quiet-track: track optimisation and monitoring for further ... · optimisation and monitoring for...

QUIET-TRACK: Track

optimisation and monitoring

for further noise reduction

dr.ir. Geert Desanghere

Akron, Belgium

[email protected]

www.akron.be

mailto:[email protected]

Quiet-Track: EU-project: Consortium

QUIET-TRACK: Track optimisation and monitoring for further noise reduction 2


1 Monitoring of rail roughness, track dynamic properties and average wheel roughness

1.1 Monitoring of rail roughness

1.2 Monitoring of track decay rate

1.3 Investigation of Track Decay Rates (TDR) of embedded rails

1.4 Average wheel roughness determination

2 Rolling contact model enhancement in the existing rolling noise models

2.1 Rolling contact model enhancement

2.2 Model for low frequency noise emission

3 Concepts and tools for noise related track maintenance

3.1 Concepts for acoustic rail grinding

3.2 Concepts for rail profile correction

3.3 Development of a noise related track maintenance tool

Work packages


4 Development and validation of high performance solutions for reduction of track related noise

4.1 Combination of existing track solutions

4.2 Innovative solutions based upon reduced rail roughness growth rate

4.3 Acoustical embedded rail

4.4 Rail type and hardness selection for optimal acoustic performance and wear

5 Development of noise management tools

5.1 Procedure for performance measurement of mitigation measures

5.2 Noise management tool for track maintenance activities

5.3 Noise management tools for noise mitigation solutions at the track level

Work packages

• W/R NOISE program:

– is a further development of the original wheel-rail noise emission models developed by Paul Remington

– further developed than TWINS

– includes the possibility to import measured track and wheel impedances (horizontal, vertical and cross) or calculated impedances by a very precise dynamic finite element model.

– source code of W/R Noise in Matlab,

• Enhancement:

– introduction of realistic multi-point wheel-rail contact conditions in curves (and in some worn tangent track sections).

– existing models use a Hertzian single point contact with a roughness wavelength filter which is only related to vehicle speed and not to the real wheel-rail contact conditions which are influenced by rail wear, curving, presence of defects.

Modelling Enhancement:

New multi-point W/R contact model



• Validation:

a complete numerical noise analysis with the enhanced W/R Noise model or

two selected reference track systems.

– a tangent track with discretely supported rails on sleepers in a ballasted

bed

– a similar curved track,

– considering the same vehicle at the same speed and the same rail type.

• input parameters for the noise calculations will be measured: TDR’s, rail

roughness and average wheel roughness.

• track and wheel impedances will be measured and computed.

• rail profiles (influencing the wheel-rail contact conditions) will be measured.

The numerical results obtained with the different sets of input parameters will

be compared with measured pass-by noise measurement results.

Modelling Enhancement:

New multi-point W/R contact model


• Procedure for calculating the low frequency noise emission below 250 Hz and propagation

– based on the use of deterministic models (acoustic finite elements and boundary elements).

– will be integrated as a specific module within the enhanced W/R Noise software.

• Validation:

A complete numerical noise analysis below 250 Hz with acoustic boundary element analysis and above 250 Hz with the existing W/R Noise software will be carried for two selected reference track systems

– one embedded track

– one track with discretely supported rails on sleepers in a ballasted bed,

– same approach

– compared with measured pass-by noise measurement results.

Modelling enhancement:

Model for low frequency noise emission


• Normal rolling noise on straight track

– Absence of wheel and rail imperfections or discontinuities leading to

impact noise (wheel flats, rail joints, …)

– No curving noise (squeal)

• Primary generating mechanism

– Wheel and rail roughness

• Broadband frequency spectrum

– 250 to 5000 Hz

Existing Wheel-Rail software


• Analytical model

– Developed by Remington

– Modified to include lateral rail radiation

Structure of the W/R program


• Roughness: roughness on wheel and rail running surfaces: w and r

• Contact stiffness: to account for local deformations of wheel and rail

under vertical load (FV): KCR and KCW

W/R Noise Software:

Wheel / Rail interaction

RHWA

CRVCWVRVWR

YY

KFrKFwYY

//

Displacements at the point of contact

Derivation

Velocities at the point of contact

RHRVWAWR YYYY....

