General responses of multi-degrees-of-freedom (MDOF) systems with parametric stiffness are studied. A Floquet-type solution, which is a product between an exponential part and a periodic part, is assumed, and applying harmonic balance, an eigenvalue problem is found. Solving the eigenvalue problem, frequency content of the solution and response to arbitrary initial conditions are determined. Using the eigenvalues and the eigenvectors, the system response is written in terms of “Floquet modes,” which are nonsynchronous, contrary to linear modes. Studying the eigenvalues (i.e., characteristic exponents), stability of the solution is investigated. The approach is applied to MDOF systems, including an example of a three-blade wind turbine, where the equations of motion have parametric stiffness terms due to gravity. The analytical solutions are also compared to numerical simulations for verification.

References

1.
Ruby
,
L.
,
1996
, “
Applications of the Mathieu Equation
,”
Am. J. Phys.
,
64
(
1
), pp.
39
44
.
2.
Li
,
Y.
,
Fan
,
S.
,
Guo
,
Z.
,
Li
,
J.
,
Cao
,
L.
, and
Zhuang
,
H.
,
2013
, “
Mathieu Equation With Application to Analysis of Dynamic Characteristics of Resonant Inertial Sensors
,”
Commun. Nonlinear Sci. Numer. Simul.
,
18
(
2
), pp.
401
410
.
3.
Ramakrishnan
,
V.
, and
Feeny
,
B. F.
,
2012
, “
Resonances of a Forced Mathieu Equation With Reference to Wind Turbine Blades
,”
ASME J. Vib. Acoust.
,
134
(
6
), p.
064501
.
4.
Inoue
,
T.
,
Ishida
,
Y.
, and
Kiyohara
,
T.
,
2012
, “
Nonlinear Vibration Analysis of the Wind Turbine Blade (Occurrence of the Superharmonic Resonance in the Out of Plane Vibration of the Elastic Blade)
,”
ASME J. Vib. Acoust.
,
134
(
3
), p.
031009
.
5.
Grimshaw
,
R.
,
2017
,
Nonlinear Ordinary Differential Equations
,
Routledge
, CRC Press, Boca Raton, FL.
6.
Hill
,
G. W.
,
1886
, “
On the Part of the Motion of the Lunar Perigee Which Is a Function of the Mean Motions of the Sun and Moon
,”
Acta Math.
,
8
, pp.
1
36
.
7.
Nayfeh
,
A. H.
, and
Mook
,
D. T.
,
2008
,
Nonlinear Oscillations
,
Wiley
,
New York
.
8.
Ishida
,
Y.
,
Inoue
,
T.
, and
Nakamura
,
K.
,
2009
, “
Vibration of a Wind Turbine Blade (Theoretical Analysis and Experiment Using a Single Rigid Blade Model)
,”
J. Environ. Eng.
,
4
(
2
), pp.
443
454
.
9.
McLachlan
,
N. W.
,
1961
,
Theory and Application of Mathieu Functions
,
Dover
,
New York
.
10.
Peterson
,
A.
, and
Bibby
,
M.
,
2013
,
Accurate Computation of Mathieu Functions
,
Morgan & Claypool Publishers
,
San Rafael, CA
.
11.
Hodge
,
D.
,
1972
, “
The Calculation of the Eigenvalues and Eigenfunctions of Mathieu's Equation
,” National Aeronautics and Space Administration, Columbus, OH, Report No.
NASA-CR-1937
.https://ntrs.nasa.gov/search.jsp?R=19720007908
12.
Rand
,
R. H.
,
1969
, “
On the Stability of Hill's Equation With Four Independent Parameters
,”
ASME J. Appl. Mech.
,
36
(
4
), pp.
885
886
.
13.
Rhoads
,
J. F.
,
Miller
,
N. J.
,
Shaw
,
S. W.
, and
Feeny
,
B. F.
,
2008
, “
Mechanical Domain Parametric Amplification
,”
ASME J. Vib. Acoust.
,
130
(
6
), p.
061006
.
14.
Taylor
,
J. H.
, and
Narendra
,
K. S.
,
1969
, “
Stability Regions for the Damped Mathieu Equation
,”
SIAM J. Appl. Math.
,
17
(
2
), pp.
