AN EXPERIMENTAL-STUDY OF THE ANGULAR-DEPENDENCE OF LAMB WAVE EXCITATION AMPLITUDES

The generation of Lamb waves in isotropic layers by phase matching of an obliquely incident, bounded beam is examined experimentally, and th e results compared to theoretical predictions obtained from a simplifi ed model of the process. It is demonstrated experimentally that the ra nge of incident angles over which any given mode can be generated is d ependent upon the size of the transducer used to excite the mode, its frequency content and the pressure distribution across its surface. Ex perimentally obtained excitation amplitude versus incident angle curve s are given for various Lamb wave modes and transducers of different s izes and vibrational characteristics. These experimental amplitudes ar e compared to theoretical curves based on a simplified model of the ge neration process. (C) 1997 Academic Press Limited.