This work presents the experimental evaluation of the state-variable modal decomposition method for a modal parameter estimation of multidegree-of-freedom and continuous vibration systems. Using output response ensembles only, the generalized eigenvalue problem is formed to estimate eigenfrequencies and modal vectors for a lightly damped linear clamped-free experimental beam. The estimated frequencies and modal vectors are compared against the theoretical system frequencies and modal vectors. Satisfactory results are obtained for estimating both system frequencies and modal vectors for the first five modes. To validate the actual modes from the spurious ones, modal coordinates are employed, which, together with frequency and vector estimates, substantiate the true modes. This paper also addresses the error associated with estimation when the number of sensors is less than the active/dominant modes of the system shown via a numerical example.

References

1.
Ibrahim
,
S. R.
, and
Mikulcik
,
E. C.
, 1977, “
A Method for the Direct Identification of Vibration Parameters From the Free Response
,”
Shock and Vibration Bulletin
,
47
(
4
), pp.
183
198
.
2.
Vold
,
H.
,
Kundrat
,
J.
,
Rocklin
,
G.
, and
Russel
,
R.
, 1982, “
A Multi-Input Modal Estimation Algorithm for Mini-Computer
,”
SAE Tech. Pap. Ser.
,
91
, pp.
815
821
.
3.
Juang
,
J.-N.
, and
Pappa
,
R. S.
, 1985, “
An Eigensystem Realization Algorithm for Modal Parameter Identification and Model Reduction
,”
J. Guid. Control Dyn.
,
8
(
5
), pp.
620
627
.
4.
Brown
,
D. L.
,
Allemang
,
R. J.
,
Zimmerman
,
R. D.
, and
Mergeay
,
M.
, 1979, “
Parameter Estimation Techniques for Modal Analysis
,”
SAE Trans.
,
88
, pp.
828
846
.
5.
Overschee
,
P. V.
, and
De Moor
,
B.
, 1996,
Subspace Identification for Linear Systems: Theory-Implementation-Applications
,
Kluwer Academic
,
Boston, MA
.
6.
Vold
,
H.
, 1986, “
Orthogonal Polynomials in the Polyreference Method
,”
Proceedings of the International Seminar on Modal Analysis
,
Katholieke University of Leuven
,
Belgium
.
7.
Richardson
,
M.
, and
Formenti
,
D. L.
, 1982, “
Parameter Estimation From Frequency Response Measurements Using Rational Fraction Polynomials
,”
Proceedings of the International Modal Analysis Conference
, pp.
167
182
.
8.
Shih
,
C. Y.
,
Tsuei
,
Y. G.
,
Allemang
,
R. J.
, and
Brown
,
D. L.
, 1988, “
Complex Mode Indication Function and Its Application to Spatial Domain Parameter Estimation
,”
Mech. Syst. Signal Process.
,
2
, pp.
367
377
.
9.
Brincker
,
R.
,
Zhang
,
L.
, and
Andersen
,
P.
, 2001, “
Modal Identification of Output-Only Systems Using Frequency Domain Decomposition
,”
Smart Mater. Struct.
,
10
, pp.
441
445
.
10.
Liu
,
W.
,
Gao
,
W. C.
, and
Sun
,
Y.
, 2009, “
Application of Modal Identification Methods to Spatial Structure Using Field Measurement Data
,”
ASME J. Vibr. Acoust.
,
131
(
3
), p.
034503
.
11.
Juang
,
J.-N.
, and
Phan
,
M. Q.
, 2001,
Identification and Control of Mechanical Systems
,
Cambridge University Press
,
New York
.
12.
Ewins
,
D. J.
, 1984,
Modal Testing: Theory and Practice
,
Research Studies
,
Letchworth, UK
.
13.
Braun
,
S.
, and
Ram
,
Y. M.
, 1987, “
Determination of Structural Modes via the Prony Model: System Order and Noise Induced Poles
,”
J. Acoust. Soc. Am.
,
81
(
5
), pp.
1447
1459
.
14.
Arruda
,
J. R. F.
,
Campos
,
J. P.
, and
Pivab
,
J. I.
, 1996, “
Experimental Determination of Flexural Power Flow in Beams Using a Modified Prony Method
,”
J. Sound Vib.
,
197
(
3
), pp.
309
328
.
15.
Kerschen
,
G.
,
Poncelet
,
F.
, and
Golinval
,
J. C.
, 2007, “
Physical Interpretation of Independent Component Analysis in Structural Dynamics
,”
Mech. Syst. Signal Process.
,
21
(
4
), pp.
1561
1575
.
16.
Poncelet
,
F.
,
Kerschen
,
G.
,
Golinval
,
J. C.
, and
Verhelst
,
D.
, 2007, “
Output-Only Modal Analysis Using Blind Source Separation Techniques
,”
Mech. Syst. Signal Process.
,
21
, pp.
