A new magnetic core model for magnetorheological fluid-based applications considering fringing effect of gap and magnetic nonlinearity of fluids

This research aims to introduce a new magnetic core model for magnetorheological (MR) applications requiring high and wide controllable force. In general, the existing models linearize the magnetic behavior of magnetic cores for computational convenience. However, when MR applications such as MR damper require both high actuating force and relatively wide controllable force range, the nonlinearity of the magnetic properties becomes significant, which makes a big difference between the model and actual result. For this reason, the finite element method (FEM) is frequently adopted for modeling the magnetic cores, but it requires a lot of cost and time. To compensate for these disadvantages, a new nonlinear magnetic core model considering both the nonlinearity of the B-H curve of MR fluid and the fringing effect of the gap is proposed in this work. The approach is an extension of Kirchhoff's law, which performs conformal mapping and backward calculation techniques. After formulating the analytical model, a magnetic core with specific parameters is designed as an illustrative example to validate the proposed model. It is shown through comparative investigations on the proposed model, linearization model, and FEM model that the proposed model is very effective to predict the high controllable force of MR applications.