Everything you always wanted to know about vehicles but were afraid to ask
MODERN car design has been transformed by the use of computers. The effect of this can be seen not only in how a car looks but also in how it performs in a crash and its ride and handling. The process designers now use to ensure that a car performs to its optimum is called finite element analysis (FEA). Twenty years ago a new car started life as sketches on paper from which scale models and then fullsize mock-ups were created using clay and other materials. Today the sketches are done on-screen and the models created by computer-controlled machines that carve the required shapes from polystyrene or clay. However, the real advantage of using computers is that they enable designers to work out accurately how components and materials will react when the car is driven. How a car responds used to be worked out using a mix of intuition, mathematics and repeated testing. Today the use of FEA means that the precise behaviour of every nut, bolt and piece of metal can be calculated exactly before it is even made. The principle is simple. Although designers cannot predict how complex shapes behave when subjected to different forces or temperature changes, they do know exactly what simple ones will do. Using FEA, complicated car components are divided into tiny squares on screen this looks as though a net has been stretched over the car. Then a theoretical force is applied at a given point and its effect on the squares it touches is calculated. This process continues through the structure of the car. None of the calculations is especially difficult, but the sheer number of them had previously been beyond designers. Today computer-aided design is so accurate that components such as engine blocks have variable wall thicknesses to ensure the stresses in them are perfectly even, and a car can be crashed countless times to assess its strengths without it ever having been built.