Vibration testing of large scale nonlinear structures

Vibration testing is used as a means of validating Finite Element models and also to measure modal damping. The classical approach typically assumes that the system is linear. With the need to improve system performance, aerospace and automotive structures are being designed with much lighter construction and also much less inherent damping, consequently structural nonlinearities have a much greater effect on performance. Although there has been significant effort towards the development of nonlinear modal analysis methodologies, these techniques are still not at a stage where they can be used on industrial size structures. This paper describes an experimental investigation on a structure with the characteristics of large scale weakly nonlinear industrial structure. It presents a procedure able to extract backbone curves from decay responses. This enables measurements to be made in regimes where nonlinear effects are more significant. Conclusions are drawn as to the most effective approaches for future developments and industrial application.