Efficient Excitation and Detection of Lamb Waves for Process Monitoring and Nde

Lamb waves are currently used in many nondestructive testing applications to determine or monitor elastic properties of plate-like Structures using various excitation methods. The methods vary from point-like dry contact transducers and laser ultrasound techniques in hostile environments to wedge transducers for inspection of excitation of Lamb waves in 2-D geometry by surface immersed structures. In this paper, we analyze the sources, as in the case of many applications. To calculate the coupling characteristics to various Lamb waves, we angular spectrum approach to find the field distributions use the mode orthogonality principle and utilize the on the surface excited by non contact transducers with finite dimensions. We present theoretical results related to Hertzian contact transducers at low frequencies along with some measurements in agreement with theory. We Lamb wave modes in immersion mode. also investigate the wedge transducers exciting different