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flanging noise Challenges in validation of friction management in - - PowerPoint PPT Presentation

May 05, 2023 309 likes •636 views

Wheel squeal and flanging noise Challenges in validation of friction management in the field and laboratory Dr. J.Paragreen - LB Foster 30 th June 2020 LB Foster / Our Vision 1 Contents Background to rail-wheel noise Wheel squeal

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LB Foster / Our Vision

Wheel squeal and flanging noise

Challenges in validation of friction management in the field and laboratory

  • Dr. J.Paragreen - LB Foster

30th June 2020

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Contents

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 Background to rail-wheel noise  Wheel squeal field trials  Theory behind wheel squeal  Laboratory testing  Summary of challenges

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Friction Management – Guiding Principles

 Gau Gauge Face ace (GF) (GF) / / Whee heel l Fl Flan ange lub ubric icatio ion TARGET: COF < 0.15  Impacts:

  • Rail / Wheel Wear
  • Gauge Corner Cracking
  • Flange Noise
  • Derailment Potential (Wheel Climb)

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 Top

  • p of
  • f Ra

Rail (T (TOR) OR) / / Whe heel Trea ead Fri Frictio ion Mo Modi difie fier TARGET: COF ~ 0.35  Typical dry 0.6  Impacts:

  • Rail / Wheel Wear
  • RCF Development
  • Top of Rail Noise
  • Corrugations

 Reduced lateral forces  Switch protection  Reduced traction energy consumption

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Background to rail wheel noise

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Noise: Spectral ranges

Noise Type Frequency range [Hz]

Rolling 30 – 2500 Rumble (including corrugations) 200 – 1000 Flat spots 50 – 250 (speed dependant) Ground Borne Vibrations 30 – 200 Top of rail squeal 1000 – 5000 Flanging noise 5000 – 10000

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Human perception of noise

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Top of rail wheel squeal noise

  • High pitched, tonal squeal (predominantly 1000 – 5000 Hz)
  • Prevalent noise mechanism in “problem” curves, usually < 300m

radius

  • Related to both negative friction characteristics of Third Body at

tread / top of rail interface and absolute friction level ➢ Stick-slip oscillations ➢ Leading wheelset, inside wheel

Flanging noise

  • Typically a “buzzing” OR “hissing” sound, characterized by

broadband high frequency components (>5000 Hz)

  • Affected by:

➢ Lateral forces: related to friction on the top of the low rail ➢ Flanging forces: related to friction on top of low and high rails ➢ Friction at the flange / gauge face interface

Squeal and Flanging Noise

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Corrugation noise

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Corrugation noise

  • Low pitched rumbling noise due to the

presence of corrugation on the running band

  • f the rail

Noise due to corrugation with occasional wheel squeal and flanging noise

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Field trials

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Baseline – No No TOR FM application

FM Focus: Noise/Corrugation

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AFTER TOR FM application - manual

FM Focus: Noise/Corrugation

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Spectral sound distribution: Trams

 Effects of frictional conditions

0.0 20.0 40.0 60.0 80.0 100.0

12.5 31.5 80 200 500 1250 3150 8000 Frequency (Hertz)

Sound Level (dBA) Baseline Friction Modifier

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Spectral sound distribution: Trams

 Effects of frictional conditions

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Field trials

 Typical field trials compare baseline measurement to application of top of rail materials  Noise can be very specific to:

  • Vehicle
  • Bogie steering – primary yaw stiffness
  • Wheel profile
  • Location – curve/cant
  • Running speed
  • Weather
  • Rain and moisture (morning dew) particularly large impacts
  • Humidity
  • Rail and wheel contamination
  • Measurement location (reflections)

 Don’t necessarily get squeal from every bogie

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Wheel squeal – conventional theory

Lateral creepage of the wheel - prime cause of squeal

  • Particularly for the leading inner

wheel of a bogie

  • stick-slip mechanism of this

creep force

Rudd 1976, Remington 1985

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AOA

Wheel lateral creep direction

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Absolute Friction Levels and Positive/Negative Friction – conventional theory

0.00 0.10 0.20 0.30 0.40 0.50 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

Creep Rate (%) Y/Q

* Replotted from: “Matsumoto a, Sato Y, Ono H, Wang Y, Yamamoto Y, Tanimoto M & Oka Y, Creep force characteristics between rail and wheel on scaled model, Wear, Vol 253, Issues 1-2, July 2002, pp 199-203.

