Investigating Nonlinearities in a Demo Aircraft Structure under Sine Excitation

Developing on the basic idea behind parametric and non-parametric identification of nonlinear systems, another case study on integrating system identification and finite element modelling of nonlinear structures is presented. The first step, which is the focus of this paper, involves using acquired input and output data to derive an experimental model for both the underlying linear model and nonlinear model of the proposed structure, no information about the system is required and only the applied excitations and corresponding accelerations are implemented in the nonlinear identification step. The proposed case study is demonstrated on a nonlinear simple metallic plane assembly with localized stiffness and damping nonlinearities; in this case, an updated linear finite element model of the structure is derived and the nonlinearities experimentally characterised.