Cymbal harvesters, piezoelectric disk sandwiched between a pair of concaved metal caps

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... circular cymbal, "33" and circular diaphragm mode FEHs. The Flextensional harvesters are known to produce power outputs of at least 1 order of magnitude higher compared to other harvesters types. The Cymbal harvester succeeded in achieving efficiency of 7.8% which was a break through at that time [62]. The circular Cymbal harvesters, as shown in Fig. (1), are formed of a piezoelectric disk sandwiched between a pair of concaved metal caps (domeshaped). This design amplifies the applied force/displacement and, consequently, the electrical charges. Changing the thickness of the metal caps tunes the harvester to give the desired response, the amplification factor (M ) for this frame can be ...

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... where the piezoelectric multi-layer stack is modeled as a mass-spring-damper system as shown in Fig. ...

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... mechanical response of the system to be shown in Fig.(11b) can be written as ...

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... Newton's law on the mass-spring system shown in Fig. 11 we get the ...

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... model the stainless steel (Spring Metal) the FAF is modeled using 3D 10 node tetrahedral Elements SOLID187 (Fig. (12)) which has degrees of freedom limited only to the spatial directions. On the other hand, the piezoelectric stack was modeled using 3D 20-Node Coupled-Field Solid SOLID226 Elements (Fig. (13)). These elements have similar geometry as SOLID186 except that they allow voltage as an additional degree of freedom. The stack is modeled as one ...

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... model the stainless steel (Spring Metal) the FAF is modeled using 3D 10 node tetrahedral Elements SOLID187 (Fig. (12)) which has degrees of freedom limited only to the spatial directions. On the other hand, the piezoelectric stack was modeled using 3D 20-Node Coupled-Field Solid SOLID226 Elements (Fig. (13)). These elements have similar geometry as SOLID186 except that they allow voltage as an additional degree of freedom. The stack is modeled as one piezoelectric piece rather than sets of separate layers of piezoelectric and silver electrodes. This allows using bigger mesh elements and significantly reduces computational ...

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... piezoelectric stack ends were coupled into two master nodes made to connect the resistor element or a capacitance. CIRCU94 element was used for that purpose. Fig. (14) shows the ANSYS commands used to define the resistance as well as some of the boundary conditions. The piezoelectric matrix in ANSYS is different from the Piezoelectric Matrix in the IEEE standards as explained below ...

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... setup of the experiment is shown in Fig. (16). The PM 100 Electrodynamic Vibration Exciterwas (shaker) used; this shaker is capable of producing a force output of 100lbs peak and a maximum displacement of 0.5inch amplitude (peak-peak). The maximum acceleration and frequency this shaker can produce are 100g s and 7000Hz, respectively for an unloaded shaker. ...

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... used. This power amplifier can provide power output of 450W att rms . It can match the performance of the PM 100 shaker when connected for low impedance. There are two ways to control the shaker to perform a sweep motion, either to connect it to a sweep generator (Fig. 19) or to connect it to LABVIEW. The frequency range applied to the shaker was 20 to 300Hz. The problem with using this setup is that when we attempt to apply a sweep function, the shaker output acceleration increases as the frequency increases. Designing a control algorithm to use the acceleration reading as a feedback and then adjusting ...

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... that, the amplification factor for the FAF is 4.6. Fig. (21) shows a plot of the applied force on the stack. The monolithic piezoelectric stack actuator (CeramTech SP505) was used in this study as a harvester instead. The stack is built using 300 piezoelectric layers of 0.1 mm thickness sandwiched between 301 silver electrodes. The total volume of the stack is 7mm × 7mm × 32.40mm, and its ...

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... ANSYS model can be enhanced if the effect of the capacitance of the piezoelectric stack is taken into account. Fig. ( The R ESR in Fig. (31) stands for Equivalent Serial Resistive and is expressed ...

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... explanation for the circuits shown in Fig. (31) and the symbols can be found in Although, the static model is the simplest model, and its equation and coding is extremely trivial it gave an error less than the SDOF and the FEA models. It takes almost no computation cost or time. The error was E rms = 7.7330% which is satisfactory compared to the effort and the complexity of the ...