Array transducers based on 2-2 piezocomposites

The trade-off between sensitivity and bandwidth in ultrasonic transducers devoted to NDT purposes is sometimes unbalanced in favour of sensitivity, due to the attenuation of the materials and structures to be inspected. Array transducers have been scarcely used in NDT due to standards' constraints. To improve the bandwidth of the transducers without lowering the sensitivity, a piezoelectric composite multifrequency approach has been used. The single array element is composed of the parallel connection of piezoelectric bars with the same thickness but different width. A model which takes into account the propagation through both the thickness and width directions in isotropic and piezoelectric materials, has been used to optimize the geometry of single transducer element. The increase of the bandwidth can be as much as 50% with the same, at least, high sensitivity.