Systems with bilinear stiffness: Extraction of backbone curves and identification

With the need to improve system performance, aerospace and automotive structures are being designed with much lighter construction and also much less inherent damping. A consequence of this is that structural nonlinearities have a much greater effect on the static and dynamic performance.Although there has been significant effort recently towards the extension of modal analysis to identify structural nonlinearities, these techniques are still not at a stage where they can be used on industrial size structures. This paper describe an experimental investigations on a structure model containing two bilinear stiffness elements. A method for the estimation of the characteristic backbone curves of the nonlinear system is first discussed and then used to characterise the active nonlinear elements from experimental data. Conclusions are drawn as to the most effective way to extend the proposed method for future industrial applications.