MULTISOURCE EXCITATIONS IN A STRATIFIED BIPHASE STRUCTURE

A stratified biphase structure can have many mechanical resonance mode s due to the existence of several length scales in the system, The res onance effect is greatly enhanced if there are periodic synchronized m ultiple driving sources in the structure. For example, a single beam o r a linear array composite transducers used in medical ultrasonic imag ing. Such resonance behavior can be studied using an extended transfer matrix technique which we name: multisource T-matrix technique. Using this technique we have studied the effects of randomization in a 2-2 composite. It is found that for dispersing the pitch resonance the ran domization of ceramic spacing is more effective for low ceramic conten t, while randomization of ceramic width is mon effective for high cera mic content. (C) 1995 American Institute of Physics.