个压电传感器，一个安装在金属上，另一个安装在复合贴片上。对阻抗谱和损伤指数趋势的研究表明，脱粘和裂纹扩展对传感器的测量产生不同的影响。这些差异被用作识别损害类型的基础。结果，引入了一些功能以对损坏传播的每个步骤中的损坏类型进行分类。