Session: Poster & Student Poster Session

Paper Number: 170348

170348 - Detection of Debonds in Adhesively Bonded Structures Using Quasistatic Components of Nonlinear Guided Waves 

Abstract: 

Multilayer adhesive structures are extensively employed in aerospace, automotive, and civil engineering applications due to their advantages in weight reduction, load transfer efficiency, and structural robustness. However, debonding at adhesive interfaces can critically compromise mechanical performance and potentially lead to structural failure. Therefore, early and reliable detection of such interfacial defects is essential. While conventional linear ultrasonic techniques are widely used for non-destructive evaluation, their sensitivity to debonding is often limited in complex layered systems. Nonlinear ultrasonic methods have emerged as promising alternatives due to their ability to detect subtle damage mechanisms. Most existing research in this field has focused on higher harmonic generation, which can be influenced by both material and instrumentation nonlinearities. In contrast, quasistatic components (QSCs) have recently garnered growing interest due to their unique nonlinear generation mechanism, which originates exclusively from damage-induced nonlinearity, without interference from equipment-related effects. QSCs are also characterized by static-like, low-frequency displacements and low attenuation, making them suitable for long-range defect detection in bonded structures. This study presents a numerical and experimental investigation of QSC-based nonlinear guided wave techniques for detecting debonding in aluminium–epoxy–aluminium multilayer adhesive structures. A three-dimensional finite element model was developed to simulate the generation and propagation of second harmonics and QSCs, incorporating material nonlinearity. For experimental validation, ultrasonic-guided waves were excited in bonded specimens, and the received signals were subsequently collected and analyzed. The results demonstrate the presence of QSCs exclusively in debonded specimens, highlighting their strong correlation with interfacial damage. These findings support the use of QSC-based ultrasonic techniques as a reliable approach for structural health monitoring of bonded assemblies.

Presenting Author: Yongjoon Choi Department of Smart Manufacturing Engineering, Changwon National University

Presenting Author Biography: Yongjoon Choi is a master's student in the Department of Smart Manufacturing Engineering at Changwon National University, South Korea. His research focuses on non-destructive evaluation (NDE), with particular interests in acoustic emission testing and nonlinear guided waves. He has presented his work at national and international conferences, receiving several awards including the Best Poster Presentation Award (1st Place), Best Paper Presentation Award, and an Honorable Mention for Best Oral Presentation. During his undergraduate studies, he received the Capstone Design Excellence Award and the University President’s Award through an overseas research program for major competency enhancement. He also served as president of a student-built vehicle club, demonstrating strong leadership and hands-on engineering experience.

Authors:

Yongjoon Choi Department of Smart Manufacturing Engineering, Changwon National University
Mohammed Aslam Extreme Environment Design and Manufacturing Innovation Center, Changwon National University
Jaesun Lee School of Mechanical Engineering, Changwon National University