Wall, FranziskaFranziskaWallSchenk, Hermann A.G.Hermann A.G.SchenkMelnikov, AntonAntonMelnikovKaiser, BertBertKaiserSchenk, HaraldHaraldSchenk2024-03-072024-03-072023https://publica.fraunhofer.de/handle/publica/46393310.1007/s11071-023-08811-12-s2.0-85168143441For electrostatic actuators, the pull-in marks an upper limit for the operation range. Once reached, the electrodes come into contact and are shorted without further protection. A non-destructive measurement technique to predict this failure mode is of high interest to allow, e.g. fabrication monitoring or reliability studies. To this end, we develop a surprisingly simple nonlinear lumped parameter model (LPM) for a rather complex electrostatic actuator, designed for an in-ear loudspeaker application. It turns out that a single degree-of-freedom model with only one parameter is sufficient. Our key approach is to experimentally determine this free model parameter by analysing harmonic distortions at low frequencies. Harmonic distortions are a very sensitive tool for nonlinearities. Our method is suggested by simulations with a 2D stationary finite element method (FEM), demonstrating how the analysis of harmonic distortions for voltages far below the pull-in can predict not only the DC pull-in but also the quasi-static AC pull-in voltages at different working points. The distortion analysis of electrostatic actuator ensembles therefore seems a viable route for their non-destructive characterization in the nonlinear domain.enElectrostatic actuatorHarmonic distortionsMicro-speakerPull-injournal article