Design of various vehicle safety components - Research Paper Example

Your Full Vehicle Safety Components Serving to Create Inelastic Collisions Inelastic Collisions are the collisions where kinetic energy is not conserved. The energy is turned into vibrations, dissipated as heat and/or absorbed by components leading to their deformation. There are several components in the vehicle that are designed to, during impact, absorb energy and/or get deformed thereby reducing the impact energy transferred into the passenger cabin, hence on to the passengers. This paper is a brief discussion of design of some of these components and how they serve to create inelastic collisions. 1. Bumper Bumpers are the front-most and the rear-most parts of a vehicle.

In most collisions, bumpers are the first point of contact for a vehicle. The bumper generally consists of a plastic cover over a reinforcement bar made of steel, aluminum, fiberglass or plastic. The bumper bar and its attachment are designed to crush in a low-speed crash to absorb energy. In some cases, polypropylene foam or formed thermoplastic is used in addition to or instead of crushable brackets and a bar. This allows for even more absorption of energy. By absorbing energy and getting crushed, the bumper creates inelastic collision by reducing the transfer of kinetic energy.

The recent trend in bumper design, however, is related more to the pedestrian safety. 2. Crumple zones in cars Crumple zones are parts of the car that are designed to deform and crumple during collisions, thereby absorbing energy. These parts are typically in the front part of the vehicle, although they may also be in other parts of the vehicle. Crumple zones accomplish two safety goals: they reduce the initial force of crash and they redistribute the force before it reaches the passenger cabin.

Crumple zones reduce the initial force of impact by creating a buffer perimeter around the most rigid parts of the car (engine and cabin). By surrounding these rigid parts, crumple zones start the vehicle deceleration thereby absorbing kinetic energy. Auto makers do not divulge the specifics of crumple zone designs but simple designs can include frame segments built to crush under impact. More advanced design includes materials engineered to absorb kinetic energy like honeycomb design which is stiff under normal circumstances but can crumple in a crash. 3. Seatbelts During an impact with a steady object like a tree, generally, the vehicle comes to a stop in a very small distance (1 foot) due to damage taken by crumple zones.

If the passenger had no seatbelt, due to the momentum, s/he would be thrown forward and even out through the windscreen. The job of seatbelt is to reduce this distance that the passenger would normally travel if they were without seatbelt at the time of impact. The seatbelt serves to create inelastic collision by reducing this distance and by absorbing the kinetic energy of passengers itself. Recent design improvements have been to make the seatbelt slightly stretchable. More kinetic energy is then absorbed by the seatbelt and is used in seatbelt getting stretched. 4. Headrest The headrest comes into play as a safety component mainly during rear end collision of a vehicle.

When the vehicle is hit from the back, the upper body of the passenger would also tend to go back, the head more so. As the head goes back, it makes contact with the headrest on the way. The headrest absorbs the kinetic energy of the head thereby creating inelastic collision. If the head of the passenger was resting on the headrest before the impact, nearly all kinetic energy of the head going back would be absorbed by the headrest. The headrest material (generally foam) absorbs energy by getting “deformed”. 5. Collapsible Steering Column At the time of impact, the driver tends to fall towards the steering wheel.

If the steering wheel is completely rigid, it could damage the driver’s ribs to say the least. However, cars now come with a collapsible steering column (CSC) which is designed to collapse on application of a threshold pressure. The steering column is a long shaft that connects the steering wheel and the steering gear box. In a CSC, this arrangement is made with an inner and outer sleeve (like a telescope) pressed tightly together with a number of ball bearing in between. These ball bearings sit in sleeves which are held together with a strong safety resin.

This resin is designed to shatter when there is sufficient pressure applied. So, when the driver moves forward towards the steering wheel, the CSC absorbs the kinetic energy and collapses. Thus it makes it an inelastic collision. 6. Air bags Air bags act as cushion between the passengers and the vehicle body during collision. The air bags are designed to be inflated on impact. A central airbag control unit controls their deployment. When the trigger to deploy is reached, a gas generator propellant rapidly inflates a nylon bag.

When the passenger comes in contact with the bag, the bag gets squeezed and the gas escapes from small vent holes in the bag. The air bag thus absorbs the kinetic energy of the passenger thereby creating an inelastic collision. 7. Side door beams The side door beam protects the occupants from side impact. The beam is added as reinforcement on the side doors. During a side impact, the beam gets deformed by absorbing kinetic energy of the collision. Depending on weight considerations for the designer, the side door beam may be made of steel, corrugated aluminum or even fiberglass now days.

References Automotive Coalition for Traffic Safety. What you need to know about Airbags. November 2002. http://www.nhtsa.gov/people/injury/airbags/airbags03/images/Air%20Bags0307.pdf Lee K. Joo W. Song S.Cha I. Park G. Optimization of an automotive side door beam, considering static requirement. D07502 IMechE 2004. Proc. Instn Mech. Engrs Vol. 218 Part D: J. Automobile Engineering. P51 Nave R. Web. 19 May 2011. http://hyperphysics.phy-astr.gsu.edu/hbase/seatb.html#cc1 Park, K. Han M. 2000. Intelligent headrest design for rear impact safety and driver’s convenience.

Seoul 2000 FISITA World Automotive Congress. Schuster P. California Polytechnic State University. 2006. Current trends in Bumper design for Pedestrian impact. Paper Number 2006-01-0464.