Right angle energy harvester

Basic idea: utilize torque to smooth the strain distribution & increase the power density

power density reaches ~80 mW/cm3.

An inevitable gradient of the strain distribution for the traditional cantilever. However, using a torque instead of the force, the strain distribution in the piezoelectric element is made theoretically uniform. Thus, the piezoelectric element generates its maximum output.

The right-angle harvester based on a cantilever with an extended auxiliary part that forms a right angle with the basic part.

The auxiliary part is softer than the main beam. As the low rigidity auxiliary beam lowers the series

resonant frequency of the device and makes the main beam work in a quasi-stationary state, the torque applied at the free end of the main beam smooths out the strain distribution.

Highly uniform strain distribution for the low-stiffness model exists at its resonance frequency

Model I reached its maximum power output at 22.3 Hz, output power was 20.12 mW, power density reaches ~80 mW/cm3.

Publications:

* JW Xu, YB Liu, WW Shao and Z Feng, “Optimization of a right-angle piezoelectric cantilever using auxiliary beams with different stiffness levels for vibration energy harvesting,” Smart Materials and Structures, 21 (6), 2012.

* JW Xu, WW Shao, FR Kong and ZH Feng, “Right-angle piezoelectric cantilever with improved energy harvesting efficiency,” Applied Physics Letters, 96 (15), 2010.

* QC Guan, B Ju, JW Xu, YB Liu and ZH Feng, “Improved strain distribution of cantilever piezoelectric energy harvesting devices using H-shaped proof masses,” Journal of Intelligent Material Systems and Structures, 24 (9), 2013.