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How vehicle dynamics can be used

• Tender of new vehicles

  • Suggest the best design for the customer
  • Check that it is possible to fulfill required standards
  • Check that the customer's demands are reasonable

• Design of new vehicles

  • Make sure that the required standards are fulfilled:
    safety, derailment, wheel unloading, track-shift forces,,, etc.
  • Make sure that the customer's demands are fulfilled:
    comfort, wheel/rail wear, RCF,,, etc.
  • Calculate dynamic forces acting on the structure for estimation of fatigue
  • Calculate eigen values
  • Calculate critical speeds for different conicities
  • Calculate max dynamic motions of the vehicle (Gauging)
  • Writing purchase requests for suspension components
  • Test the suspension components at tolerance limits
  • Test what will happen if there is a failure in one or more of the suspension components
  • Test the vehicle under different wheel/rail-friction conditions
  • If the vehicle has friction dampers. Test what will happen under very low and very high coefficient of friction.

• Re-building existing vehicles

  Is very similar to "Design of new vehicles". However the designer is not as free as in a design of a new vehicle.

• Track design

  • Study different shapes of transition curves
  • Choose the optimum length of a transition curve
  • Optimization of wheel/rail geometries

• Mechatronics systems

  • Test where to apply the controlling force and/or moment
  • Testing of different control strategies
  • Choose where to measure displacements, velocities, accelerations ,,,etc.

• Special cases

  • Wave propagation in long trains with consideration taken to the topography of the track
  • Passing a turnout with consideration taken to the change of the rail profile through the curve
  • Education and research

• Test of emergency situations

  • Passing a curve at overspeed
  • Wind loads including wind gusts
  • Running through a turnout in wrong direction
  • Apply maximum track error in the worst place in a curve
  • Etc.

Requirements on railroad vehicles

• Wheel unloading

  • Risk of flange climbing, static criterion

• Y/Q-quotient

  • Risk of flange climbing, dynamic criterion

• Overturning safety

  • Risk of overturning in curves
  • Risk of overturning due to wind gusts

• Lateral track-shift forces

  • Destroys track alignment
  • Widens the gauge
  • Risk of rail rollover

• Max critical speed

  • For different conicities and friction conditions
  • Must be calculated in a non-linear model
  • Damping of the kinematic mode at max service speed

• Sway motions

  • Pantograph motions
  • Gauging

• Wheel/rail wear

  • Estimate travelled distance before reprofiling
  • May change the profiles into an unfavorable shape

• Accelerations, jerk and roll speed

  • Ride comfort evaluations

• RCF Rolling Contact Fatigue

  • Initiates cracks in wheel and rail