The course deals with the main relevant aspects of vehicle dynamics both on road and on railway; more in detail it present the basic topics to understand and to implement the behavior of:
- contact forces generation between road-tire and between track and wheel
- longitudinal dynamics (e.g. vehicle performances, max sped, max acceleration.; braking performance)
- lateral dynamics (e.g. oversteering and understeering; running stability )
- vertical dynamic (e.g. comfort; running safety)
inamica del Veicolo (M. Guiggiani)
Meccanica dell'autoveicolo (G. Genta)
Tire and Vehicle Dynamics (H.B. Pacejka)
Lezioni di meccanica del veicolo (A. Rindi)
Learning Objectives
The course aims to provide a basic knowledge about the dynamics of rail and road vehicles ;
in particular, the course aims to provide the fundamentals for understanding and modeling of the main aspects:
-contact road wheel and wheel-track
- Longitudinal Dynamics
- Lateral Dynamics
- Vertical Dynamics
Prerequisites
basic knowledge of applied mechanics
Teaching Methods
Frontal lessons
Further information
oral examination with tree different questions
Type of Assessment
Oral examination (normally three questions).
Course program
Road autovehicle
1. Tire-road Contact
Model of Coulomb
Brush model for longitudinal and lateral forces
Magic formulae; longitudinal, lateral and combined forces;
Influence on Adhesion curves of the vertical load, camber angle, speed...
2. Aerodynamic actions
3. Dynamics Longitudinal
Braking: Transfer load. Proportioning Braking System assisted braking systems (ABS, ESP ....)
Power curves, torque and specific consumption of an motor
Model 1 DOF model with Tire-road Coulomb model
Model 3-DOF model with Tire-road Pacejka model.
Vehicle Performance: Maximum gradeability, maximum speed on a level road, full throttle on a level road.
Choice of gear ratios
4. Lateral Dynamic
steering kinematics
Steering dynamic model 3 DOF; General equations of motion,
Directional stability: the linearized equations of motion; derived stability;
steering response; response to forces and moments.
5.Vertical Dynamics
Types of suspension
Comfort: 1 DOF and 2 DOF (quarter-model) models
Influence of the suspended masses
Rail vehicle
wheel-rail contact
Parameters that affect the coefficient of adhesion
Normal problem (Hertz theory)
Tangential Problem (linear theory of Kalker, theory of Johnson-Vermeulen, heuristic theories)
Track forces. Safety against derailment: wheel flange climbing, vehicle turnover, rail turnover. Wheel and rail wear. Ride comfort. Vehicle gauging.