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FORCE-BASED ASSESSMENT OF WELD GEOMETRY

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

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FORCE-BASED ASSESSMENT OF WELD GEOMETRY

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  1. FORCE-BASED ASSESSMENTOFWELD GEOMETRY Coenraad Esveld Delft University of Technology Esveld Consulting Services

  2. DAMAGE DUE TO POOR WELD GEOMETRY

  3. EXISTING WELD GEOMETRY STANDARDS Grind off top p < 0.3 mm For example Versine: 0 < p < 0.3 mm

  4. VELOCITY APPROACH The dynamic contact force as a function of the first time derivative:

  5. QUALITY INDICES (QI) • QI ≤ 1: Accepted • QI > 1: Rejected

  6. FORCE-BASED STANDARDS Conventional Implemented in RAILPROF Total force in principle 225 kN HSL HH QI=1

  7. 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.

  8. LATERAL GEOMETRY STANDARDS Implemented in RAILPROF QI=1

  9. ASSESSMENT OLD AND NEW ON PRORAIL RP002949 RP002949 RP002432 RP002432 Old norm: Rejected, New: OK Old norm: OK, New: Rejected RP003125 RP003125 RP002945 RP002945 Old norm: Rejected, New: OK Old norm: Rejected, New: Rejected

  10. SELECTION ON PRORAIL 100 welds per group 1.8 mrad (140 km/h) Limit at 80 km/h

  11. OLD VERSUS NEW STANDARDS

  12. CALCULATED DYNAMIC FORCES Low correlation force and versine High correlation force and QI

  13. CALCULATED DYNAMIC FORCES Dynamic force linear with QI Dynamic force linear with train speed

  14. Dynamic amplification less than 2.2 AXLE BOX ACCELERATIONS

  15. 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 < 1: OK, otherwise: grinding.

  16. PRACTICAL IMPLEMENTATION

  17. PDA SCREEN V = 140 km/h QI = 1.06 QI uniquely shows where to grind

  18. All data and graphs can be shown on a PC; • Results in pdf-format can directly be emailed to customer. DESKTOP SOFTWARE

  19. 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.

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