MATERIAL selections have been the primary exercise in the design and development of automotive vehicles since the early days of mass production.
The general trend showed that the material development and innovations were focused on weight reduction of the vehicles with the introduction of materials which were inexpensive and yet superior in mechanical properties.
Car users are more familiar with the functionality of their vehicles such as the engine, transmission and ABS system, but little thought is given to the raw materials that are used in the production of the vehicles.
Automotive manufacturers use a tremendous number of materials in the mass production of their vehicles.
The types of materials vary from the smallest parts such as screws and clips to the larger components such as engine and transmission. Five major materials are predominant in the development of a vehicle and their utilisation has significant impact on the weight and cost of the vehicle produced.
Steel was largely used by automobiles of the late 1980s for the body and frame, to produce vehicles that were strong but heavy. The vehicles compromised on fuel consumption as they had lesser value compared with the vehicles today.
Percentage composition by weight of the major materials include high strength steel about six per cent, other steel 50 per cent, iron 15 per cent, plastics seven per cent, aluminium four per cent and others (such as rubber, glass, textile) about 18 per cent.
Aluminium began to replace steel and iron components in the mid 1990s, thereby reducing the weight of the vehicle, leading to significant improvement in the performance.
Composition of major materials during this period was altered as following: high strength steel 10 per cent, other steel 43 per cent, iron 12 per cent, plastics seven per cent, aluminium eight per cent and others about 20 per cent.
Attempt to reduce the weight and cost of modern cars in the late 2000 had led to the use of more plastic materials and reduction in iron-made components. The composition of major materials was then: high strength steel 13 per cent, other steel 42 per cent, iron seven per cent, plastics nine per cent, aluminium eight per cent and others 21 per cent.
The weight of a modern vehicle is centred on the body, including frame and panels that are attached to it. According to current estimation, the body constitutes 40 per cent of the vehicle weight.
Interior components contribute some 15 per cent, while chassis and powertrain make up 24 per cent and 16 per cent of the vehicle weight, respectively.
However, the percentage may differ in vehicles that use sub-frames for front-wheel drive instead of chassis, which is more common for rear-wheel drive. Electrical systems are more in use in modern vehicles as technology advances further, contributing to five per cent of the vehicle weight.
It is apparent that for further weight reduction exercises, more focus should be given to body design and construction using lighter materials than high strength steel. Composite material is becoming the best available choice for vehicle body. Metal and ceramic composites may offer alternatives in replacing some of the iron and other steel parts.