Numerical Determination of Weak Adhesive Bonds Using Ultrasonic Guided Waves

Egidijus Žukauskas^1,*, Damira Smagulova¹, Elena Jasiūnienė^1,2
1 Prof. K. Baršauskas Ultrasound Research Institute, Kaunas University of Technology, K. Baršausko St. 59, Kaunas, Lithuania
2 Department of Electronics Engineering, Kaunas University of Technology, Studentų St. 50, Kaunas, Lithuania
* Corresponding Author: Egidijus Žukauskas. Email: email
(This article belongs to the Special Issue: Advances in Numerical Modeling of Composite Structures and Repairs)

Computer Modeling in Engineering & Sciences https://doi.org/10.32604/cmes.2026.077492

Received 10 December 2025; Accepted 09 February 2026; Published online 24 February 2026

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Abstract

Adhesively bonded joints are widely used in modern lightweight structures due to their high strength-to-weight ratio and design flexibility. However, the reliable non-destructive evaluation of bond integrity remains a significant challenge. This study presents a numerical investigation of adhesively bonded joints with different adhesive properties using ultrasonic guided waves. The main focus of the investigation is to evaluate the feasibility of using guided waves to assess bond integrity, particularly for detecting challenging weak bonds. For this purpose, a theoretical analysis of dispersion curves was conducted, revealing that the S0 Lamb wave mode is significantly sensitive to variations in adhesive properties in the 300–700 kHz frequency range. Finite element modelling was used to analyse the propagation of guided waves in two scenarios: an adhesively bonded aluminum structure and a more complex configuration– adhesively bonded lap joints. The Short-Time Fourier Transform (STFT) was used to process the obtained results and determine the group velocities of guided waves. By analysing the group velocity characteristics, their dependence on the adhesive properties was identified. In the first scenario, a clear separation of S0 modes from A0 modes was observed in the STFT analysis, with a decrease in group velocity as adhesive stiffness increased. For the more complex lap joint scenario, the separation between A0 and S0 modes was less distinct. However, the analysis of the average group velocity shows a dependence of average group velocity on adhesive properties. This is similar to the first scenario. There is a decrease in average group velocity as adhesive stiffness increases. The results obtained demonstrate that guided wave-based methods have a high potential for non-destructive evaluation of adhesively bonded structures, including the detection of weak bonds.