, , ,

Definition of wheel & rail impedance


• Definition of wheel and rail impedance [N/ m/s]

– Wheel

• Radial impedance: ZWR

• Axial impedance: ZWA

• Cross-impedance: ZWVH

– Rail

• Vertical impedance: ZRV

• Horizontal impedance: ZRH

• Cross-impedance: ZRVH

W/R Noise Software:

Wheel / Rail interaction

RHHRVHVRH

RVVRV

RHWAHWVHVWA

WRVWR

ZFZFY

ZFY

YZFZFY

ZFY

//

)/(

//

/


• Vehicle characteristics

– Light rail car

• 6 axles

• 60 tons

– Speed : 50 km/h

• Track characteristics

– Girder rail NP 4 am

– Rail directly fastened every 60 cm to a concrete slab

– A pavement allows the rail to radiate only in the vertical direction

• Measurement

– Distance: 7.5 m from track centerline

W/R Noise Software:

Example: description of a test site


• Roughness of wheel and rail running surfaces

– Typical roughness spectra

• Trued wheel

• Welded rail

• Total contact stiffness

– Wheel and rail material

• Elasticity modulus

• Poisson ratio

– Wheel and rail geometry

• Radius of curvature

– Vertical load forcing the wheel against the rail

W/R Noise Software:

Wheel / Rail interaction at test side

Roughness spectra (50km/h)

___ wheel ___ rail


• Contact area filter

– Degree of transverse correlation

• Hypothesis: wheel and rail

roughness are well correlated for

two parallel paths in the direction

of rolling

High degree of transverse

correlation

– Contact area radius

• Hertz theory

W/R Noise Software:

Wheel / Rail interaction at test site


• Rail impedance (vertical, horizontal, cross)

– Measurement of the vertical impedance on

the test track

– Development of a finite element model of

the test track

– Tuning of the model by comparing

measured and calculated vertical

impedance

– Calculation of the horizontal impedance

and cross-impedance

W/R Noise Software:

Rail behaviour (example)

Deformation 1700Hz

Vibration sensor

Load sensor


• Rail impedance - Results

– Comparison between measured

and calculated vertical

impedance

– Calculated horizontal and cross-

impedance

W/R Noise Software:

Rail behaviour (example)

Admittance = 1 / Impedance

___ horizontal

___ vertical

___ cross – calculated

___ vertical -

measured


• Measurements on the track

– Vertical and lateral excitation on

the rail with an impact hammer

– Measurement of the rail vibration

at different points in vertical and

lateral direction

– => Vertical and lateral rail

vibration spectra at various

distances from the point of

excitation

W/R Noise Software:

Track decay rate (test site)

Point of excitation

Impact

hammer

1m

1m

Vibration

sensors


Example: Decay of vertical rail vibration for each frequency band

W/R Noise Software:

Track decay rate (example)

-2dB/m

-4dB/m


• Wheel impedance

(radial, axial)

– Measurements on a wheel of the

test vehicle

• Radial or axial excitation on the

wheel with an impact hammer

• Measurement of the wheel

vibration in radial or axial

direction

• => Measured radial and axial

admittance

W/R Noise Software:

Wheel behaviour (example)

___ axial ___ radial


• Sound radiation

– Average vibration response

– Radiating areas

– Radiation efficiencies

• Wheel: radial or axial

• Rail: vertical

• Sound propagation

– Ground reflections

• Sound level cancellation at wavelengths equal to twice the path length difference

• At higher frequencies (> 250Hz)

– Direct sound and reflected sound tend to add as incoherent sources and thus increase the sound level

– A ground effect term is introduced in the propagation equations

W/R Noise Software:

Sound radiation and propagation

___ wheel ___ rail


• Metro vehicle

– A reference metro vehicle has also been selected and its characteristics have been used to define the reference values of the input parameters.

