| Abstract [eng] |
The growing demand for lightweight and fuel-efficient aircraft structures has prioritized the usage of adhesively bonded joints as an alternative to conventional joining techniques such as mechanical fastening and welding. Adhesive bonding offers several advantages, including uniform stress distribution, reduced structural weight, improved stiffness, and high impact resistance. However, the lack of a reliable nondestructive evaluation (NDE) technique capable of accurately assessing bond integrity and detecting interfacial defects remains a major limitation to their wider industrial adoption, particularly in safety-critical sectors such as aerospace and automotive engineering. This study investigates defect characterization in adhesively bonded joints using ultrasonic and radiographic testing, supported by numerical simulations. Two representative defect types, namely inclusions and delaminations, were analyzed to examine their influence on ultrasonic wave propagation and radiographic image contrast. A range of signal-based and image-based features were extracted from both inspection modalities in order to identify parameters most sensitive to flaw presence, size, and geometry. To improve defect detection reliability, data fusion methodologies integrating ultrasonic and radiographic features were developed and implemented. The fusion-based results demonstrated improved defect detectability compared with single methods. The reliability of inspection performance was quantitatively assessed using Model-Assisted Probability of Detection (MAPOD) analysis. Furthermore, the use of custom developed feature extraction, rather than the conventionally used maximum amplitude, significantly improved defect detection capability, highlighting the importance of feature-driven analysis in non-destructive testing and evaluation. |
