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Shock and Vibration
Volume 2017, Article ID 8523218, 8 pages
Research Article

Design and Experimental Study of an L Shape Piezoelectric Energy Harvester

1Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
2School of Mechanical Engineering, Hoseo University, Asan 31499, Republic of Korea

Correspondence should be addressed to Seon-Jun Jang; ude.oesoh@elgaewm and Hyung-Jo Jung;

Received 24 April 2017; Revised 26 July 2017; Accepted 12 September 2017; Published 18 October 2017

Academic Editor: Toshiaki Natsuki

Copyright © 2017 In-Ho Kim et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Piezoelectric energy harvesters of cantilevered beam type are studied in various fields due to simplicity. In general, these systems obtain electrical energy from mechanical strain by bending of cantilevered beam. However, conventional systems have disadvantages that they have low efficiency in frequency regions other than resonance frequency. To overcome the limitations, various energy harvesters to apply performance enhancement strategies are proposed and investigated. In this paper, a frequency-changeable L shape energy harvester which is form connected cantilever beam and rigid arm is proposed and investigated. The conventional piezoelectric energy harvester exhibits the principal frequency in the simple bending mode whereas the proposed system features the twisting mode resulting in a higher output voltage than the conventional system. The proposed energy harvester is simplified to a two-degree-of-freedom model and its dynamics are described. How the length of a rigid bar affects its natural frequencies is also studied. To evaluate the performance of the system, experiments by using a vertical shaker and numerical simulation are carried out. As a result, it is shown that the natural frequency for a twisting mode decreases as the arm length increased, and the higher output voltage is generated comparing with those of the conventional energy harvester.