A NEW VIBRATION MODE IN TALL, NARROW

A new vibration mode of a tall narrow element in an acoustic array has been discovered and is presented here. This mode is typically lower in frequency than the main desired thickness mode, so it has come to be designated the low frequency mode. .It is of high Q and is strongly excited in arrays made of PZT ceramics. Both experimental data and a theoretical model will be presented. used for acoustical imaging. Mode suppression techniques will be discussed. Experimental resul ts will be presented. This mode has a detrimental effect in arrays