Identification of a Nonlinear Wing Structure Using an Extended Modal Model

The nonlinear resonant decay method identifies a nonlinear dynamic system using a model based in linear modal space comprising the underlying linear system and a small number of additional terms that represent the nonlinear behavior. In this work, the method is applied to an aircraftlike wing/store/pylon experimental structure that consists of a rectangular wing with two stores suspended beneath it by means of nonlinear pylons with a nominally hardening characteristic in the store rotation degree of freedom. The nonlinear resonant decay method is applied to the system using multishaker excitation. The resulting identified mathematical model features five modes, two of which are strongly nonlinear, one is mildly nonlinear, and two are completely linear. The restoring force surfaces obtained from the mathematical model are in close agreement with those measured from the system. This experimental application of the nonlinear resonant decay method indicates that the method could be suitable for the identification of nonlinear models of aircraft in ground vibration testing.

[1]  Keith Worden,et al.  Genetic algorithm with an improved fitness function for (N)ARX modelling , 2007 .

[2]  Dennis Göge,et al.  Detection and description of non-linear phenomena in experimental modal analysis via linearity plots , 2005 .

[3]  P. Guillaume,et al.  The PolyMAX Frequency-Domain Method: A New Standard for Modal Parameter Estimation? , 2004 .

[4]  John Crowley,et al.  THE MULTIVARIATE MODE INDICATOR FUNCTION IN MODAL ANALYSIS , 1985 .

[5]  Dennis Göge,et al.  INTL - A Strategy for the Identification and Characterization of Non-linearities within Modal Survey Testing , 2004 .

[6]  Jonathan E. Cooper,et al.  Identification of multi-degree of freedom non-linear systems using an extended modal space model , 2009 .

[7]  P. Beran,et al.  Studies of Store-Induced Limit-Cycle Oscillations Using a Model with Full System Nonlinearities , 2004 .

[8]  S. Masri,et al.  Nonparametric Identification of Nearly Arbitrary Nonlinear Systems , 1982 .

[9]  S. N. Balakrishnan,et al.  Parameter Estimation in Nonlinear Systems Using Hopfield Neural Networks , 2005 .

[10]  Keith Worden,et al.  An extension of force appropriation to the identification of non-linear multi-degree of freedom systems , 2000 .

[11]  Jonathan E. Cooper,et al.  Identification of Non-Linear Dynamic Systems using an Expert Approach , 2006 .

[12]  Jonathan E. Cooper,et al.  Identification of Structural Free-play Non-linearities using the Non-Linear Resonant Decay Method , 2006 .

[13]  Dennis Goege.  Fast Identification and Characterization of Nonlinearities in Experimental Modal Analysis of Large Aircraft , 2007 .

[14]  Michael Sinapius,et al.  Influence and characterisation of weak non-linearities in swept-sine modal testing , 2003 .

[15]  Rick Lind,et al.  WAVELET ANALYSIS TO CHARACTERISE NON-LINEARITIES AND PREDICT LIMIT CYCLES OF AN AEROELASTIC SYSTEM , 2001 .

[16]  Dennis Göge,et al.  Advanced Test Strategy for Identification and Characterization of Nonlinearities of Aerospace Structures , 2005 .

[17]  Sheng Chen,et al.  Identification of MIMO non-linear systems using a forward-regression orthogonal estimator , 1989 .

[18]  M. Sinapius,et al.  Tasks for improvement in ground vibration testing of large aircraft , 2001 .