1. Noise & Vibrations www.tianyuantech.com www.magsoft-flux.com
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2. Content
Inroduction Coupling LMS – Direct Method Rinciple Implementation Couping NASTRAN – Indirect Method

3. Introduction
Today, motors are used in many applications close to the user. The noise pollutes the environment of the user. It is a nuisance that must be mitigated.
Origin of the noise in motors:
Driving electronic
Torque ripple on gears
Electromagnetic forces on stator
Coils
To reduce the noise level, a clear identification of the noise and its source is needed.
FLUX is connected to vibrational tool

4. How it works
Export magnetic forces computed by FLUX to mechanical CAE tools for vibro-acoustic studies.
Flux applications:
2D Transient Magnetics
3D Transient Magnetics
SKEW Transient Magnetics
mechanical CAE tools:
MSC NASTRAN/ACTRAN
LMS Virtual.Lab

5. How it works Indirect Method Direct Method PATRAN NASTRAN Virtual.Lab
Support for computation
PATRAN
Import :File1.bulk
Indirect Method
NASTRAN
Export: File2.bulk
Forces on support
Calculation and visualization of magnetic forces
Direct Method
Virtual.Lab
File.unv
Forces and support

6. How it works in FLUX
New function in a new dedicated context Menu [Computation]/[Open mechanical analysis context]

7. How it works in FLUX
The main functions available in this new context are:
Creation of new computation support.
Computation of the magnetic forces.
Results visualization
Results export in multiphysics files to:
MSC NASTRAN (.bulk)
LMS Virtual.Lab (.unv)

8. Coupling to MSC Nastran
Geometry
Mesh
Physics
Solving
Post-processing
Analysis on one mechanical period + Forces computation + Visualization + Forces export
Transient application
Forces import from Flux
Vibratory response
Geometry
Mechanical mesh
Acoustic response

9. Coupling to MSC Nastran
Magnetic pressures: Maxwell tensor Only for the rotating machines. Computed in the air gap. On a circle (2D) or a cylinder (3D et Skew)

10. Coupling to MSC Nastran
Vibro-acoustic analysis must be performed on a full mechanical cycle (360°mech).
The time sampling and the mesh must be set to take into account:
space harmonics.
time harmonics
Computation in FLUX can be performed using periodicities. The signal is automatically rebuilt to the full mechanical cycle.
Magnetic pressures will be calculated in the airgap, tangential and normal comp.
Normal component:
Tangential component:

11. Coupling to MSC Nastran
Step
Software
Description 1
MSC NASTRAN
Preparation of the MSC NASTRAN project:
Standard description: geometry, physics (The same characteristics with the Flux project) and the mechanical mesh.
Export the mechanical mesh as a (.bulk) file which be used in Flux. 2
Flux
Preparation of the Flux project :
Geometry, mesh, physics (Transient application) and solving. 3
During post-processing:
Open mechanical analysis context.
Import mechanical support built in NASTRAN
Create computation support in the air gap.
Calculate the magnetic forces on the computation support and project this forces on the nodes of the mechanical support.
Visualize the magnetic forces. 4
Export magnetic forces to MSC NASTRAN as a (.bulk) file 5
Import the (.bulk) file containing the calculated magnetic forces in Flux and make the vibro-acoustic analysis.

12. Coupling to MSC Nastran
Computation support created in MSC, imported in FLUX Cylinder in airgap – coupling only for radial motors (cylindrical airgap) Imported in FLUX (2D, SKEW, 3D)
Mechanical Support
Computation Support
Sliding Cylinder
Rotor radius

13. Coupling to MSC Nastran

14. Coupling to MSC Nastran

15. Coupling to Virtual.Lab
Geometry
Mesh
Physics
Solving
Post-processing
Import of Forces from Flux
Structural Model + Modal Basis
Mapping to Structural Model + Vibration Response
Acoustic Respons

16. Coupling to Virtual.Lab
Magnetic pressures computation:
In FLUX: dFmag/dS (already implemented)
Computation performed on borders between magnetic regions and air or vacuum regions
The magnetic pressures are transformed to magnetic forces on each nodes of FLUX mesh.
General method not limited to radial machines.

17. Coupling to Virtual.Lab
Create the computation support on which the magnetic forces will be calculated.

18. Coupling to Virtual.Lab
The computation support is created for the whole geometry even is the periodicity is taken into account. The support will be exported as a 3D support with the corresponding magnetic forces on each nodes.
Computation support on the stator teeth

19. Coupling to Virtual.Lab

20. Coupling to Virtual.Lab

21. Coupling to Virtual.Lab
Only the time signal is exported on each nodes of the Flux mesh
If Flux 2D is used  We must indicate the layer number on the depth of the machine before exporting
17N
17N 1N 1N 1N
Magnetic forces calculated with Flux 2D
(Total Forces on the depth )
17 layers on 170 mm
Forces exported as (.unv) file
(Indicate the layers number on the depth)

22. Coupling to Virtual.Lab
Step
Software
Description 1
Flux
Preparation of the Flux project :
Standard description  : geometry, mesh, physics (Transient application) and solving 2
In the post-processing:
Go to mechanical analysis context
Create a computation support
Compute magnetic forces on the support.
Visualize the magnetic forces 3
Export the magnetic forces to LMS Virtual.Lab in (.unv) file 4
LMS Virtual.Lab
Preparation of the LMS Virtual.Lab project:
Geometry 3D: The same geometric dimensions and the same physic characteristics as the Flux project. 5
Import the (.unv) file containing the computed magnetic forces from Flux. 6
Structural model + Modal basis
Mapping of the structural model + Vibratory response
Acoustic response

23. Coupling to Virtual.Lab – A Salient Pole Motor
Mechanical Power
Mean Value
55 kW
Rotor velocity
7500 rpm
Currents in phases
Peak value (sinus wave)
70 A
Field current
Constant value
10 A

24. Coupling to Virtual.Lab
The UNV file containing the EM Surface Mesh and time domain forces is imported in LMS Virtual.Lab Acoustics The user can inspect the force distribution per time step and animate the forces in time domain

25. Coupling to Virtual.Lab
Structural model + Modal basis
Contains stator, windings, end caps, housing One homogenized but orthotropic material is chosen to model the stator (stiffness) In first instance, a modal basis is used to capture the dynamics of the structure

26. Coupling to Virtual.Lab
Forces mapping to structural model + Modal basis
LMS Virtual.Lab maps the EM Forces conservatively from the EM surface to the coarser structural mesh surface A Fourier transform provides frequency domain forces These forces are used to compute the vibration response

27. Coupling to Virtual.Lab
Acoustic response
LMS Virtual.Lab Acoustics further computes the acoustic radiation:
SPL
Sound Power
Directivity
Enabling technologies ensuring a fast acoustic simulation result: FEM Acoustics, AML (PML technology)
The results show clearly the harmonic content (7500 RPM  stator teeth freq = 6 kHz, rotor pole freq = 500 Hz) of the forces as well as the modal content of the structure (eg first breathing mode around 3 kHz)

28. Thank you for your interest in our modelling solutions
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