Application of conditioned reverse path method to large multi-degree-of-freedom nonlinear structure

Abstract

Nonlinear system identification (NSI) has received a fair amount of attention in recent years. The highlyindividual nature of nonlinearity makes it important to fully understand the implication of nonlinear behavior.Nevertheless, the application of NSI to a more complex multi-degree-of-freedom (MDOF)system is still scarce andlimited. A spectral approach called the Conditioned Reverse Path (CRP) method is chosen to test the capability of saidmethod in identifying underlying linear characteristics. A 240 degree-of-freedom airplane-like structure with a cubicnonlinearity attached between the wings and the engines is modelled using MSC Patran/Nastran software to generate thedesired responses. The obtained responses are then imported to Matlab software to proceed with spectral analysis utilizingthe CRP method. Unfortunately, the CRP could not depict its capability as one of the advantageous method in the NSI areaand further works are necessary to improve the airplane-like modelling thus determine the true underlying linear system.Once the modelling is reliable to be applied in the CRP, a more recent method called the Orthogonalised Reverse Path(ORP) method will be applied as future works.