Structural mechanics analytical module (SM1)


This analytical structural mechanics module includes the calculation of the outer structure (stator or rotor) natural frequencies by modelling it as an equivalent cylinder where the winding or magnet mass is also taken into account. The mass effect of the winding can be tuned through the winding coupling factor Input.Mechanics.wcf, which depends on the winding technology and impregnation type.

The model used in MANATEE is closed from (J. F. Gieras, C. Wang, Joseph Cho Lai, “Noise of polyphase electric motors”, CRC Press, 2005), including both extensional modes (purely circumferential) and modes involving longitudinal deflections. However some empirical stiffening coefficients obtained by EOMYS experience on more than 50 electrical machines are used to account for pressure plates.

The calculation of radial dynamic deflections of the structure under radial electromagnetic forces is also based on an equivalent 2D ring model.

The limits of this model depend on the geometry of the stator, especially the number of teeth and the relative tooth to yoke height. For small number of teeth and long teeth it is recommended to use MANATEE coupling with structural FEA software.

Application to e-NVH

This fast model can be used when ranking electrical machines NVH behaviour during early electromagnetic design loops (e.g. sweep of different slot/pole combination). The vibration calculation should be refined in structural FEA software once the detailed CAD model of the housing is known.


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