Title page for ETD etd-72098-173139

Type of Document

Master's Thesis

Author

Fung, Jimmy Jr.

Author's Email Address

jfung@vt.edu

URN

etd-72098-173139

Title

Parameter Identification of Nonlinear Systems Using Perturbation Methods and Higher-Order Statistics

Degree

Master of Science

Department

Engineering Mechanics

Advisory Committee

Advisor Name	Title
M. R. Hajj (Co-chairman), A. H. Nayfeh (Co-chairman)	Committee Chair
D. T. Mook	Committee Member

Keywords

Nonlinear systems
system identification
parametric identification
higher-order statistics
bispectra
perturbation methods
method of multiple scales.

Date of Defense

1998-08-03

Availability

unrestricted

Abstract

A parametric identification procedure is proposed that combines
the method of multiple scales and higher-order statistics to
efficiently and accurately model nonlinear
systems. A theoretical background for the method of
multiple scales and higher-order
statistics is given.
Validation of the procedure is performed
through applying it to numerical simulations of two
nonlinear systems. The results show how the procedure can
successfully characterize the system damping and nonlinearities and
determine the corresponding parameters.
The procedure is then applied to experimental measurements from
two structural systems, a
cantilevered beam and a three-beam frame. The results show that
quadratic damping should be accounted for in both systems.
Moreover, for the three-beam frame, the parametric excitation is
much more important than the direct excitation.
To show the flexibility of the
procedure, numerical simulations of ship motion under parametric
excitation are used to determine nonlinear parameters govening the
relation between pitch, heave, and roll motions. The results show
a high level of agreement between the numerical simulation and the
mathematical model with the identified parameters.

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