Equivalent circuit model of eddy current damping regarding frequency-dependence with test validation

Abstract

This study proposes an equivalent circuit model to simulate the mechanical behavior and frequency-dependent characteristic of eddy current (EC) damping, with the validations from multi-physics finite element (FE) modeling and dynamic testing. The equivalent circuit model is first presented with a theoretical expression of the EC damping force. Then, the transient analysis with an ANSYS-based FE model of an EC damper is performed. The time-history forces from the FE model are compared with that from the proposed equivalent circuit model. The favorable agreement indicates that the proposed model can simulate the nonlinear behavior of EC damping under different excitation scenarios. A noncontact and friction-free planar EC damper is designed, and its dynamic behavior is measured by employing shake table testing. The experimental observations can be reproduced by the proposed equivalent circuit model with reasonable accuracy and reliability. The proposed equivalent circuit model is compared with the classical viscous model and the higher-order fractional model using a complex EC damper simulated in ANSYS to show the advantages of the proposed model regarding model simplicity and prediction accuracy. A single-degree-of-freedom (SDOF) structure with different EC damping models is further analyzed to illustrate the need for accurate EC damping modeling.