Nonlinear vibration analysis of a complex aerospace structure
Samson Cooper
10.17862/cranfield.rd.4288874.v2
https://cord.cranfield.ac.uk/articles/dataset/Nonlinear_vibration_analysis_of_a_complex_aerospace_structure/4288874
<p>Technical paper presented at the 2016 Defence and Security Doctoral Symposium.<br></p><p>Complex
shaped aerodynamic structures such as deployable missiles are prone to exhibit
some level of nonlinear phenomena due to their aerodynamic tailored design and
application. Aside from the aeroelastic control challenges experienced by a
missile, a fundamental challenge encountered by a deployable missile is the
inevitable concentrated structural nonlinearities which are observed around the
hinge of its fins. Due to the current design and manufacturing process, the
hinge of the fin of a missile often consist of complex configurations, such as
joints, friction and other nonlinear features which may lead to concentrated
structural nonlinearities. Some of the nonlinearities encountered includes
piecewise linearity, bilinear nonlinearity, hysteresis, coulomb friction and
nonlinear damping mechanisms. These nonlinearities are frequently triggered at
large vibration amplitudes, caused by high pressure loads during operational
flight. Activation of these nonlinearities often affect the dynamic response of
the missile and in some cases lead to structural failures in the major
components of the air vehicle. In this context, identifying and predicting the
vibration response of such aerodynamic structures with nonlinearities, may be
of great advantage to the present structural dynamic community. </p>
<p>In this paper, the nonlinear
dynamic behaviour of a B61 prototype missile has been examined. A two-step
methodology for integrating nonlinear system identification for estimating
nonlinear stiffness and damping mechanism and nonlinear finite element
modelling has been adopted in this investigation. The first step made use of
acquired input and output data from random and sine sweep vibration test to
derive a nonlinear experimental model for the missile, where the nonlinear
experimental model was developed using a white box identification process,
namely (detection, characterisation and parameter estimation). The second step
implements the parameters of the identified nonlinear system into a finite
element model (FEM) of the missile to develop a nonlinear FEM. The nonlinear
dynamic response of the FEM was computed using the Harmonic balance method (HB)
and pseudo-arclength continuation in the frequency domain. In addition, Force
controlled stepped sine experiments at several excitation levels were conducted
to validate the numerical solution obtained from the nonlinear FEM computation.
The results obtained were used to understand the amplitude dependant behaviour
of the missile under a vibration controlled environment and in addition predict
the dynamic response of the missile in the existence of deployable hinge
nonlinearity.</p>
2016-12-08 11:03:23
Nonlinear identification
Structural nonlinearities
Vibrations
DSDS16 technical paper
DSDS16
Aerodynamics (excl. Hypersonic Aerodynamics)