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Research Papers

Piezoelectric T-Beam Actuators

[+] Author and Article Information
Hareesh K. R. Kommepalli

Department of Mechanical and Nuclear Engineering,  The Pennsylvania State University, University Park, PA 16802 e-mail: kommepal@gmail.com

Kiron Mateti

Department of Electrical Engineering,  The Pennsylvania State University, University Park, PA 16802 e-mail: kxm446@psu.edu

Christopher D. Rahn1

Department of Mechanical and Nuclear Engineering,  The Pennsylvania State University, University Park, PA 16802 e-mail: cdrahn@psu.edu

Srinivas A. Tadigadapa

Department of Electrical Engineering,  The Pennsylvania State University, University Park, PA 16802 e-mail: sat10@psu.edu

1

Corresponding author.

J. Mech. Des 133(6), 061003 (Jun 15, 2011) (9 pages) doi:10.1115/1.4004002 History: Received May 19, 2010; Revised April 09, 2011; Published June 15, 2011; Online June 15, 2011

This paper develops models, fabricates, experimentally tests, and optimizes a novel piezoelectric T-beam actuator. With a T-shaped cross-section, and bottom and top flanges and web electrodes, a cantilevered beam can bend in both in-plane and out-of-plane directions upon actuation. Analytical models predict the tip displacement and blocking force in both directions. Six mesoscale T-beam prototypes are monolithically fabricated by machining and microfabrication techniques and experimentally tested for in-plane and out-of-plane displacements and out-of-plane blocking force. The analytical models closely predict the T-beam displacement and blocking force performance. A nondimensional analytical model predicts that all T-beam designs for both in-plane and out-of-plane actuations, regardless of scale, have nondimensional displacement and blocking force equal to nondimensional voltage. Another form of nondimensional model optimizes the T-beam cross-section for maximum performance. Optimization study shows that a cross-section with width ratio, b*, and thickness ratio, t*, approaching zero produces maximum displacement, b*=t*=0.381 produces maximum blocking force, and b*0.25, t*0.33 produces maximum mechanical energy.

Copyright © 2011 by American Society of Mechanical Engineers
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References

Figures

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Figure 4

Photograph of a fabricated and mounted T-beam (Device 4) actuator

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Figure 5

Photograph of experimental set-up to measure displacement and blocking force of T-beam actuators

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Figure 6

Free tip out-of-plane displacement wf versus applied electric field ϕ versus for Device 3: theoretical (solid — web actuation, dashed — flange actuation, dashdot — right or left flange actuation) and experimental (star — web actuation, diamond — flange actuation, square — left flange, and triangle — right flange)

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Figure 7

In-plane tip displacement, vf versus applied electric field, ϕ for Device 3: theoretical (dashdot—right flange (top), left flange (bottom)) and experimental (plus—left flange, circle—right flange)

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Figure 8

Tip blocking force, F3b versus applied electric field ϕ for Device 3: theoretical (solid—web actuation, dashed—flange actuation) and experimental (star—web actuation, diamond—flange actuation)

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Figure 11

Contour plot of nondimensional displacement (Kw)flange versus nondimensional web width b* and thickness t* for PZT-4 material properties (Table 4)

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Figure 12

Nondimensional displacement Kw versus nondimensional flange thickness t* for b* = 0.381 with PZT-4 material properties for web (theoretical—solid, experimental—star) and flange (theoretical—dashed, experimental—diamond) actuation

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Figure 13

Nondimensional blocking force KF versus nondimensional web width b* and thickness t*

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Figure 14

Nondimensional blocking force KF versus nondimensional flange thickness t* for b* = 0.381 for web (theoretical—solid and experimental—star) and flange (theoretical—dashed and experimental—diamond) actuation

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Figure 15

Nondimensional energy parameter KE versus nondimensional web width b*, and thickness t*

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Figure 16

Nondimensional mechanical energy KE versus nondimensional flange thickness t* for b* = 0.381 (theoretical—black solid (web actuation) and black dashed (flange actuation), experimental—star (web actuation) and diamond (flange actuation)) and b* = 0.25 (cyan)

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Figure 3

Schematic illustration of T-beam fabrication: (a) start with 1 mm thick bulk PZT-4 with Cr/Au coating, (b) dice to form web regions, (c) etch bottom electrodes, (d) spray photoresist pattern and evaporate Cr/Au for flange electrodes, (e) lift-off photoresist to form flange electrodes, and (f) release individual T-beams by dicing

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Figure 2

T-beam model: (a) the initial and deflected shape (out-of-plane (top) and in-plane (bottom)) and (b) cross section

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Figure 1

T-beam actuator concept: (a) as fabricated and deflected shapes when voltage is applied between (b) both flanges and bottom electrodes, (c) web and bottom electrode, (d) left flange and bottom electrode, and (e) right flange and bottom electrode

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Figure 9

Nondimensional free tip displacements, vf*, wf* versus nondimensional voltages, V2*, V3* for devices 1 (blue), 2 (red), 3 (black), 4 (magenta), 5 (green), and 6 (cyan): Theoretical (solid) and experimental (web actuation (*), flange actuation(♦), left flange (□ or +), right flange actuation (△ or ○))

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Figure 10

Nondimensional blocking force F3b* versus nondimensional voltage V3* for devices 1 (blue), 2 (red), 3 (black), 4 (magenta), 5 (green), and 6 (cyan): Theoretical (solid) and experimental (web actuation (*), flange actuation (♦), left flange (□ or +), right flange actuation (△ or ○))

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