Modal basis import


Noise and vibration induced by e-motor operation can be calculated with Manatee software though modal basis import of a third-party 3D FEA mechanical model. Contrary to analytic NVH models, a 3D FEA mechanical model allows to accurately model the effect of electric machine mechanical integration (e.g. rotor housing coupling mode, rotor bending modes, housing boundary conditions). It is especially useful when introducing tolerances and faults during e-NVH calculations.


Contray to basic design phase during which electrical engineers do not know the mechanical environment of the electrical machine, a first version of the mechanical integration is known in detailed design phase as a CAD model of rotor, stator, housing and driveline assembly. At this development stage, the type of lamination interference fit, e-motor cooling and driveline architectures are known. A 3D FEA mechanical model can therefore be defined by a mechanical engineer and electrical machine mechanical properties can be tuned by fitting the model with an Experimental Modal Analysis.

Once the 3D FEA mechanical model is built, it can be represented by its modal basis. Modal basis format may depend on the third party mechanical software that is used. The modal basis assumes a linear behaviour of the mechanical assembly. If necessary, the mechanical assembly is linearized around a particular operating point (e.g. under a certain load, assuming a certain eccentricity level).

The import of a 3D FEA modal basis in Manatee can be carried with up to 6 billions degrees of freedoms based on EOMYS consulting experience. It can contain complex coupling elements for the modelling of bearings and gears.


For more information on how to prepare a 3D FEA mechanical model and modal analysis for use in Manatee e-NVH software from Altair Optistruct, 3DS Abaqus or Ansys Mechanical, you can have a look at these guidelines: Modal_import_procedure.pdf

 Before running modal analysis in the third party 3D FEA mechanical model, it is important to identify the nodes where vibration must be calculated by Manatee, as well as the nodes of the surfaces radiating acoustic noise. Several surfaces can be defined to run panel contribution analysis under Manatee.