acoustical optimization of a train gearbox based …group powertrain and gearbox acoustics...

© Fraunhofer IWU Manuel Haase, 23.05.2017 1st Romax Japan User Forum 2017, 23rd May, Yokohama (JPN)

ACOUSTICAL IMPROVEMENT OF A TRAIN GEARBOX BASED ON GEAR MICROGEOMETRY AND HOUSING GEOMETRY OPTIMIZATION

Manuel Haase, Jan Bräunig, Eric Hensel Fraunhofer Institute for Machine Tools and Forming Technology IWU, Dresden, Germany

© Fraunhofer IWU Manuel Haase, 23.05.2017

2 1st Romax Japan User Forum 2017, 23rd May, Yokohama (JPN)

AGENDA

Who we are

Introduction

Simulation procedure

Acoustical optimization

Simulation and optimization results

Conclusion



AGENDA

Who we are

Introduction




Conclusion



Who we are - The Fraunhofer IWU Founded July 1st, 1991

About 610 employees

Budget: 40 Mio €

Central topic: Resource efficient production

3 locations:

Chemnitz (head quarter)

Machine tools

Forming technology

Cutting technologies

Dresden (since 2001)

Adaptronics

Technical Acoustics

Joining technology

Medical engineering

Head quarter in Chemnitz

Zittau (since 2011)

plastics technology

München Freiburg

Freising Stuttgart

Pfinztal Karlsruhe Saarbrücken

St. Ingbert Kaiserslautern

Darmstadt Würzburg

Erlangen

Ilmenau

Teltow

Oberhausen

Duisburg

Euskirchen Aachen St. Augustin Schmallenberg

Dortmund

Potsdam Berlin

Lübeck Itzehoe

Braunschweig

Hannover

Bremen Bremerhaven

Jena

Leipzig

Chemnitz

Dresden

Magdeburg

Halle

Wachtberg

Ettlingen

Kassel

Augsburg

Bronnbach



Acoustical s imulation methods

Finite Element Modelling

Multi Body Simulation

Network models

Analytical approaches

Development of active and pass ive systems for noise and vibration reduction

Mechanical engineering

Vehicle industry

Railway industry

Wind power industry

Psychoacoustics

Analysis of sound using sound pressure level and frequency analysis in combination with psycho-acoustical parameters to investigate the subjective listening perception

Acoustical analys is methods

Air-borne noise (sound power, sound source localization using microphone array)

Structure-borne noise (laser scanning vibrometer, shaker test bench)

Who we are - Department Technical Acoustics



Acoustics of Electrical Drives

Gear/ Gearbox Acoustics

S imulation Methods

FEM, MBS, analytical

Ansys, Romax, Matlab, Simulink

Who we are - Department Technical Acoustics Acoustical development of electrical drive trains

Measurement Methods

Test rigs for measurement of dynamic properties

Gear contact anaylsis in ROMAX

Analysis of electromagnetic forces in Ansys Maxwell

Gearbox test rig Electrical drive test rigs



AGENDA

Who we are

Introduction




Conclusion



Introduction Sound sources on railway vehicles

Source: Thoß, E.; Stegmann, B.: Ermittlung und Bewertung der Tonhaltigkeit von Schienenfahrzeuggeräuschen mit unterschiedlichen Verfahren. DAGA, Braunschweig, 2006.



Introduction Gear noise generation mechanisms

Gear mesh is major noise source

Reasons for structure-borne sound excitation

Parameter excitation due to stiffness variation

Displacement excitation due to flank deviation (e.g. caused by production process)

Within simulation, detailed consideration of

Varying gear mesh stiffness depending on rotation angle

Micro geometry of gears (flank deviation/flank modification)

Elastic deformation of gear mesh periphery (shafts, bearings, housing)



Introduction Simulation procedure (overall system approach)

Results :

dynamic excitation

in form of displacements on

bearing nodes

Results :

dynamic behaviour

in form of surface velocities of

gearbox housing

Results :

acoustical behaviour

in form of radiated sound

power and sound pressure



AGENDA

Who we are

Introduction




Conclusion



Simulation procedure Simulation of gear mesh excitation

Dynamic simulation using Software ROMAX-DESIGNER

Properties of simulation model

Detailed representation of gear mesh properties

Consideration of system deformation and their impact on gear mesh

Non-linear bearing models

Excitation of gear mesh is the only source of excitation

No consideration of excitations of other components (e.g. bearings)



