Modeling and Simulation of a Tubular Linear Switched Reluctance Actuator

In this paper, 2-D finite element analysis and MATLAB/Simulink software are used to model and simulate the proposed tubular linear switched reluctance actuator. The analysis of the actuator by finite element is essential for determining the magnetization characteristics. The obtained data from the analysis is useful for testing and verifying the machine operation performance and behavior. According to the analysis, when a step current signal of 3A was applied to the actuator, oscillation occurred at beginning of the motion with maximum overshooting of 2mm and settling time of 0.15s. Besides, the force analysis showed there was nonlinear force behavior between - 3.5N and 2N observed from the actuator motion. The saturation and nonlinear magnetization curve of materials causes the nonlinearity characteristics of thrust force and magnetic flux which affect the performance of the actuator. The determination of the characteristics and performance is crucial for the proposed actuator to realize a precision positioning system in the future.

Small-amplitude static periodic patterns at a fluid–ferrofluid interface

We establish the existence of static doubly periodic patterns (in particular rolls, squares and hexagons) on the free surface of a ferrofluid near onset of the Rosensweig instability, assuming a general (nonlinear) magnetization law. A novel formulation of the ferrohydrostatic equations in terms of Dirichlet–Neumann operators for nonlinear elliptic boundary-value problems is presented. We demonstrate the analyticity of these operators in suitable function spaces and solve the ferrohydrostatic problem using an analytic version of Crandall–Rabinowitz local bifurcation theory. Criteria are derived for the bifurcations to be sub-, super- or transcritical with respect to a dimensionless physical parameter.