In the beginning of car building, a simple body on a separate ladder chassis was all the rage. It is a cheap, simple and tough setup. Because of it’s strength and durability, it is still used in a lot of heavy off-road vehicles and things like large trucks.
The downsides of a separate ladder chassis are heavy weight and a lack of torsional rigidity. They’re heavy and they’re prone to twisting while driving.
The next stage of car chassis history was the common usage of monocoque construction. Most cars these days are made in a single, unitary piece, with the entire bodyshell being used to bear the load of the car.
It’s a cheap way of constructing a car, just like the ladder chassis setup. However, it’s much lighter and more rigid per kilo. Manufacturing-wise, a monocoque is an easy fit with the sheet metal used to construct today’s cars as well.
It is from the adoption of the monocoque, that crumple zones became a talking point for safety, because a monocoque car will crumple more easily than a ladder-chassis setup. So manufacturers started to design ways to control where and how this crumpling occurs.
Today, cars are getting heavier and heavier thanks to safety regulations, and customer expectations of what is included in their vehicle.
In an effort to combat this weight gain, many manufacturers (particularly high end sports car and supercar makers), are using such materials as thin aluminum, fiberglass, Kevlar and carbonfibre.
These materials are not well suited to the traditional way of producing a monocoque chassis as they are not as good at load-bearing.
The answer has been the modern interpretation of an old idea that pre-dates both ladder and monocoque car setups : The Spaceframe.
Put simply, a Spaceframe is a series of planks, bars or tubes arranged in geometric patterns (usually triangles) in a way that bears load well. (Think the trusses in a roof or the pieces that make up scaffolding).
Because of the amount of “bare-air” between the tubing, you end up with a super light structure. Because of the geometry involved, you also get something incredibly strong to bear weight and the multiple joining points mean huge amounts of torsional rigidity.
You can also create the Spaceframe in separate pieces to come up with intricate shapes to suit the aspirations of your car and include mounting points for vital components.
Then you can create sub-frames for the gearbox, differentials, etc and hang the entire driveline off the Spaceframe. You can also stick body panels to it made out of all the aforementioned lighter materials, because the Spaceframe itself bears all of the load.
Downsides to the Spaceframe approach? There’s really only one – it’s more expensive.
Due to the labour intensity of both designing and hand-melding multiple tube components together, a Spaceframe costs more than an ordinary monocoque car to build.
The price is a worthwhile compromise for cars like the Audi R8 to remain as light, stiff and efficient as they can be.
Michael Adams
Article Originally Created for World Car Reviews