Harmonic Vehicle/Track Interaction: Using Simulation Tools to - - PowerPoint PPT Presentation

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Harmonic Vehicle/Track Interaction: Using Simulation Tools to Increase Train Speeds and Safety Assurance Raphael Marotta Lucas Valente 1 MRS Logistic in Brazil MRS Logstica is a concessionary that controls, operates and monitors the

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Harmonic Vehicle/Track Interaction: Using Simulation Tools to Increase Train Speeds and Safety Assurance Raphael Marotta Lucas Valente

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MRS Logistic in Brazil

MRS Logística is a concessionary that controls, operates and monitors the Southeastern Federal Railroad Network. The company has been in operation in cargo railway transportation since 1996 Across the rails, connect the three main economic centers of Brazil: Rio de Janeiro, Minas Gerais and São Paulo.

MRS’ Shareholders

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Why a presentation on harmonic excitations?

  • Some derailments are related with harmonic

excitations.

  • Operation’s need to increase speed in many

sections of MRS track safely.

  • Case: Derailment with a GHS (Gondola‐Hopper)

wagon with worn truck conditions.

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Methodology developed to analyze the vehicle dynamic behaviour taking in account the MRS’s features of vehicles, track and operation.

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  • A vibratory system will have energy dissipated

when

  • scillating
  • nly

under an initial disturbance.

  • An external force must be applied to maintain

an

  • scillation

motion, such as: harmonic, nonharmonic, transient or random.

  • Resonance is a harmonic excitation, when the

frequency of excitation coincides with the natural frequency of the system. In a railway track irregularities are harmonic motion of the base

What is a resonance phenomenon ?

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1 2 1   f f fr

Resonance Natural frequency Excitation frequency

Single degree

  • f freedom

What is a resonance phenomenon ?

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The lower sway is a combination between rolling and lateral oscilation.

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Carbody modes

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Carbody modes

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  • The lower sway motion is related to the cross level irregularity.
  • The harmonic instability occurs when the excitation frequency is near to the

carbody natural frequency of sway mode.

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Lower sway

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  • Eingenvalue method
  • Although the freight car is suspension is non‐linear, this analysis allows to

examine and understand about the carbody mode. The result is the free response of the system.

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Frequency Mode fn(Hz) ζ fd(Hz) 1 Lower sway

fLS

LS

fLS

2 Yaw

fY

Y

fY

3 Bounce

fB

B

fB

4 Pitch

fP

P

fP

5 Upper sway

fUS

US

fUS

Vehicle modal analysis

fn: Natural frequency ζ: Damping factor fd: Natural frequency

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Speed (km/h) Wavelength (m)

Wavelength vs Speed

Lower Sway Yaw Bounce Pitch Upper Sway

Harmonic combination

Connecting speed, frequency and wavelength, thus:

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  • Transient method
  • An external force is applied in the carbody center of gravity.
  • 2 simulations were performed, one with friction wedges(damping natural

frequency) and the other without(natural frequency). Natural frequency Vehicle oscillation

Lower sway frequency

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Lower sway frequency

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Geometry data processing

Strip Chart (Cross level)

  • After modal analysis it is necessary

identify the λ from geometry data provided by the TrackSTAR

  • It is usual to apply Signal Processing

Tools for this purpose

Geometry Data

‐4 ‐2 2 4

Km

Defect amp

 v f 

Wagon Speed Track Wavelenght

Excitation frequency

v=λf v=λf

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Geometry data processing

‐2 2 ‐2 2 ‐5 5 ‐2 2 ‐3 ‐2 ‐1 1 2 3

1 2 3 4

‐6 ‐4 ‐2 2 4 6

Geometry data sample

Sin (0.02πx) 1.5 Sin (0.04πx)

2.5 Sin( 0.08πx +0.5)

Sin (0.16πX)

f(x) = sin (0.02πx) + 1.5 sin (0.04 πx) + 2.5sin (0.08 πx + 0.5) + sin (0.16 πx)

  • The geometry data is defined as a sum of sines and cosines
  • λ is determinated using the Fast Fourier Transform method

PSD An alternative way to represent track geometry

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Geometry data processing

P O W E R Frequency Expected behavior of a PSD

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Geometry data processing

  • With the modal analisys completed, the next step is to

determine the frequency bands of interest.

  • Upper and Low frequency limits must be defined.
  • Determinate power within the frequency band.
  • A higher power level correspond to most likely

resonance.

  • Diagnosticate risk areas ( mile post) and confirm the

diagnosis through simulation. What do we need to identify if the resonance phenomenon occurs?

