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To improve piezoelectric harvesting efficiency of Cymbal, optimization design of Cymbal parameters was studied with the method of Taguchi’s orthogonal experiment. The effective factors of piezoelectric harvesting property were firstly analyzed. The orthogonal experiment schedule was then designed. The finite element model of Cymbal was built via ASPL tool in ANSYS software and static analysis was done. The experimental results were gotten with developed program. The optimization level of each factor was gained. Under the synthetical optimization level of each design factor, the piezoelectric analysis was tested and the open voltage of 236.476 V was revealed with improving 35.73% than the maximum voltage of 174.228 V in the orthogonal experiment. The average voltage of 229.98 V was measured with the manufactured optimized Cymbal structure design. The relative error was 2.54% between simulation and measured data. It indicated that the optimization design schedule was reasonable. Cymbal harvester with the optimized parameters could scavenge larger voltage.

The special structural design of piezoelectric Cymbal harvester makes it possess some special characteristics, such as the ease of fabrication and the ability to tailor performance. The comprehensive piezoelectric effects of d_{33} and d_{31} are easily excited for Cymbal harvester under the axial external force [

_{1}, PZT thickness t_{2}, cavity depth h, the dimple diameter d_{1} and the cavity diameter d_{2}. In this paper, the above five geometric factors except D are mainly discussed.

Aluminum is used as the endcap material, PZT -5A is to be piezoelectric ceramics. The diameter of the endcap D is the same as that of the PZT piezoelectric ceramics disk and equal to 29 mm . Based on Taguchi’s orthogonal experiment design, the piezoelectric harvesting characteristic of Cymbal harvester is discussed to find out the above five optimized structural parameters.

The open voltage generated by Cymbal harvester is used as optimization objective, the five above-discussed geometric parameters as factors. The aim of the orthogonal experiment is to optimize the geometric parameters of a Cymbal harvester and to obtain the highest voltage. Meanwhile, an alternative aim is to find out the dominance degrees and the optimal values of these factors.

According to Taguchi parameter design methodology, a

As shown in

Run No. | Factors | Results | ||||
---|---|---|---|---|---|---|

1 (t_{1}/mm) | 2 (t_{2}/mm) | 3 (h/mm) | 4 (d_{1}/mm) | 5 (d_{2}/mm) | Open voltage/V | |

1 | 1 (0.3) | 1 (1) | 1 (1.5) | 1 (4) | 1 (16) | 30.652 |

2 | 1 (0.3) | 2 (2) | 2 (1.6) | 2 (5) | 2 (18) | 58.626 |

3 | 1 (0.3) | 3 (3) | 3 (1.8) | 3 (6) | 3 (20) | 91.838 |

4 | 1 (0.3) | 4 (4) | 4 (2.0) | 4 (8) | 4 (22) | 169.639 |

5 | 2 (0.4) | 1 (1) | 2 (1.6) | 3 (6) | 4 (22) | 117.835 |

6 | 2 (0.4) | 2 (2) | 1 (1.5) | 4 (8) | 3 (20) | 174.228 |

7 | 2 (0.4) | 3 (3) | 4 (2.0) | 1 (4) | 2 (18) | 32.557 |

8 | 2 (0.4) | 4 (4) | 3 (1.8) | 2 (5) | 1 (16) | 41.766 |

9 | 3 (0.5) | 1 (1) | 3 (1.8) | 4 (8) | 2 (18) | 94.535 |

10 | 3 (0.5) | 2 (2) | 4 (2.0) | 3 (6) | 1 (16) | 45.925 |

11 | 3 (0.5) | 3 (3) | 1 (1.5) | 2 (5) | 4 (22) | 97.034 |

12 | 3 (0.5) | 4 (4) | 2 (1.6) | 1 (4) | 3 (20) | 50.936 |

13 | 4 (0.6) | 1 (1) | 4 (2.0) | 2 (5) | 3 (20) | 49.544 |

14 | 4 (0.6) | 2 (2) | 3 (1.8) | 1 (4) | 4 (22) | 50.795 |

15 | 4 (0.6) | 3 (3) | 2 (1.6) | 4 (8) | 1 (16) | 87.227 |

16 | 4 (0.6) | 4 (4) | 1 (1.5) | 3 (6) | 2 (18) | 81.143 |

Sum of level 1:_{ } | 350.755 | 292.566 | 383.057 | 164.94 | 205.57 | |

Sum of level 2: | 366.386 | 329.574 | 314.624 | 246.97 | 266.861 | |

Sum of level 3: | 288.43 | 308.656 | 278.934 | 336.741 | 366.546 | |

Sum of level 4: | 268.709 | 343.484 | 297.665 | 525.629 | 435.303 | |

Average of level 1: | 87.689 | 73.142 | 95.764 | 41.235 | 51.393 | |

Average of level 2: | 91.597 | 82.394 | 78.656 | 61.743 | 66.715 | |

Average of level 3: | 72.108 | 77.164 | 69.734 | 84.185 | 91.637 | |

Average of level 4: | 67.177 | 85.871 | 74.416 | 131.407 | 108.826 | |

Range | 24.42 | 12.729 | 26.03 | 90.172 | 57.433 |

From the results shown in _{1} = 0.4 mm), level 4 of factor 2 (PZT thickness of t_{2} = 4 mm), level 1 of factor 3 (cavity depth of h = 1.5 mm), level 4 of factor 4 (dimple diameter of d_{1} = 8 mm) and level 4 of factor 5 (cavity diameter of d_{2} = 22 mm). Using the above optimized parameters, the open voltage is up to 236.476 V. The optimized result increase 35.73% compared with the maximum value of 174.228 V using the orthogonal experiment in

According to the range value of R, factors in order of dominance degree from big to small list as follows: dimple diameter d_{1}, cavity diameter d_{2}, cavity depth h, endcap thickness t_{1} and PZT thickness t_{2}.

Sample No. | Open voltage(V) | Sample No. | Open voltage(V) |
---|---|---|---|

1 | 230.5 | 6 | 228.8 |

2 | 230.1 | 7 | 229.4 |

3 | 229.6 | 8 | 230.2 |

4 | 230.4 | 9 | 230.4 |

5 | 229.8 | 10 | 230.6 |

To improve the efficiency of Cymbal harvesting energy, Taguchi’s orthogonal experiment design is adopted. The finite element program is developed to simulate the experimental conditions via ANSYS 12.0 two development platforms. Effects of synthetical factors on piezoelectric harvesting efficiency of Cymbal are analyzed. The results show that the dominance degree of each factor lists following: dimple diameter d_{1}, cavity diameter d_{2}, cavity depth h, endcap thickness t_{1} and PZT thickness t_{2}. The excited open voltage of Cymbal with the optimized parameters is larger than the maximum of orthogonal experiment. It indicates that the method of the orthogonal experiment design for optimal Cymbal harvester is available and the optimized structure of Cymbal harvester can be used for savaging higher electrical potential.

The future of work will focus on the application of the optimal Cymbal and coupling with the environment.

This research was supported by the National Natural Science Foundation of China (No. 51175359) and the 4th “333 Engineering” Research Funding Project of Jiangsu Province (BRA2014086).

GuangqingShang,WeiNing,ChunhuaSun, (2015) Cymbal Structural Optimization for Improving Piezoelectric Harvesting Efficiency with Taguchi’s Orthogonal Experiment. Journal of Power and Energy Engineering,03,10-15. doi: 10.4236/jpee.2015.310002