– This reference vehicle is composed of six cars of 18,2 m each and is partly illustrated in figure below.

W/R Noise Software:

Sensitivity Analysis

Parameter Reference value Alternatives

Length of the vehicle [m] 109 -

Number of axles 24 - Axle load [T] 12 10 – 11 – 13 – 14

Vehicle speed [km/h] 80 60 – 100 Type of wheel solid wheel -


W/R Noise Software:

Wheel roughness


W/R Noise Software:

Data related to the track

Parameter Reference value Alternatives

Sleeper

Elasticity modulus [MPa] 18 000 -

Poisson’s ratio 0,3 -

Density [kg/m³] 1 000 -

Loss factor [%] 8 -

Dimensions [mm] 2 600 x 240 x 140 -

Distance between sleepers [m] 0,60 -

Ballast

Loss factor [%] 60 -

Dynamic stiffness [kN/mm/sleeper] 25 -

Rail

Type RATP 52 EB50T, Np4am, 35G

Loss factor [%] 2 -

Rail pad

Loss factor [%] 25 10 – 50

Dynamic stiffness [kN/mm] 150 -


W/R Noise Software:

Finite Element Model


W/R Noise Software:

Results

Sleeper Rail Wheel TOTAL

Vehicle speed60km/h 68,25 73,23 73,90 77,18

80km/h 71,92 77,84 77,86 81,38

100km/h 74,48 81,10 81,01 84,52

Axle load10T/axle 72,15 78,23 78,29 81,77

11T/axle 72,03 78,03 78,06 81,57

12T/axle 71,92 77,84 77,86 81,38

13T/axle 71,80 77,65 77,67 81,20

14T/axle 71,69 77,48 77,49 81,03

Rail pad loss factor10% 74,36 80,62 77,77 83,07

25% 71,92 77,84 77,86 81,38

50% 70,21 75,96 78,00 80,53

Wheel and rail roughnessRail A Wheel B -5dB 65,15 71,30 71,23 74,78

Rail B Wheel B -5dB 66,92 72,84 72,86 76,38

Rail A Wheel B 69,41 75,68 75,55 79,12

Rail C Wheel B -5dB 70,04 75,72 75,85 79,34

Rail B Wheel B 70,15 76,30 76,23 79,78

Rail C Wheel B 71,92 77,84 77,86 81,38

Rail D Wheel B 75,04 80,72 80,85 84,34

Rail C Wheel B +5dB 75,15 81,30 81,23 84,78

Rail D Wheel B +5dB 76,92 82,84 82,86 86,38

Rail E Wheel B 79,23 84,75 84,95 88,42

Rail E Wheel B +5dB 80,04 85,72 85,85 89,34

Rail F Wheel B 83,94 89,40 89,62 93,09

Rail F Wheel B +5dB 84,23 89,75 89,95 93,42

Rail typeEB50T 71,89 77,77 77,84 81,34

RATP52 71,92 77,84 77,86 81,38


W/R Noise Software:

Results

Parameter Parameter giving the

lowest noise level

Parameter giving the

highest noise level

Variation of rolling

noise in dB

Vehicle speed 60 km/h 100 km/h 7,3

Axle load 10 T 14 T 0,7

Rail pad loss factor 50% 10% 2,5

Wheel or rail roughness Smooth Rough 15

Type of rail EB50T RATP 52 0,04


W/R Noise Software:

Results

Parameter Parameter giving the

lowest noise level

Parameter giving the

highest noise level

Variation of rolling

noise in dB

Vehicle speed 80 km/h 160 km/h 9,4

Axle load 12 500kg 5 000kg 1,1

Track type “Bi-block” Holz 3,1

Rail pad loss factor 50% 10% 2,6

Wheel roughness Smooth Rough 8,5

Rail roughness Smooth Rough 3,9

Type of rail UIC 54 E UIC 60 0,7

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