Track Inspetion Input data Geometry data processing Modal Analisys Simulation Simulation

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Geometry data processing

FREQUENCY POWER Km Post POWER

UPPER LIMIT LOW LIMIT Power within the frequency band

Frequency band

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Mass Wheelset Spring Friction elements Non linear stiffness Main vehicle modeling elements in VAMPIRE Stiffness elements

Simulation – Vehicle Modeling

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Main track modeling elements in VAMPIRE

Shoulder Shoulder Tie Tie Rail and Fasntenings Rail and Fasntenings Suballast Suballast Foundation Foundation Ballast

Vertical Stiffness

  • Track Modulus – Field Instrumentation,

Track Inspection Vehicle.

Lateral Stiffness

  • Rail to tie – TrackSTAR
  • Tie to ballast – STPT, Tamping

Machines.

Simulation – Track Modeling

Geometry – Track Geometry Car

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Case – GHS derailment

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  • Vehicle GHS 100 tons with Ride Control 6” x 11” truck.
  • High conicity wheel profile.
  • Center of gravity height: 2.21 m.
  • Block side bearing.
  • Constant damping with worn wedges.
  • 62 degree‐of‐freedom.

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Note: Friction wedges in worn conditions due to failure in the manufacturing process

GHS – Vehicle Modeling

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  • Eingenvalue method results:

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Frequency Mode fn(Hz) ζ fd(Hz) 1 Lower sway 0.94 0.04 0.94 2 Yaw 2.42 0.14 2.40 3 Bounce 2.46 0.07 2.45 4 Pitch 3.28 0.09 3.27 5 Upper sway 4.44 0.18 4.37

Vehicle modal analysis

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  • Transient method results:

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0.88 Hz

Lower sway frequency

0.83 Hz

Natural frequency Damping natural frequency

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40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 Speed (km/h) Wavelength (m)

Wavelength vs Speed

Lower Sway Yaw Bounce Pitch Upper Sway

Harmonic combination

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λ = 24 m Low stiffness Low stiffness If the rail or welds joints were applied in a alternating way the λ will be 12 m

  • CWR length at MRS – 240 m
  • Bar length – 24 m
  • The wavelength is more or less the same

CWR length due the low stiffiness region

Harmonic combination

Dominant Component Wavelength (m) Parameter Affected Ballast 50 Vehicle (Comfort) 20 10 5 Rail 2 Dynamic forces (Track deterioration) 1 0.5 0.05

Mode fn(Hz) Lower sway 0.94 Yaw 2.42

2.42

λyaw = 5.72 m

50 km/h

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No geometry exceptions MAXIMUM DEFECTS AMPLITUDES Surface – 10 mm Alignment 12 mm Cross level – 17 mm Gauge – 20 mm

Visually the cross level wavelengths seems to be about 20 m. It’s necessary to investigate more deeply

Track geometry at derailment site

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Track Geometry Analysis

Km Post

UPPER LIMIT = 0.05 Hz LOW LIMIT = 0.06 Hz

Frequency band

From the modal analysis

Damping natural frequency ‐ 0.83 Hz Natural frequency ‐ 0.88 Hz Frequency band lower sway 0.83Hz to 0.88Hz

f v .  

Wagon Speed 50 km/h Natural frequency 0.83Hz to 0.88Hz

λ = 15m ‐ 16 m

f = 1/ λ f = 0.05Hz – 0.06Hz

Likely site for harmonic behavior Likely sites to find a harmonic behavior

FREQUENCY POWER POWER

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Vampire Pro TRANSIENT ANALYSIS VAMPIRE Plot

13 abr 2016 16:47:28 Axle 1 left wheel Unloading Axle 1 right wheel Unloading Axle 3 left wheel Unloading Axle 3 right wheel Unloading

100 200

  • 100
  • 50

50 100 m percent

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  • Wheel unloading results:

40 km/h

Vampire Pro TRANSIENT ANALYSIS VAMPIRE Plot

13 abr 2016 16:48:25 Axle 1 left wheel Unloading Axle 1 right wheel Unloading Axle 3 left wheel Unloading Axle 3 right wheel Unloading

100 200

  • 100
  • 50

50 100 m percent

50 km/h

Simulation results

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Results reached through simulation

Speed Gains 2015

Location Speed Gain Car type Ferrovia do Aço 50 64 Gondola Paraopeba 30 40 Fuel tank car Paraopeba 40 50 Cement tank car

Vale Paraíba 50 64

  • L/V
  • Hunting
  • Harmonic Behavior
  • Longitudinal Dynamic

Ferrovia do Aço Paraopeba

STEPS TO INCREASE SPEED SAFELY

  • After the derailment at Vale do Paraiba, the

harmonic behavior is taken into account to increase train speeds at MRS.

  • No derailments related to harmonic behavior

since 2013 !

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  • Harmonic excitation analysis is an important step to increase speed safely.
  • Multibody simulations can be applied to support new operation

conditions.

  • The simulations can reduce cost and time in instrumentation field tests, if

necessary.

  • The methodology presented is applicable for any vehicle, speed, and

carbody modes.

Conclusions

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Questions ?

Raphael Marota raphael.marotta@mrs.com.br Lucas Valente lucas.valente@mrs.com.br