Metal-Metal and Metal-Composite Material Bondings Characterization Using Guided Lamb Waves
Résumé
The use of structural adhesive bonding becomes prevalent in different industries, due to the numerous advantages that presents compared with mechanical joining techniques. However, the adhesive bonds need tests control before and during their use. There are numerous methods to control the quality of adhesive bonds. Here, we focus on non-destructive methods using ultrasonic guided Lamb waves. The experimental device is a contact emitter transducer which is placed on an inclined PMMA wedge and placed on the bonding structure. A laser is used as a receiver to detect normal displacements at the free surface of the studied structure. These displacements are recorded in the direction of propagation and lead to a matrix of experimental data in the time-position domain. A signal processing is performed to obtain a wave number-frequency representation, or a position-wave number representation. These results are compared with those obtained by solving an interphase numerical model by finite element method. The process is applied to two types of specimens: a metal-composite bond and a metal-metal one. For the metal-composite structure, the purpose is to detect and localize a bonding defect. Using the experimental device previous described on a specimen with a localized defect, we found a criterion to detect and localize the defect. For the metal-metal bond, we have studied four specimens with different grades of adhesion (metal surface treatment, cure rate of the adhesive) and with different plate thicknesses. The purpose is to be able to differentiate between the specimens. Results show that we can differentiate the high grade of adhesion from the others. These results allowed us to characterize the level of adhesion in metal-metal and metal-composite structures. Ongoing studies focus on composite-composite bonding characterization.