Study on car body frame manufacturing / Khamis Rezan Mahat, Ahmad Shuhaimi Jalaludin and Mohd Irwan Ali

At its simplest, a car is a beam support at each end by the wheels, so it has to be strong enough not to sag in the middle a property called beam stiffness. A car must also have torsion stiffness. The ability to resist the twisting stresses imposed by any irregular road surface. Structural strength is also necessary to cope with particular loads, such as the weight of the engine, thus of the spring and minor impacts. To have a strong structure without too much weight means using material as efficiently as possible. But strength is not everything, in addition to providing space for the occupants and their luggage, the body work must also protect them in an accident. A car body will absorb little of the impact energy in a collision, so more will be transmitted to the occupants. On the other hand, a body that is to weak might collapse on to them. For seat-belted occupants, the ideal is an impenetrable, rigid box, with weaker ends, that will absorb impact energy by progressive crumpling and stop the car less suddenly. The requirements of good performance will also affect the designers final decision on the shape of this car. The cars movement is opposed by the air. It is travelling through, as well as by the rolling resistance of the tyres. This air dray, as it is called, increases proportionately to the square of the speed for example, is speed is doubled, dray is quadrupled, if speed is trebled, drag is nine times as great.