Quantitative Structural Health Monitoring by Ultrasonic Guided Waves

摘要

This paper will present a Global-Local (GL) method to simulate the interaction of ultrasonic guided waves with structural detects in plate-like structures. The GL method uses a full Finite Element (FE) discretization of the delected region to properly represent wave diffraction phenomena, and a suitable set of wave functions to simulate regions away from the joint. Displacement and stress continuity conditions are imposed at the boundary between the global and the local regions. The radiated wave Held can be then calculated by using standard techniques (least squares method). The novelty of the proposed approach over previous GL techniques is the use of Semi-Analytical Finite Element (SAFE) modeling for the "global" simulation and the use of this technique to quantify defects In guided waves. The SAFE method, which only requires the discretization of the waveguide's cross-section, allows handling complex structures (e.g. multilayered composites, arbitrary cross-sections, etc.) in a computationally efficient manner. Applications of the GL method to damage quantification will be shown for the cases of notches in aluminum plates and delamination-like defects in aircraft composite panels.