Multilayer 1-3 piezocomposites - Theoretical and experimental study of pillar misalignment

The use of multilayer piezoelectric ceramic and 2-2 connectivity composites in ultrasonic transducers has been widely reported. However, multilayer 1-3 piezocomposites have not yet been very well documented and issues such as pillar misalignment remain to be fully explored. This paper reports an investigation of such misalignment carried out with the PZ Flex finite element analysis package. A suite of 2D, 2.5D and 3D models was set up, utilising different symmetry constraints. These clarified theoretically how various thickness and lateral modes were generated, including some requiring full 3D analysis. The results were compared with prototypes with correctly aligned and fully misaligned pillars. They showed reasonable correspondence and allowed us to estimate acceptable pillar alignment more effectively than with other results in the literature.