Using Little-Shear-Modulus Model To Solve The Eigenfrequency Of AMB Rotor With Lamination Stack

In AMB design, the lamination stack is a general part of the rotor. It consists of pieces of stalloy, which is designed as very thin steel plate coating with special isolative paint. These sheets of assembly stacking stalloy will definitely influence the eigenfrequency and other dynamic effects of the rotor. But, considering the lamination’s mechanical character, this influence is difficult to be well counted in the AMB design. Some simplified ways are used in solving this kind of problem, such as modeling the lamination as a part of the rotor and neglecting its rigidity influence. In this paper, two of these useful simple model solutions are studied and compared. Finally, the Little Shear Modulus (LSM) Model, a new model will be introduced, which exactly simulates the mechanical characters of the lamination stack and is easy to understand as well. An assumed simple rotor example is used to demonstrate this model. The eigenfrequency of this assumed rotor is solved by several models at the same time, and the comparison proves that the LSM model can give more reasonable result. Finally, an example is shown on how this LSM model is used to solve the eigenfrequency of an actual grinder rotor.