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How vehicle dynamics can be used

• Tender of new vehicles
• • Suggest the best design for the customer Example
  • Check that it is possible to fulfill required standards
  • Check that the customer's demands are reasonable
  • Calculate the price
• 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.
  • Considerations must be taken to the curve distribution of customers track
  • If customer requirements are not met, the manufacturer may suffer from delivery penalties
  • Calculate dynamic forces acting on the structure for estimation of fatigue
  • Calculate eigenvalues, to avoid that different eigenfrequencies coincide
  • 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 friction coefficients.
• Re-building existing vehicles
• Very similar to Design of new vehicles, but the designer is not as free as in a design of a new vehicle. However there is an advantage with modifying existing, because in this case the vehicle designer has the possibilities to validate the model with the existing vehicle.
• Track design
• • Study different shapes of transition curves
  • Choose the optimum length of a transition curve
  • Optimization of wheel and/or rail profiles
• Mechatronic systems
• • Test where to apply the controlling force and/or moment
  • Testing of different control strategies
  • Choose where to measure displacements, velocities, accelerations ,,,etc.

  Example of mechatronic system: Tilt mechanism, Skyhook damper

• Special cases
• • Wave propagation in long trains with consideration taken to the topography of the track Example
  • Passing a turnout with consideration taken to the change of the rail profile through the curve Example
  • 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. etc.

Acceptance tests

• Wheel unloading on twisted track
• • 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

    Calculation of critical speed:

    
    

    Limit cycle diagram:

    
    
• Dynamic motions
• • Pantograph motions
  • Gauging
• Accelerations, jerk and roll speed
• • Ride comfort evaluations

Other requirements

• Wheel/rail wear
• • Estimate travelled distance before reprofiling
  • May change the profiles into an unfavorable shape
• RCF Rolling Contact Fatigue
• • Initiates cracks in wheel and rail