PBL Lang Gar

Safety features of a car

Group member: Lu Zhen 14 Darrell Tan 04 Ong Yinn Jaye 17

Introduction

• The present cars are travelling in a much higher speed compared with the previous cars. As a result, it is much easier for the present cars to cause accidents.

• Therefore, by keeping testing, the design of the cars are changing and improving.

Crumple Zones

The crumple zone is a structural feature mainly of automobiles. Crumple zones have also been incorporated into railcars in recent years. They are designed to absorb the energy from the impact during an accident by controlled deformation – creating a smaller impulse.

Seat belts• A safety harness designed to secure the occupant of

a vehicle against harmful movement that may result from a collision or a sudden stop.

• As part of an overall automobile passive safety system,

seat belts are intended to reduce injuries by stopping the wearer from hitting hard interior elements of the vehicle, or other passengers (the so-called second impact), are in the correct position for the airbag to deploy and prevent the passenger from being thrown from the vehicle.

Seat belts• Example:

• If a car is travelling at 100km/h, the passengers inside are also moving at 100km/h. When a force is exerted on the car, the car stops, but not the passengers, according to Newton’s 1st law.

• Seat belts will help exert a force on the passengers, stopping and preventing them from getting hurt.

Airbags• Air bags are able to reduce the effect of the force

experienced by a person during an accident. They extend the time required to stop the momentum of the driver and passenger.

• During a collision, the motion of the passenger carries him towards the windshield. A large force needs to be exerted over a short period of time on the passenger to stop him.

• Instead of hitting the windshield, the passenger hits an air bag, thereby increasing the time of impact, which results in a decrease of force acting on the passenger.

Airbags

• An “Airbag control unit” monitors a number of sensors within the car. Upon heavy collision, the airbag control unit will trigger the burning of a gas generator propellant to rapidly inflate a nylon fabric bag.

• Nowadays there are multiple airbags in cars, used to protect the passenger’s knee, rear, torso etc.

Traction Control

• Traction control helps limit tyre slip in acceleration on slippery surfaces. Previously, limited-slip rear axles were used in many front- and rear-drive vehicles. However, the device cannot completely eliminate wheel slip. Hence, a more sophisticated system was needed.

Traction Control

• Traction-control systems use the same wheel-speed sensors employed by the antilock braking system. These sensors measure differences in rotational speed to determine if the wheels that are receiving power have lost traction.

• When the sensors determine that one wheel is spinning more quickly than the others, it automatically "pumps" the brake to that wheel to reduce its speed, thus lessening an individual wheel speed. However, some traction-control systems also reduce engine power to the slipping wheels

Head Injury Protection

• Head restraints are designed to restrict head movement during a rear-impact collision and reduce the chance of neck and shoulder injury.

• A properly configured head restraint system can reduce or even prevent such an injury.

All-Wheel Drive

• An All-wheel-drive vehicle has the ability to send power to all four wheels (not just the front two), giving the car more traction and stability. This helps when driving off road or on rough terrain.

Thank you!