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Content Inroduction Coupling LMS – Direct Method Rinciple Implementation Couping NASTRAN – Indirect Method

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

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

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

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

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)

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

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)

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:

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.

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

Coupling to MSC Nastran

Coupling to MSC Nastran

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

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.

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

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

Coupling to Virtual.Lab

Coupling to Virtual.Lab

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)

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

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

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

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

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

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)

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