| dc.description.abstract | The overall goal of this study was to characterize piezoelectric materials in terms of non-traditional loading, namely tension and ultrasound loading. Compliant Layer Adaptive Composite Stacks (CLACS) consisting of 5 lead zirconate titanate (PZT) disks separated by composite layers were used throughout. Each disk was poled radially (R) or through (T) thickness, to create three types of CLACS: radial-poled (R), through-poled (T), and radial-through-poled (RT) CLACS. CLACS have been designed to harvest maximum power generation at low frequencies of loading. These systems allow for piezoelectric materials to use natural body loading, such as walking, to generate power for bone and soft tissue healing. Compression loading is the most common technique for producing power generation from piezoelectric materials, but in the present study, tension and ultrasound were tested as unconventional modes of loading. In contrast to compression loading, tension loading exhibited little power generation at low frequencies. Tension does not appear to markedly alter the power generated by compression loads, as there was not a significant difference in the power generated by compression before and after tension loading of the T-CLACS and RT-CLACS. However, the R-CLACS under a compression amplitude of 1000N produced statistically significant less power generation than after tension loading. The second unconventional mode of loading examined was ultrasound at the 0̊ orientation relative to the medial axis of the CLACS. Intensities of 0.5\ W/{\rm cm}^2 and 1\ W/{\rm cm}^2 produced power generation between 55 µW to 167 µW. This indicates that ultrasound probably has the capability to enhance bone and soft tissue healing, although ultrasound has a large mean coefficient of variation (66%). Thus, in conclusion, both unconventional loading methods used in this study, namely tension and ultrasound, tend to produce an increase in power generation, however the magnitude of the increase is much less than that observed by compression loading. Overall, this study increases our understanding of the effects of tension and ultrasound on piezoelectric materials. | |
