noise & vibrations
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Noise & Vibrations. xxx. www.tianyuantech.com www.magsoft-flux.com www.cedrat.com. Content. Inroduction Coupling LMS – Direct Method Rinciple Implementation Couping NASTRAN – Indirect Method. Introduction . - PowerPoint PPT PresentationTRANSCRIPT
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Noise & Vibrationsxxx
www.tianyuantech.comwww.magsoft-flux.comwww.cedrat.com
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ContentInroductionCoupling LMS – Direct MethodRincipleImplementationCouping NASTRAN – Indirect Method
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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
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How it worksExport magnetic forces computed by FLUX to mechanical CAE tools for vibro-acoustic studies.
Flux applications:2D Transient Magnetics3D Transient MagneticsSKEW Transient Magnetics
mechanical CAE tools:MSC NASTRAN/ACTRANLMS Virtual.Lab
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How it works
Calculation and visualization of magnetic forces
Import :File1.bulk
File.unv
PATRAN
NASTRAN
Virtual.Lab
Export: File2.bulk
Indirect Method
Direct Method
Support for computation
Forces on support
Forces and support
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How it works in FLUXNew function in a new dedicated contextMenu [Computation]/[Open mechanical analysis context]
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Coupling to MSC NastranMagnetic pressures: Maxwell tensor Only for the rotating machines.Computed in the air gap.On a circle (2D) or a cylinder (3D et Skew)
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Coupling to MSC NastranVibro-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:
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0 211
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tn HB
tn HB
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Coupling to MSC Nastran
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Coupling to Virtual.Lab
Geometry
Mesh
Physics Solving Post-processing
Import of Forces from Flux
Structural Model + Modal Basis
Mapping to Structural Model + Vibration
ResponseAcoustic Respons
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Coupling to Virtual.Lab
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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
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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
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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
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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
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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)
Coupling to Virtual.Lab
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Thank you for your interest in our modelling solutions
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