Prediction of the non-linear response of a clamped panel to acoustic loading

Aircraft skin panels may often be subjected to high levels of acoustic pressure loading in flight that may lead to acoustic fatigue. In some cases, the in-plane restraint provided by the panel boundaries will introduce a stiffening non-linearity when the panel deforms. The Non-Linear Modal method (NLMOD) allows the efficient prediction of the kinematic and stress response of such panels via a reduced order approach that converts FE results into a model based in linear modal space, with additional terms included to represent the non-linear behaviour. In this paper, the development of a simple experimental clamped panel is presented, together with a Finite Element model of the same structure. The panel is exposed to fairly high-level acoustic excitation in a Progressive Wave Tube (PWT) and the resulting responses are compared to those predicted using the identified non-linear modal model.