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.
Energy Harvest Piezoelectric Effects Cymbal Harvester Taguchi’s Orthogonal Experiment1. Introduction
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 d33 and d31 are easily excited for Cymbal harvester under the axial external force [1] . Besides being used as the actuator and sensor, the piezoelectric Cymbal harvester has recently been focused to be an energy transducer. The harvesting energy properties of Cymbal have been researched via the theoretical analysis method, the finite element method and experiment [2] - [8] . The harvesting energy basic rule and effective factors of Cymbal have been mastered. So basic foundation for applying piezoelectric Cymbal harvester has laid. However, structural optimization and synthetic effect of various factors and the dominance degree of each factor have not been given a clean answer. In this study, the Taguchi experimental design is adopted for studying the synthetic effect of various factors on the output electrical characteristic of piezoelectric Cymbal harvester. The dominance degree of each factor is analyzed according to the result of Taguchi experiment. A optimized structure of Cymbal is determined.
2. Effective Factors of Cymbal Harvester
Figure 1 shows the structure of piezoelectric ceramics Cymbal harvester. The factors of a Cymbal harvester on the piezoelectric harvesting characteristics deal with two kinds: physical and geometrical ones. The physical factors include the materials of endcap, piezoelectric ceramic and binder, while the geometrical factors involve the endcap diameter D, endcap thickness t1, PZT thickness t2, cavity depth h, the dimple diameter d1 and the cavity diameter d2. 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.
3. The Taguchi’s Orthogonal Experiment Design
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 standard orthogonal array with five factors in four levels each in 16 runs is employed [9] . The considering the five above-discussed parameters are shown in Table 1. Each row of the orthogonal array represents a specified set of factor levels to be tested.
4. The Finite Element Analysis
As shown in Table 1, 16 experiments need to run for obtaining the open voltage according to the orthogonal experiment design. For saving time, manpower, material and financial resources, the finite element method is adopted. The technologies of APDL parametric modeling and command stream are used to develop the application program for Cymbal piezoelectric analysis based on two development platform of ANSYS 12.0. The developed primary menu, dialogue of inputting parameters and the finite element model are shown in Figures 2-4, respectively.
Cymbal structural parameters
Schedule and results of Taguchi’s orthogonal experiments
Run No.
Factors
Results
1 (t1/mm)
2 (t2/mm)
3 (h/mm)
4 (d1/mm)
5 (d2/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: (V)
87.689
73.142
95.764
41.235
51.393
Average of level 2: (V)
91.597
82.394
78.656
61.743
66.715
Average of level 3: (V)
72.108
77.164
69.734
84.185
91.637
Average of level 4: (V)
67.177
85.871
74.416
131.407
108.826
Range (V)
24.42
12.729
26.03
90.172
57.433
The developed main menu
Dialogue of input parameters
Cymbal finite element model
Table 1 lists the simulation results calculated by using the developed program. Meanwhile, Table 1 is also shown the average and range of each level of factors.
5. Analysis of Simulation Results
From the results shown in Table 1, it can be seen that the maximum voltage of 174.228 V is obtained under the parametric conditions of No. 6. However, from the average of each factor in four levels, the optimized parameters are: level 2 of factor 1 (endcap thickness of t1 = 0.4 mm), level 4 of factor 2 (PZT thickness of t2 = 4 mm), level 1 of factor 3 (cavity depth of h = 1.5 mm), level 4 of factor 4 (dimple diameter of d1 = 8 mm) and level 4 of factor 5 (cavity diameter of d2 = 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 Table 1. Figure 5 shows the potential distribution under the optimized conditions.
According to the range value of R, factors in order of dominance degree from big to small list as follows: dimple diameter d1, cavity diameter d2, cavity depth h, endcap thickness t1 and PZT thickness t2.
6. Test Measurement
Figure 6 shows the manufactured samples according to the optimized parameters of Cymbal. During measuring, the material test system is used as the loading equipment, Tektronix oscilloscope is adopted to collect electric signal. The test results are shown in Table 2. The average of test results is 229.98 V while data processing. Compared to the simulation result of 236.476 V, the absolute error is 2.54%. The error mainly comes from the following: 1) without considering effect of binder during simulation; 2) material difference between simulation and test. It shows that the simulation and test fits well and Taguchi’s orthogonal experiment design is available for optimizing Cymbal structure.
Voltage distribution with optimized parameters
Cymbal samples with optimized parameters
The measured voltage data
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
7. Conclusions
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 d1, cavity diameter d2, cavity depth h, endcap thickness t1 and PZT thickness t2. 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.
Acknowledgements
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).
Cite this paper
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
NOTESReferencesKim, H.W., Priya, S., Uchino, K. and Robert, E. (2005) Piezoelectric Energy Harvesting under High Pre-Stressed Cyclic Vibrations. Journal of Electroceramics, 15, 27-34. </br>http://dx.doi.org/10.1007/s10832-005-0897-zPan, Z.M. and Liu, B. (2006) Mathematical Model of Cymbal-Type Piezoelectric Transducers. China Mechanical Engineering, 17, 283-286.Guo, Z.Y., Ye, M., Cheng, B., Bai, Z.F. and Cao, B.G. (2007) Influence of Shape Parameters on Electricity Generation by Cymbal Transducer. Mechanical Science and Technology, 26, 1454-1457.Lu, Y.G. and Yan, Z.F. (2013) Finite Element Analysis on Energy Harvesting with Cymbal Transducer. Journal of Vibration and Shock, 32, 157-162.Sun, C.H., Shang, G.Q. and Yu, J. (2011) FEM Analysis of Cymbal Transducer for Electricity Generation. Mechanical Science and Technology, 30, 138-141.Ochoa, P., Pons, J.L., Villegas, M. and Fernandez, J.F. (2005) Mechanical Stress and Electric Potential in Cymbal Piezoceramics by FEA. Journal of the European Ceramic Society, 25, 2457-2461.</br>http://dx.doi.org/10.1016/j.jeurceramsoc.2005.03.082Xing, Z.B., Sun, C.L., Liu, G.G. and Zhao, X.Z. (2007) An Experimental Study of Cymbal Transducers. Piezoelectrics & Acoustooptics, 29, 273-275.Wu, L., Chure, M.-C., Wu, K.-K. and Tung, C.-C. (2014) Voltage Generated Characteristics of Piezoelectric Ceramics Cymbal Transducer. Journal of Materials Science and Chemical Engineering, 2, 32-37.</br>http://dx.doi.org/10.4236/msce.2014.210005Zhao, X.M. (2006) Experimental Design Methods. Science Press, Beijing.