The design of automotive suspension does not only aim at increasing dynamic performances, but also improving the handling of vehicles. Handling derives from the sensations transmitted by the vehicle to the user on the adherence conditions, in combination with the degree of sensitivity of the controls regarding the lateral response. Improved handling refines the driver’s attunement to the car, making the prediction of dynamic reactions easier and allowing for greater confidence in reaching the limit. This volume offers a detailed guide to understanding the functioning of suspensions and the related elastokinematic study. This focuses on controlling the lateral dynamic behavior of the vehicle, intended both as absolute performance and driving feeling.
The text has a scientific approach and requires an adequate technical background for a full understanding of the subject discussed. However, many of the topics covered are accompanied by practical considerations that do not require extensive mathematical knowledge. The illustrations are purposely very simple and schematic, because they are oriented more towards the learning of physical phenomena than the detailed representation of the elements involved.
The book is aimed mainly at:
· Undergraduates in mechanical engineering or young engineers who want to use it as an application support to the topics covered in the Vehicle Mechanics course;
· Junior race engineers;
· Students of technical institutes in the sector;
· Professionals in the automotive tuning sector;
· Automotive enthusiasts looking for a specific in-depth study;
· Readers who are passionate about dynamic model cars.
INDEX
foreword
CHAPTER 1. VEHICLE DYNAMICS – Maneuvers and goals
1.1. The vehicle from a dynamic point of view
1.2. What do we ask to the vehicle?
1.2.1. Straight line driving
1.2.2. Cornering
1.2.3. Slalom
1.3. What does the dynamics vehicle behavior depend upon?
Chapter 2. TIRE ROAD INTERACTION – Notes
2.1. The quadricycle
2.2. The slip angle
2.3. The brush model
2.4. Camber effects on the tire characteristic
2.5. Other effects on the tire characteristic
2.5.1. The coefficient of adherence
2.5.2. The temperature and the inflation pressure
2.5.3. The vertical load
2.6. The load transfer and the slip angle
2.7. Summary
CHAPTER 3. THE MOTIONS OF THE VEHICLE
3.1. General considerations
3.2. Sprung and unsprung masses
3.3. The pitch and rebound motions
3.4. The bump stiffness
3.5. The sizing of the springs
3.6. The roll and yaw motions
3.7. The roll stiffness
3.8. The sizing of anti-roll bar
3.9. The load transfer in stationary condition
3.10. The distribution of load transfers in stationary conditions
3.11. The roll angle
3.12. The sizing of the roll stiffness
3.13. The sizing of the shock absorbers
3.14. The dynamic influence of the shock absorbers
3.15. Summary
CHAPTER 4. LATERAL DYNAMICS – Use of analytical models
4.1. The analytical approach
4.2. The evaluation of the slip angles
4.3. The acceleration and the evaluation of center of gravity velocity
4.4. The single-track model
4.5. The sideslip angle gradient
4.6. The understeer gradient
4.7. No stationary conditions
4.8. Summary
CHAPTER 5. SUSPENSION – Architectures and schematizations
5.1. The schematic of the suspensions
5.1.1. The elastic bushings
5.2. Front suspensions
5.2.1. Double wishbone
5.2.2. McPherson
5.3. Rear suspensions
5.3.1. Twist beam axle
5.3.2. Rear Double wishbone and rear McPherson
5.3.3. Bilink
5.3.4. Multilink
5.3.5. Trailing arm and semi-trailing arm
CHAPTER 6. SUSPENSION – Set-up and operation
6.1. General description
6.2. The characteristic angles of the wheels and the geometric quantities of the suspension
6.3. The Camber
6.4. The Toe
6.5. The effect of the toe on the lateral characteristic of the tire
6.6. Toe variation under longitudinal load
6.7. The kinematics of the suspension
6.7.1. The roll center
6.7.2. Camber variation in bump travel
6.7.3. Camber variation when cornering
6.7.4. Alteration of the kinematics in the roll transient due to the shock absorbers
6.8. Longitudinal kinematics
6.8.1. Calculation of the ICSV position
CHAPTER 7. THE STEERING SYSTEM
7.1. The Caster
7.2. The Caster trail
7.3. The longitudinal arm at wheel center
7.4. The King Pin Inclination
7.5. The King Pin Offset
7.6. The scrub radius
7.7. The steering of the wheels
7.8. The steering mechanism
CHAPTER 8. VEHICLE DYNAMICS – Performance evaluation
8.1. The evaluation tools
8.2. Steering pad
8.2.1. The understeer curve
8.2.2. The sideslip angle
8.2.3. The roll gradient
8.3. The response of the vehicle in stationary
8.4. Step steer at constant speed
8.4.1. Yaw velocity and sideslip angle
8.4.2. Lateral acceleration and sideslip angle
8.4.3. The relaxation length
8.4.4. The roll angle
8.4.5. Considerations on different behaviors
8.5. Summary
CHAPTER 9. VEHICLE DYNAMICS – Achievement of the targets
9.1. Straight line driving
9.2. Cornering
9.3. Slalom
Analytical index
List of main symbols and abbreviations
Bibliography