Negative friction Positive friction

Dry Contact Friction Modifier

Stick-slip limit cycle

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Absolute Friction Levels and Positive/Negative Friction – conventional theory

+ + +

  • Creepage / friction force

Frequency response of the wheel

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Alternative theory

Mode Coupling In Instability Mechanism

 Jiang, Anderson and Dwight, 2015  Further analysis by Bo Ding 2018

Theory:

 Based on commonly accepted theory for squeal in braking

  • systems. A coupling of vibration in two different directions

 Wheel/rail interface subject to vertical and lateral vibrations and forces

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Alternative theory

Mode Coupling In Instability Mechanism

 The lateral frictional force between the wheel and the rail is related to the normal (vertical) force, so a natural coupling  𝐺 = 𝜈𝑂  If wheel vertical and lateral vibration frequency modes are close  Then friction coefficient increases to a critical threshold,

  • > vertical and lateral oscillations become out-of-phase
  • > friction force, which depends on the vertical force, is

therefore out-of-phase with the lateral motion => unstable positive feedback.

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Alternative theory

Mode coupling instability mechanism

 Curley, Anderson, Jiang and Hanson – track study

  • Found noise from wheels on inner and outer rail
  • Running bands in different locations on gauge corner of inner and outer rail
  • Track form had an influence
  • Found TOR FM had benefit when applied to both rails, but in some cases when

applied to inner rail only no benefit

  • Counter to normal theory gauge corner lubrication also had a benefit for wheel

squeal

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Alternative theory

Mode coupling instability mechanism

 For all these theories friction between the wheel and the rail still key.

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 Work carried out by Bo Ding 2018 – studied slip/stick mechanism, mode coupling instability, and third potential mechanism wheel rail coupling  2 point contact – not studied much wrt wheel squeal

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Freight trial with two types of water based TOR FMs

 Two versions of top of rail friction modifiers tested

  • Both products have high positive friction characteristics
  • Similar intermediate friction
  • Different binders and tackiness
  • One product retained more on wheel (less effective),
  • ther transferred more to rail
  • One product much more effective than the other in

noise reduction  Oil and grease based top of rail materials – difficult to balance noise reduction with braking and traction performance  Difficult to predict noise performance from laboratory testing

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Laboratory investigations into wheel squeal

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Laboratory testing

 Twin disc type testing

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  • Eg. TNO test rig
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Laboratory testing

 Scaled rigs

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Laboratory testing

 Full scale test rigs

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  • Eg. DB full scale test rig
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UIC study 2005

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Comparison of wheel squeal for different FMs in lab and in the field – (Y – Noise reduced, N – no significant noise reduction)

 Compared results wheel squeal mitigation of different products on laboratory test rigs and on site measurements

  • Issue of application rate, too

TOR FM1 (water based) TOR FM2 (oil based) TOR FM3 (oil based) TOR FM4 (oil based) Water TNO rig Y Y Y Y DB rig Y Y Y Site 1 Y N N N Site 2 N Site 3 Y Y Field Lab

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Wheel squeal mitigation

 Good understanding of effective mitigation methods

  • Top of rail/tread friction modifiers (lubrication) – all

theories point to the importance of friction control

  • Bogie/wagon design
  • Distance between axles
  • Vehicle steering – primary yaw stiffness
  • Wheel dampeners
  • Wheel and rail profile
  • Track form dynamics

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Challenges

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Product development

 Need on track trials and case studies to prove noise reducing properties.  Lab scale test can give an indication – but not the whole story

  • Slows down product development – need to produce larger

batches

  • Some products are easier to test by manual application than
  • thers
  • Eg on board - solid stick friction modifiers and lubricator sticks
  • to test in the field do you swap out the sticks from the

whole fleet to negate the effect of other sticks on the performance? – In a smaller limited trial do you build up sufficient film thickness  Need for better lab scale noise testing  Understanding of required film thickness/application rate

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End customer

 Needs case studies and evidence of on track performance  Cannot rely on lab tests and friction data alone  Squeal/noise remains a major issue for most railways/metros

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“curve squeal remains one of the least understood railway noise sources despite the continuing efforts over recent decades” Jiang, Anderson and Dwight, 2015

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Questions

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