2335
2358
.
17.
Chelidze
,
D.
, and
Zhou
,
W.
, 2006, “
Smooth Orthogonal Decomposition-Based Vibration Mode Identification
,”
J. Sound Vib.
,
292
, pp.
461
473
.
18.
Zhou
,
W.
, and
Chelidze
,
D.
, 2008, “
Generalized Eigenvalue Decomposition in Time Domain Modal Parameter Identification
,”
ASME J. Vibr. Acoust.
,
130
(
1
), p.
011001
.
19.
Farooq
,
U.
, and
Feeny
,
B. F.
, 2008, “
Smooth Orthogonal Decomposition for Randomly Excited Systems
,”
J. Sound Vib.
,
316
(
1–5
), pp.
137
146
.
20.
Feeny
,
B. F.
, and
Farooq
,
U.
, 2008, “
A Nonsymmetric State-Variable Decomposition for Modal Analysis
,”
J. Sound Vib.
,
310
(
4–5
), pp.
792
800
.
21.
Feeny
,
B. F.
, and
Farooq
,
U.
, 2007, “
A State-Variable Decomposition Method for Estimating Modal Parameters
,”
ASME International Design Engineering Technical Conferences
.
22.
Feeny
,
B.
, and
Kappagantu
,
R.
, 1998, “
On the Physical Interpretation of Proper Orthogonal Modes in Vibrations
,”
J. Sound Vib.
,
211
(
4
), pp.
607
616
.
23.
Feeny
,
B. F.
, 2002, “
On the Proper Orthogonal Modes and Normal Modes of Continuous Vibration Systems
,”
ASME J. Vibr. Acoust.
,
124
(
1
), pp.
157
160
.
24.
Han
,
S.
, and
Feeny
,
B. F.
, 2003, “
Application of Proper Orthogonal Decomposition to Structural Vibration Analysis
,”
Mech. Syst. Signal Process.
,
17
(
5
), pp.
989
1001
.
25.
Kerschen
,
G.
, and
Golinval
,
J. C.
, 2002, “
Physical Interpretation of the Proper Orthogonal Modes Using the Singular Value Decomposition
,”
J. Sound Vib.
,
249
(
5
), pp.
849
865
.
26.
Feeny
,
B. F.
, and
Liang
,
Y.
, 2003, “
Interpreting Proper Orthogonal Modes in Randomly Excited Vibration Systems
,”
J. Sound Vib.
,
265
(
5
), pp.
953
966
.
27.
Shanmugan
,
K. S.
and
Breipohl
,
A. M.
, 1988,
Random Signals: Detection, Estimation and Data Analysis
,
Wiley
,
New York
.
28.
Bendat
,
J. S.
, and
Piersol
,
A. G.
, 1986,
Random Data: Analysis and Measurement Procedures
, 2nd ed.,
Wiley
,
New York
.
29.
McConnell
,
K.
, 1995,
Vibration Testing: Theory and Practice
,
Wiley
,
New York
.
30.
Kailath
,
T.
, 1980,
Linear Systems
,
Prentice-Hall
,
Englewood Cliffs, NJ
.
31.
Rugh
,
W. J.
, 1995,
Linear System Theory
, 2nd ed.,
Prentice-Hall
,
Englewood Cliffs, NJ
.
32.
Chen
,
C.-T.
, 1998,
Linear System Theory and Design
, 3rd ed.,
Oxford University Press
,
New York
.
33.
Skogestad
,
S.
, and
Postlethwaite
,
I.
, 2005,
Multivariable Feedback Control: Analysis and Design
,
Wiley
,
New York
.
34.
Khalil
,
H. K.
, 2002,
Nonlinear Systems
, 3rd ed.,
Prentice-Hall
,
Upper Saddle River, NJ
.
35.
Antsaklis
,
P. J.
, and
Michel
,
A. J.
, 2006,
Linear Systems
,
Birkhäuser
,
New York
.
36.
Rayleigh
,
L.
, 1877,
The Theory of Sound
,
Dover
,
New York
, Vol.
1
.
37.
Caughey
,
T. K.
, and O’Kelly, M. E. J., 1965, “
Classical Normal Modes in Damped Linear Systems
,”
ASME Trans. J. Appl. Mech.
,
32
(3), pp.
583
588
.
38.
Meirovitch
,
L.
, 1997,
Principles and Techniques of Vibrations
,
Prentice-Hall
,
New York
.
39.
Ginsberg
,
J.
, 2001,
Mechanical and Structural Vibrations
,
Wiley
,
New York
.
40.
Meirovitch
,
L.
, 1967,
Analytical Methods in Vibrations
,
Macmillan
,
New York
.
41.
Feeny
,
B. F.
, 2002, “
On Proper Orthogonal Coordinates as Indicators of Modal Activity
,”
J. Sound Vib.
,
255
(
5
), pp.
805
817
.
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