VEHICLE DYNAMICS FUNDAMENTALS

Dr. T.M Cameron/Kettering University

Dr. T. Shim/University of Michigan, Dearborn

I           Introduction

a. Ride & Handling terminology

b. Coordinate Systems (inertial vs. body-fixed)

c. Rigid body dynamics

d. Simple example: dynamics & stability of a shopping cart

II. Road Loads

a. Aerodynamic lift and drag, afterbody drag, forebody effects, underbody drag

b. Internal friction, rolling resistance

III. Tire Mechanics

a. Tire-road interaction

b. Lateral forces; effect of normal forces

c. Longitudinal forces

d. Combined lateral and longitudinal forces

IV. Acceleration Performance

a. Acceleration performance

i. Tractive effort

ii. Effective inertia, effect of gear ratio

b. Gradeability performance

i. Power-limited gradeability

ii. Traction-limited gradeability

c. Fore-aft load transfer (front to rear “squat”)

V. Braking Performance

a. Braking torque, effective inertia

b. Traction limits, road adhesion

c. Fore-aft load transfer (rear to front “dive”)

d. Braking efficiency, stopping distance, optimal braking

e. Effects of tire lockup

VI. Ride Dynamics

a. Bounce & Pitch

b. Road excitation

c. Suspension, sprung & unsprung mass

d. Vertical ride response, quarter vehicle model

e. Pitch ride response, half vehicle model

f. Active control systems for vehicle ride

g. Flexible body frequencies

VII. Steady-state Cornering

a. Roll & Yaw

b. Ackerman Geometry

c. Understeer/oversteer

d. Yaw rate and lateral acceleration gains

e. Bundorf Cornering Compliance

f. Understeer gradient

g. Roll moment distribution

h. Camber/roll steer

i. Nonlinear vehicle suspension

j. Anti-dive, anti-squat

k. Vehicle rollover & roll center

VIII. Trailer Stability

a. Lagrange equations, body-fixed coordinate systems

b. 1-DOF and 2-DOF trailer models

c. Lateral stability and critical speed

IX. Software tools

a. CarSim, TruckSim

b. ArcSim Vehicle Dynamics Simulator (U.S. Army TARDEC; UMich ARC)

c. Static Roll Threshold Calculator (New Zealand Land Transport Safety Authority)