# PPT_Chapter_9

#### Slide_1: Vehicle Dynamics

* Vehicle Dynamics is a study of how a vehicle will respond to various situations.
* It plays an important role in the development of the vehicle.
* Understanding Vehicle Dynamics is required for predicting the behaviour of any vehicle under different conditions.

#### Slide_2: Acceleration
* Acceleration is defined as the rate of change of velocity with respect to time.
* Acceleration formula is given as:

#### Slide_3: Types of Acceleration

* Uniform and Non Uniform Acceleration

#### Slide_4:Types of Acceleration(Cont)
* Velocity Time Graph


* Average acceleration:The slope of the line between the time interval t1 and t2 gives the average value for the rate of change of velocity for the object during the time t1 and t2.
* Instantaneous acceleration:It is given by the slope of the tangent on the v-t curve at any instant.

#### Slide_5: Braking

* Braking is an application of frictional force to reduce the speed of the moving object and bring it to halt.
* In pure rolling motion, friction is required to start, stop, and change the motion of a wheel.
* Braking force (F) may develop between the tire and the road surface as shown

#### Slide_6:Braking Force and Braking Torque
* Braking force mainly depends on the coefficient of friction between the tire and the ground and 38 normal reactions on the wheel.
* Free body diagram of the wheel,

#### Slide_7:Method to control wheel locking
1. Anti-Lock Breaking System
An anti lock braking system (ABS) is a safety system on motor vehicles which prevents the wheels from locking while braking.

Ref: https://tse1.mm.bing.net/th?id=OIP.zN3E-36P58Mnih7rIQwFTQHpi&P=0&w=258&h=172

#### Slide_7:Method to control wheel locking(Cont)
2. Electronic Brake Force Distribution (EBD):
EBD controls rear-wheel braking based on detection of loss of traction at the front and the rear wheels when the brakes are applied.
Ref: https://tse4.mm.bing.net/th?id=OIP.FMpxOFo-ECEHg1X2y87wHAHaE8&pid=A

#### Slide_ :Suspension System

#### Slide_: Steering System

* The car steering system is the most important part in automobile vehicle steering control.
* For effective control of the vehicle throughout its speed range with safety proper steering is necessary.
* Automobiles are always equipped with front-wheel steering.

#### Slide_ :Function of Steering System
* With the help of the steering system, the driver can control the vehicle.
* The steering provides stability to the vehicle on the road.
* It minimizes tyre wear and tear.
* It prevents road shocks from reaching to the driver.
* The steering provides self-rightening effect after taking a turn.

#### Slide_9: Types of The Steering System in an Automobile
1. Bicycle Steering

#### Slide_10:Types of The Steering System in an Automobile(Cont)
2. Turntable or Centre Pivot Steering

#### Slide_11: Types of The Steering System in an Automobile
3. Ackerman Steering or Side Pivot Steering

#### Slide_ :Types of steering system depending upon the leverage

There are three types of steerings depending upon the leverage provided between the road wheel and the steering wheel and also the number of shocks and vibrations transmitted from the road wheels to the steering wheels
1. Reversible Steering
Reversible steering is one in which the gear ratio is 1:1.
2. Irreversible Steering
Here gear reduction between and wheels and the steering wheel is very high.

#### Slide_: Steering Gears
* It is a device for converting the rotary motion of the steering wheel into the straight-line motion of the linkage with a mechanical advantage.
* The steering gears are enclosed in a box called the steering gearbox.

#### Slide_ :Roll Over Control
* A rollover is defined as any vehicle rotation of 90° or more about any true longitudinal or lateral axis.
* Rollover occurring conditions
• Traveling at high speed on curved road.
• Sever cornering maneuver.
• Traveling on collapsing road and suddenly providing steering input for a vehicle with a low level of roll stability.
• Losing control due to a rapid decrease of friction, such as driving on icy road.
• Laterally sliding of the road.
• Sliding from a cliff.

#### Slide_ : Effect of Speed and Centrifugal Force

• If you double your speed, the overturning force will be four times higher. As the speed increases the trailer tracks wider and forces increase on rear axle.
• It increases by squaring so that 10% increase in speed causes 100% increase in force.
Double the speed is four times the force.

Ref: https://tse4.mm.bing.net/th?id=OIP.ZdItlTq9JsTZOa1WDqgHaFV&pid=Api&P=0&w=237&h=172

#### Slide_ : Working of Rollover control system
* Roll Stability Control
* RSC works with the help of a gyro sensor and Electronic Stability Program (ESP/ESC) of the vehicle.
* 
Ref: https://tse2.mm.bing.net/th?id=OIP.XUZ2LKqXpFuxggHaFi&pid=Api&P=0&w=215&h=161

#### Slide_ :Tyres and Tyre Dynamics
* Tyres are the main contact your vehicle has with the road.
* Tyre Dynamics
1. Slip Angle
2. Cornering Stiffness
3. Slip Ratio
4. Friction Circle

#### Slide_ :Ride Comfort

* Ride comfort control systems improve vehicle comfort and increase driving pleasure.
* Ride comfort starts with understanding the basics of suspension, in specific the 2 main components:

1. springs
They are the most easily identifiable piece of a car’s suspension visually and are the main controlling component in whether or not a vehicle rides ‘hard’ or ‘soft’.

source: https://tse4.mm.bing.net/th?id=OIP.k8g9mQHaHa&pid=Api&P=0&w=300&h=300

#### Slide_ :Ride Comfort(Cont)
2. Dampers
They are common shock absorbers, otherwise known as ‘dampers’ and more commonly known to the layman as shock absorbers.

source: https://tse3.mm.bing.net/th?id=OIP.kvzMnIzYcEjSc7oN1FTx0QHaLc&pid

#### Slide_ :Dynamic Axle Loads

* A load, when applied to an object, subjects it to some force.
* The axial load ‘f’, which is along the axis of rotation of the object, and passing through the centroid, is due to the mass ‘m’ of the load on top.

source: https://tse4.mm.bing.net/th?id=OIP.aH5tepMpgh_u559DUsQ6fwHaEK&pid=Api&P=0&w=272&h=154

* Axial Load Calculation
The formula to calculate the stress due to axial load is,
σ = F/A

#### Slide_ : Free Body of Vehicle
* A free body diagram is defined as an illustration that depicts all the forces acting on a body, along with vectors that are applied on it.
* The three main aspects that need to be considered in drawing these diagrams are:
1. The direction of the force
2. The magnitude of the force
3. The Origin/Source/Application point of the force.

#### Slide_ : Free Body of Vehicle(Cont)
* Free body diagrams are always represented in the form of two-dimensional figures, which consist of the ‘X’ and ‘Y’ axis.
* Types of Forces
1. Applied Force
2. Normal Force
3. Gravitational Force
4. Frictional Force
5. Tensional Force

#### Slide_ : Free Body of Vehicle(Cont)
Air Resistance/Drag
* An object is in motion in the air, it shows the presence of air resistance, which acts in the opposite direction as that of the applied force.
* This vector is also called drag, which can act on the back-end of the body in motion.

Ref: https://tse1.mm.bing.net/th?id=OIP.hLsB5Idy3u5FJBDzs

#### Slide_ : Free Body of Vehicle(Cont)

* The diagram aboveshows the same box, but on an inclined surface.
* The force of gravity will be acting in multiple direction that is at an angle to the surface as well as perpendicular to the surface.
Ref: https://tse2.mm.bing.net/th?id=OIP.LX2v5Jxzf_vvnvwlMEwU2wHa