Can I Use Lagrangian Equations to Calculate a Car's Response on an Uneven Road?

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SUMMARY

This discussion focuses on calculating a car's response while driving at 30 mph over an uneven road with bumps of height 0.05 meters and a length of 20 meters. The user, Alex, is considering using Lagrangian equations of motion to derive the system's response but is uncertain about the next steps. The conversation also touches on the concept of a "7DOF Car," which includes degrees of freedom for front and rear suspension, engine, passengers, and luggage. The calculation will likely involve formulating an ordinary differential equation (ODE) with a forcing component or deriving a transfer function based on displacement.

PREREQUISITES
  • Understanding of Lagrangian mechanics and equations of motion
  • Familiarity with ordinary differential equations (ODEs)
  • Knowledge of vehicle dynamics and degrees of freedom (DOF)
  • Experience with stiffness and mass matrices in mechanical systems
NEXT STEPS
  • Research how to formulate Lagrangian equations for multi-degree-of-freedom systems
  • Learn about calculating ordinary differential equations (ODEs) with forcing components
  • Study vehicle dynamics, particularly the impact of suspension systems on ride quality
  • Explore transfer functions and their application in analyzing mechanical systems
USEFUL FOR

Mechanical engineers, automotive engineers, and researchers in vehicle dynamics who are interested in analyzing car responses to uneven road surfaces using advanced mathematical techniques.

alexisonsmith
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So I am trying to calculate the system responsee if a car is driving 30mph over an uneven road with a bumpb of height 0.05 and a length of 20m between each bump. I have the stiffness matrix, mass matrix etc. However I am unclear about the next step, I think possibly by using the Lagrangien equations of motion but I am not sure

Thanks,

Alex
 
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you'll likely calculate an ODE with a forcing component... or the transfer function using displacement at two points (more likely).
But the reason I came to read this is really the "7DOF Car" part... How can you have 7 degrees of freedom? Do you have a DeLorean with a Flux Compensator :)? If it is a "car", I can really only see 2 DOF...
Please explain...
 
The reason is that you take into account the front and read suspension that is 4, after that the engine, 2 passengers on seats and some luggage in the back, at the moments I have the motion of x (in the vertical condition) and the motion around theta...
 

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