The paper aims to develop improved acoustic-based structural health monitoring (SHM) and\nnondestructive evaluation (NDE) techniques, which provide the waves directivity emitted by the angle\nbeam wedge actuators in thin-walled structures made of plastic materials and polymeric composites.\nOur investigation includes the dispersive analysis of the waves that can be excited in the studied\nplastic panel. Its results allowed to find two kinds of generated acoustic waves-anti-symmetric\nLamb waves (A0) and shear horizontally polarized SH waves (SS0). The bounds of the chosen\nfrequency range for the experimental and numerical studies were accepted as a compromise between\nthe desire to obtain a high defect resolution by generating short waves, their adjustable directivity,\nand maximum propagation length. The finite element model for the transducer was built by using\nthe results of an actuator structure experimental study. The frequency response functions for the\nactuator current and oscillation amplitude of the footprint surface demonstrated good agreement.\nThe found eigenfrequencies of the actuatorâ??s structure were used for the numerical and experimental\nstudy of the Lamb and SH wave generation and propagation in a thin-walled plastic panel. Our\nresults convincingly demonstrated the satisfactory directivity of the actuated waves at their excitation\non the frequencies that corresponded to the natural modes of the actuator oscillation. The authors\nassume that an efficient use of the proposed technique for other analyzed quasi-isotropic materials\nand applied actuators can be provided by preliminary research using a similar approach and methods\npresented in this article.
Loading....