Design and analysis of a non-hysteretic passive magnetic linear bearing for cryogenic environments

Abstract

In this study, the mechanical design and analysis of a magnetic levitating linear bearing suitable for working in the nonhysteretic range of forces is presented. The semi-cylindrical design of the superconductor provides stable equilibrium positioning and restoring forces in all degrees of freedom except for two with a cylindrical magnet floating along the axis of revolution/displacement. Using finite element analysis, it has been proven that the magnet can float stably and passively in a complete non-hysteretic Meissner state. This non-hysteretic passive linear bearing could be suitable for long-stroke precision positioning. The high translational symmetry of the magnetic field seen by the superconductor assures a usable long stroke of around AE90 mm with full performance and AE150 mm with reduced performance. This linear bearing in combination with an actuating system for only one degree of freedom could be used for accurate precision positioning systems for cryogenic environments with zero hysteresis in the movement.

Analysis of the Static and Dynamic Behavior of a Non Hysteretic Superconductive Passive Magnetic Linear Bearing by Using an Electromagnetic Integral Formulation

“…The total number of elementary volumes used to model the whole system is N = 10 × 10 3 ; the magnet and the SC are discretized respectively with n = 75 and m = 9925 elements. Although the code is able to deal with all the 6 DOF, in Section 4 some constraints reducing the number of DOF have been introduced in order to allow the comparison with the results described in [18]. In Section 5 the system has been simulated considering only 3 DOF (preventing rotations of the PM) in order to verify the consistency of the results.…”

“…Refer to the cited paper ( [18]) for a detailed description of this SML-based linear bearing and its operation. For the sake of subsequent clarity, here below the main characteristics are described.…”

“…In a previous paper [18], the authors presented the mechanical design of a magnetic levitating linear bearing, suitable for working in the non-hysteretic range of forces, also assuring a usable long stroke of around ±90 mm with full performance and ±150 mm with reduced performance. In the same paper, the analysis of forces and pressures for each direction was performed by using a finite element model.…”

“…With respect to the analysis described in [18], the innovation point consists in the use of a different formulation capable to simulate also the dynamic behavior of the superconductive device. In fact, in [18] only static FEM simulations of the device with a reduced number of DOF were described. Unfortunately, in that paper the analysis of the device cannot be satisfactorily extended to simulate the full 6 DOF dynamic behavior, due to the above cited limitations of the FE model.…”

The autonomous car—a blessing or a curse for the future of low carbon mobility? An exploration of likely vs. desirable outcomes

“…Travel speed can be up to three times higher compared to conventional rail services, whereas infrastructure costs would be three times less than conventional underground rail services. It is based on the application of superconducting levitation by the use of contactless mechanical components which convert torque into movement through magnets [24,25], and it increases efficiency while reducing fuel consumption and emissions. Ultimately, its gains are achieved by allowing vehicles to travel together while still having the autonomy to reach specific destinations individually [23].…”