Small and lightweight structures have very high natural frequencies and small elastic displacement compared to ordinary structures. Due to limited excitation bandwidth and relatively large size of pick up devices, conventional modal testing facilities are not feasible for testing MEMS structures. A modal testing system based on the base excitation principle was developed in this research. In the meantime, the associated mathematical model for frequency response functions was derived as well. Testing structures are mounted on a rigid platform that can move essentially with only one translational degree of freedom. An electric discharge pulse strikes the platform to provide a very wide band excitation. Laser Doppler vibrometers are used to pick up both input and output signals. Since these signals are picked up without contacting structures, the structural dynamic characteristics remain intact without any distortion. With this system, modal parameters of a miniature structure can be extracted, and the receptance functions are synthesized successfully.

Issue Section:
Technical Papers
Keywords:
micromechanical devices, vibration measurement, vibrations, dynamic testing, measurement by laser beam
Topics:
Excitation, Testing, Frequency response, Displacement, Electric discharge, Laser Doppler vibrometers
1.
Unholtz, K., 1988, “Vibration Testing Machines,” Shock and Vibration Handbook, 3rd ed., C. M. Harris, ed., McGraw-Hill, New York, Chap. 25.
2.
Broch, J. T., 1980, Mechanical Vibration and Shock Measurements, 2nd ed., Bru¨el & Kjær, Nærum, Denmark.
3.
Patton, M. E., and Trethwey, M. W., 1987, “A Technique for Nonintrusive Modal Analysis of Ultralightweight Structures,” Proc. of 5th International Modal Analysis Conference, pp. 1425–1431.
4.
Wilson
,
C. J.
, and
Bogy
,
D. B.
,
1994
, “
Experimental Modal Analysis of a Suspension Assembly Loaded on a Rotating Disk
,”
ASME J. Vibr. Acoust.
,
116
,
1
,pp.
85
–
92
.
5.
Wilson
,
C. J.
, and
Bogy
,
D. B.
,
1994
, “
Modal Analysis of a Suspension Assembly
,”
ASME J. Eng. Ind.
,
116
,
3
, pp.
377
–
386
.
6.
Wilson
,
C. J.
, and
Bogy
,
D. B.
,
1996
, “
An Experimental Modal Analysis Technique for Miniature Structures
,”
ASME J. Vibr. Acoust.
,
118
,
1
, pp.
1
–
9
.
7.
Miu
,
D. K.
,
Frees
,
G. M.
, and
Gompertz
,
R. S.
,
1990
, “
Experimental and Numerical Analysis of Read/Write Head Suspension Dynamics for High-Performance Floppy Drive System
,”
ASME J. Vibr. Acoust.
,
112
,
1
, pp.
26
–
32
.
8.
Miu
,
D. K.
,
Frees
,
G. M.
, and
Gompertz
,
R. S.
,
1990
, “
Tracking Dynamics of Read/Write Head Suspensions in High-Performance Small Form Factor Rigid Disk Drives
,”
ASME J. Vibr. Acoust.
,
112
,
1
, pp.
33
–
39
.
9.
Zhang, P. Q., Huang, T. C., Tang, X. L., Wang, Q. M., and Yan, H. W., 1993, “Vibration Analysis of a Miniature Silicon Resonating Beam Force Sensor,” Proc. of 11th International Modal Analysis Conference, pp. 972–979.
10.
Lee, J. C., and Chou, Y. F., 1991, “Driven-Base Modal Parameter Estimation for Continuous Structures,” Proc. of 9th International Modal Analysis Conference, pp. 789–796.
11.
Chen, J. S., Su, C. P., and Chou, Y. F., 1995, “Modal Analysis of Miniature Structures,” Proc. of 13th International Modal Analysis Conference, pp. 969–975.
12.
Chou, Y. F., 1987, “Modal Testing Theory for Continuous Systems,” Proc. of 5th International Modal Analysis Conference, pp. 650–654.
13.
Raether, H., 1964, Electron Avalanches and Breakdown in Gases, Butterworths, London.
Copyright © 2001
 by ASME
You do not currently have access to this content.