College e51 Inleiding Railbouwkunde

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FORCE-BASED ASSESSMENTOFWELD GEOMETRY
Coenraad Esveld
Delft University of Technology Esveld Consulting
Services
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DAMAGE DUE TO POOR WELD GEOMETRY
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EXISTING WELD GEOMETRY STANDARDS
Grind off top
p lt 0.3 mm
For example Versine 0 lt p lt 0.3 mm
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VELOCITY APPROACH

• The dynamic contact force as a function of the
  first time derivative

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QUALITY INDICES (QI)

• QI 1 Accepted
• QI gt 1 Rejected

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FORCE-BASED STANDARDS
Conventional
Implemented in RAILPROF
Total force in principle 225 kN
HSL
HH
QI1
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NEW VERSUS OLD NORM
For 80 km/h the new norm is 2.4 times more
favorable than the old norm, provided short waves
have been ground off.
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LATERAL GEOMETRY STANDARDS
Implemented in RAILPROF
QI1
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ASSESSMENT OLD AND NEW ON PRORAIL
RP002949
RP002949
RP002432
RP002432
Old norm Rejected, New OK
Old norm OK, New Rejected
RP002945
RP002945
RP003125
RP003125
Old norm Rejected, New OK
Old norm Rejected, New Rejected
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SELECTION ON PRORAIL
100 welds per group
1.8 mrad (140 km/h)
Limit at 80 km/h
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OLD VERSUS NEW STANDARDS
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CALCULATED DYNAMIC FORCES
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CALCULATED DYNAMIC FORCES
Low correlation force and versine
High correlation force and QI
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CALCULATED DYNAMIC FORCES
Dynamic force linear with QI
Dynamic force linear with train speed
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AXLE BOX ACCELERATIONS
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PRACTICAL IMPLEMENTATION

• Procedure
• Sample weld geometry with digital straightedge
• Filter measured signal
• Determine 1st derivative (inclination)
• Normalize with intervention value for line speed
• Calculate QI.
• QI lt 1 OK, otherwise grinding.

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PRACTICAL IMPLEMENTATION
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PDA SCREEN
V 140 km/h QI 1.06
QI uniquely shows where to grind
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DESKTOP SOFTWARE
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CONCLUSIONS

• 1. Theory based on first derivative works fine in
  practice
• 2. Steel straightedge is absolutely inadequate
• 3. Instead electronic straightedges with QI
  (RAILPROF)
• High correlation of force and QI, low correlation
  with versine
• With RAILPROF QI measurement
• You see what you do
• Higher quality
• Less rejections provided short waves are ground
  properly (also negative welds allowed)
• Extension of life cycle.