**Papers Published**

- Knight, J.D. and Xia, Z. and McCaul, E. and Hacker, H. Jr.,
*Determination of forces in a magnetic bearing actuator: Numerical computation with comparison to experiment computation with comparison to experiment*, Journal of Tribology, Transactions of the ASME, vol. 114 no. 4 (1992), pp. 796 - 801 .

(last updated on 2007/04/06)**Abstract:**

Calculations of the forces exerted on a journal by a magnetic bearing actuator are presented, along with comparisons to experimentally measured forces. The calculations are based on two-dimensional solutions for the flux distribution in the metal parts and free space, using finite but constant permeability in the metals. Above a relative permeability of 10^{4}the effects of changes in permeability are negligible, but below 10^{4}decreases in permeability cause significant decreases in the force. The calculated forces are shown to depend on the metal permeability more strongly when the journal is displaced from its centered position. The predicted forces in the principal attractive direction are in good agreement with experiment when a relatively low value of permeability is chosen. The forces measured normal to the axis of symmetry when the journal is displaced from that axis, however, are significantly higher than predicted by theory, even with a value of relative permeability larger than 5000. These results indicate a need for further work including nonlinear permeability distributions.**Keywords:**

Magnetic bearings;Antifriction bearings;Force measurement;Mechanical permeability;Vibration control;Approximation theory;