13th International Conference on Fracture June 16–21, 2013, Beijing, China -2- flux change in the coil to generate AC voltage. A prototype has been designed, fabricated, tested and analyzed. 2. Structure and Principle As shown in Fig. 1(a), the proposed VEH is generally comprised of three parts, i.e., the top and bottom frames, the middle cantilever beam, and the side frames. The frames are made of stainless steel, and the cantilever beam is made of phosphor bronze. Four piezoelectric modules (PZT-T-EX, PZT-T-IN, PZT-B-EX, and PZT-B-IN), each with five identical piezoelectric plates connected in parallel electrically, and two single piezoelectric plates (PZT-T-IMP and PZT-B-IMP) are bonded to the top and bottom frames. Two pairs of permanent magnets are anti-symmetrically bonded onto the side frames. A coil housing with a hand-wound enameled copper coil and impact body is attached to the tip of the middle cantilever beam, and acts as a proof mass. The coil housing is used to accommodate and fix the coil relative to the cantilever beam. The distance between the impact body and the impacted piezoelectric plates (PZT-T-IMP and PZT-B-IMP) is about 4.5 mm. The VEH could be mounted on a vibrating source for power generation. In our experiments, it is bolted on an electric shaker, as shown in Fig. 1(b). 5. PZT-T-IN 6. PZT-T-EX 4. Top frame 1. Cantilever beam 7. PZT-T-IMP 8. Impact body 9. Permanent Magnets 10. Coil housing 11. Coil 14. PZT-B-IN 13. PZT-B-EX 12. PZT-B-IMP 2. Bottom frame 3. Side frame Bolt Mounting fixture Vibration energy harvester Figure 1. Harvester structure including (a) isometric section view of the proposed VEH structure and (b) photograph of the fabricated VEH prototype mounting on an electric shaker. The detailed dimensions of structural components of the VEH prototype are listed in Table 1. The (a) (b)
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