343
352
.
15.
Insperger
,
T.
, and
Stépán
,
G.
,
2002
, “
Stability Chart for the Delayed Mathieu Equation
,”
Proc. R. Soc. London A
,
458
(
2024
), pp.
1989
1998
.
16.
Insperger
,
T.
, and
Stépán
,
G.
,
2003
, “
Stability of the Damped Mathieu Equation With Time Delay
,”
ASME J. Dyn. Syst. Meas. Control
,
125
(
2
), pp.
166
171
.
17.
Sharma
,
A.
, and
Sinha
,
S.
,
2018
, “
On Instability Pockets and Influence of Damping in Parametrically Excited Systems
,”
ASME J. Vib. Acoust.
,
140
(
5
), p.
051001
.
18.
Younesian
,
D.
,
Esmailzadeh
,
E.
, and
Sedaghati
,
R.
,
2005
, “
Existence of Periodic Solutions for the Generalized Form of Mathieu Equation
,”
Nonlinear Dyn.
,
39
(
4
), pp.
335
348
.
19.
Sofroniou
,
A.
, and
Bishop
,
S.
,
2014
, “
Dynamics of a Parametrically Excited System With Two Forcing Terms
,”
Mathematics
,
2
(
3
), pp.
172
195
.
20.
Ecker
,
H.
,
2011
, “
Beneficial Effects of Parametric Excitation in Rotor Systems
,”
IUTAM Symposium on Emerging Trends in Rotor Dynamics
,
Springer
, Dordrecht, The Netherlands, pp.
361
371
.
21.
Allen
,
M. S.
,
Sracic
,
M. W.
,
Chauhan
,
S.
, and
Hansen
,
M. H.
,
2011
, “
Output-Only Modal Analysis of Linear Time-Periodic Systems With Application to Wind Turbine Simulation Data
,”
Mech. Syst. Signal Process.
,
25
(
4
), pp.
1174
1191
.
22.
Sinha
,
S.
, and
Wu
,
D.-H.
,
1991
, “
An Efficient Computational Scheme for the Analysis of Periodic Systems
,”
J. Sound Vib.
,
151
(
1
), pp.
91
117
.
23.
Sinha
,
S.
, and
Butcher
,
E. A.
,
1997
, “
Symbolic Computation of Fundamental Solution Matrices for Linear Time-Periodic Dynamical Systems
,”
J. Sound Vib.
,
206
(
1
), pp.
61
85
.
24.
Kirkland
,
W. G.
, and
Sinha
,
S.
,
2016
, “
Symbolic Computation of Quantities Associated With Time-Periodic Dynamical Systems
,”
ASME J. Comput. Nonlinear Dyn.
,
11
(
4
), p.
041022
.
25.
Bolotin
,
V.
,
1965
, “
The Dynamic Stability of Elastic Systems
,”
Am. J. Phys.
,
33
(
9
), pp.
752
753
.
26.
Acar
,
G.
, and
Feeny
,
B. F.
,
2016
, “
Floquet-Based Analysis of General Responses of the Mathieu Equation
,”
ASME J. Vib. Acoust.
,
138
(
4
), p.
041017
.
27.
Acar
,
G.
, and
Feeny
,
B. F.
,
2016
, “
Approximate General Responses of Multi-Degree-of-Freedom Systems With Parametric Stiffness
,”
Special Topics in Structural Dynamics
, Vol. 6,
Springer
, Cham, Switzerland, pp.
211
219
.
28.
Acar
,
G. D.
, and
Feeny
,
B. F.
,
2018
, “
Bend-Bend-Twist Vibrations of a Wind Turbine Blade
,”
Wind Energy
,
21
(
1
), pp.
15
28
.
29.
Acar
,
G.
,
Acar
,
M. A.
, and
Feeny
,
B. F.
,
2016
, “
In-Plane Blade-Hub Dynamics in Horizontal-Axis Wind-Turbines
,”
ASME
Paper No. DETC2016-60344.
30.
Rand
,
R.
,
2012
, “
Lecture Notes on Nonlinear Vibrations
,” Cornell University, Ithaca, New York, accessed Dec. 5, 2017, http://www.math.cornell.edu/∼rand/randdocs/nlvibe52.pdf
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