On the describing functions for dampers with freeplay and dry friction for studying nonlinear oscillations

This work presents a novelty in the mathematical formulation of a damper with freeplay for structural dynamics analysis in the frequency domain. This theoretical model represents the basis for the application of the harmonic balance technique for simulating problems with nonlinear characteristics. The predictions of the mathematical model proposed in this work are confronted with results obtained on a ground test of an apparatus composed of a damper and an attachment with a fixed amount of freeplay. The results indicate that the proposed mathematical model can capture the nonlinear characteristics of a damper with freeplay and, therefore, be used for nonlinear structural dynamics analyses, mainly focused on aeroelastic stability.