Nonlinear System Identification of an F-16 Aircraft Using the Acceleration Surface Method

In most mechanical engineering applications, the purpose of nonlinear system identification is to upgrade and update a linear finite element (FE) model. Nonlinear elements, whose parameters are found during the identification procedure, are locally added to this linear model to better reproduce the experimental results.
The following nonlinear system identification method takes place in this framework, where a linear FE model of the structure is assumed to be available. A nonlinearity characterization
step is first performed using qualitative nonlinear stiffness curves computed with the Acceleration Surface Method (ASM). This step enables to determine the location and the mathematical form of the nonlinear elements to add in the FE model. The parameters of those nonlinear elements are then identified by optimization, using the error between the ASM curves from the experiments and the numerical model as a cost function.
The case of an F-16 aircraft exhibiting nonlinearities at the wing-to-payload mounting interfaces [1] is considered and a FE model of the right wing and its connected payload is used as a starting point.