Simulation procedure Numerical simulation of sound radiation

Simulation of surface velocities of the housing

Excitation from gear mesh calculation

Implementation in FE-model in form of displacement spectra at the bearing seats

Simulation of sound radiation

FE-fluid model of surrounding air

Infinite boundary condition on outer surface (free field condition)

Nonreactive excitation of fluid by calculated surface velocities

Calculation of emitted sound power and radiation characteristics

Bearing Seats



Simulation procedure Identification of critical operating points

Quick approximation of radiated sound power of the gearbox

𝑃𝑊 = 𝑍𝐿 ∙ 𝑆 ∙ 𝜎 ∙ 𝑣 2 with 𝑣 2 =1

𝑛 𝑣 𝑖

2

(assumptions for model comparisons: area 𝑆 = 1m2, radiation factor 𝜎 = 1)

Analysis of complete rpm-range to identify critical operating points

Consideration of discrete points on the housing surface

Sound power level for the first three harmonics of the gear mesh order



Simulation procedure Approximation of sound radiation

Approximation of the radiated sound for critical rotational speeds considering the averaged velocity and the area of all contributing surfaces

𝑃𝑊 = 𝑍𝐿 ∙ 𝑆 ∙ 𝜎 ∙ 𝑣 2 with 𝑣 2 =1

𝑆 𝑆𝑖𝑣 𝑖

2

(assumption: radiation factor 𝜎 = 1)

Analysis of frequency range up to 3 kHz (1st – 4th harmonics of the gear mesh order)

Error estimation by comparison with numerical simulation



AGENDA

Who we are

Introduction




Conclusion



Acoustical optimization Gear micro geometry optimization No macro geometry changes for acoustical optimization

(requirements from project partner)

Application of micro geometries / flank modifications to compensate

Displacements caused by the gear mesh periphery e.g. shaft deflections, housing deformation

Bias caused by the production process

Flank modifications used to lower system excitation (requirements from project partner)

Problem: Optimal dimensioning of flank modifications is not possible for all load cases due to a load dependency of the contact ratios.

involute barreling lead crowning lead slope



Acoustical optimization Gear micro geometry optimization

Parameter study (DoE) to optimize system excitation considering acoustical and durability aspects

Input parameters

Lead crowning (symmetrical)

Involute barreling (symmetrical)

Lead slope

Weighted target parameters

1st harmonic of the transmission error (TE) -> high weighting

2nd harmonic of the transmission error (TE) -> medium weighting

Contact pressure -> low weighting

con

tact

pre

ssu

re

Example of a 2-dimensional parameter study (involute barreling & lead slope)

Load distribution



high contributions

lowered contributions

structural modifications (e.g. ribbings)

change of surface contribution

Acoustical optimization Geometrical optimization of the gearbox housing

Structural optimization based on the different surface contributions

Lowering deflections of surfaces or shifting operational deflection shapes out of critical frequency ranges

Boundary conditions

Installation space specifications

No increase of overall mass



AGENDA

Who we are

Introduction




Conclusion



Simulation and optimization results Minor impact of structural optimization of gearbox housing (opt. model)

on noise radiation ( 2,4 dB)

mass and installation space restrictions lead to limited possibilities for significant noise reduction

High impact of micro geometry optimization (MGO) on noise radiation ( 5,6 dB)

Leads to a decrease of sound power over complete rpm-range (offset)

Consideration of shift of critical rotational speeds

Effects of the micro geometry parameter study detectable

Slight increase of the higher harmonics which does not affect the overall level (DoE target parameter 1st harmonic)



AGENDA

Who we are

Introduction




Conclusion



Conclusion

Objectives

System excitation optimization using micro geometry adjustments

Structural optimization of the gearbox housing

Results (for the analyzed gearbox)

Gear micro geometry optimizations have the highest noise reduction potential.

Structural changes on the gear housing have only minor impact on the sound radiation.

Reduction of the radiated sound power level up to 8 dB in the 1st harmonic of the gear mesh frequency possible



Thank you for your attention !

Jan Bräunig (Team Leader) Group Powertrain and Gearbox Acoustics

Fraunhofer Institute for Machine Tools and Forming Technology (IWU) Nöthnitzer Straße 44 01187 Dresden Germany Phone +49 351 4772-2321 Fax +49 351 4772-2303 [email protected]

Manuel Haase Group Powertrain and Gearbox Acoustics

Fraunhofer Institute for Machine Tools and Forming Technology (IWU) Nöthnitzer Straße 44 01187 Dresden Germany Phone +49 351 4772-2797 Fax +49 351 4772-2303 [email protected]

mailto:[email protected]

mailto:[email protected]

acoustical optimization of a train gearbox based …group powertrain and gearbox acoustics...

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