13th International Conference on Fracture June 16–21, 2013, Beijing, China -3- piezoelectric material adopted here is Lead Zirconate Titanate (PZT) ceramics (HAIYING P-51), the major material parameters is shown in Table 2. The enameled copper coil with main parameters shown in Table 3, is wound by using a 40-µm-diameter copper wire (DAYANG WIRE & CABLE) with polyurethane coating. The magnets used here is the sintered rare earth Neodymium Iron Boron (NdFeB) N33 permanent magnet. Its property is listed in Table 4. Table 1. Dimensions of structural components of the proposed vibration energy harvester Component Length (mm) Width (mm) Height (mm) Thickness (mm) 1 60 10 - 0.2 2,4 65 10 14.9 1 3 52 30 24 1 5,6,7,12,13,14 10 5 1 - 8 17 6 2 - 9 10 6 3 - 10 20 17 6 1 11 - - 15 - Table 2. Material property parameters of the employed piezoelectric material Electromechanical coupling factor k31 0.36 k33 0.70 Piezoelectric charge constant (10-12 C/N) d31 -185 d33 400 Relative dielectric constant 11 0 / Tε ε 2400 33 0 / Tε ε 2100 Mechanical quality factor Qm 100 Dielectric dissipation factor (%) tan δ 2.0 Table 3. Parameters of the wound copper coil Number of turns Internal resistance (Ro) (kΩ) Inductance (Lo) (H) ~11000 ~3.9 ~0.3 Table 4. Properties of NdFeB permanent magnet Residual Induction Br (mT) Maximum energy product (BH)max (KJ/m3) Coercive force Hcb (KA/m) 1.13~1.17 247~263 ~836 The resonance frequency of the middle cantilever beam of our VEH prototype is / / 2 cr f k m π = ≈ 11.0 Hz, where m and k, the effective mass and spring constant, are 1.04E-3 kg and 51.7 N/m, respectively. When subjected to external vibration excitation, bending vibration of the middle
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