###### Abstract  
This paper presents research on the mechanical characteristics of a synchronous axial magnetic coupling. The influence of the coupling structure on torque and axial force was analyzed. The considered parameters of the structure include the half-clutch diversity, the air-gap length between adjacent magnets, the magnetic characteristics of the backings' material, and the shape of the backings. It was discovered that the ferromagnetic backings that partially shroud magnets of the coupling cause a significant decrease of the maximum torque. The maximum torque and the maximum axial force decrease in nonlinear manner in response to the increasing magnets' height diversity, and the sensitivity of the parameters is larger in the upper range of the diversity. It was also disclosed that the air-gap length between the adjacent magnets has a minor influence on torque if the total volume of magnets is constant. A quantitative comparison of the maximum torque and maximum axial force for the couplings with both ferromagnetic backings, one ferromagnetic backing and with non-ferromagnetic backings is provided. The results were obtained using a 3D FEM numerical simulation. Physical experiments were performed for the numerical model verification. contactless mechanical power transmission; synchronous axial magnetic coupling; structure of coupling; mechanical characteristics; torque; axial force Article  
An Analysis of Axial Magnetic Coupling Force and Torque Dependencies on Its Structure Parameters Using a 3D FEM  
[PERSON], Vilkauskas, Vilkauskas, Vilkauskas, Vilkauskas, Vilkauskas, Vilkauskas, Vilkauskas, Vilkaus, V  
the traditional applications, magnetic couplings have been finding their place in novel appliances, as well as in control and robotic systems [12; 13]. Researchers have investigated the possibility to apply magnetic couplings instead of a lever-actuated friction clutch in wind plants for mechanical power transmission from turbine shaft to a motor shaft [14]. The advantage of a magnetic coupler to ensure motion transmission without a physical contact was also appreciated by novel product developers. Magnetic couplings were applied in a structure of an innovative design of a food and drink blender [15]. The structure of the blender, based on power transmission by magnetic couplings, assures convenience to its user as it releases a user from a mechanical fixing operation of the blender parts. In contrast to the active, electromagnet-based couplings, passive PM couplings themselves do not need any external power source and in an usual, synchronous mode they do not produce any noticeable heat during operation. In contrast to asynchronous eddy current magnetic couplings [16; 17], PM synchronous couplings provide more torque per volume, better efficiency and no heat dissipation during normal, synchronous mode operation. PM magnetic couplings are classified as an axial or radial type. In this work, we focused on axial (face-to-face)-type couplings [18]. Axial permanent magnet couplings (APMCs) are composed of two parallel discs (two half-clutches) separated by a small layer of air or/and other non-ferromagnetic medium gap. Each of the half-clutches consist of permanent magnets glued onto ferromagnetic or non-ferromagnetic backings. Permanent magnets of the discs are magnetized in directions parallel to the axis of the couplings. The magnetization directions are opposite in the adjacent magnets of each half-clutch. Since magnetic couplings have relevant properties for particular applications, a lot of attention has been paid to the analysis of the relationship between the mechanical characteristics and structural parameters of couplings. In [19], authors present a technique based on analytical expressions for torque and axial force calculations. They analyzed the distribution of magnetic flux density in APMCs, presented dependencies of the force and the torque vs. angular displacement, the air-gap length between half-clutches, and the number of pole pairs.