**Piezoelectric Impedance-Based Non-Destructive Testing Method for Possible Identification of Composite Debonding Depth**

#### **Wongi S. Na 1,\* and Jongdae Baek 2**


Received: 3 August 2019; Accepted: 16 September 2019; Published: 17 September 2019

**Abstract:** Detecting the depth and size of debonding in composite structures is essential for assessing structural safety as it can weaken the structure possibly leading to a failure. As composite materials are used in various fields up to date including aircrafts and bridges, inspections are carried out to maintain structural integrity. Although many inspection methods exist for detection damage of composites, most of the techniques require trained experts or a large equipment that can be time consuming. In this study, the possibility of using the piezoelectric material-based non-destructive method known as the electromechanical impedance (EMI) technique is used to identify the depth of debonding damage of glass epoxy laminates. Laminates with various thicknesses were prepared and tested to seek for the possibility of using the EMI technique for identifying the depth of debonding. Results show promising outcome for bringing the EMI technique a step closer for commercialization.

**Keywords:** debonding; non-destructive testing; piezoelectric; electromechanical impedance; damage detection; impedance-based technique; damage depth
