Automotive Chassis Design & Nvh Performance

A chassis is the supporting frame of a car. It gives the car strength and rigidity, and helps increase the car's crash-resistance through energy absorption. If a car were a human body, the chassis would be the skeleton. During a fall, a person with strong bones is likely to be hurt less than someone with weak bones. The same goes for a car in an accident. The chassis helps keep a vehicle rigid. A strong chassis will keep the back end of a car from falling out of alignment with the front end, while remaining as stiff and unbending as possible.

The chassis is especially important in ensuring low levels of noise, vibration and harshness (NVH) throughout the vehicle. Not only does a reduction in NVH allow for a more pleasant driving experience, but by putting less stress on connecting components it can help increase the life span of these components. The key determinant permitting reduced levels of NVH is energy absorption. By having a high level of energy absorption, NVH levels are lowered, but more importantly, passenger protection can be enhanced in the event of a collision.

Plastic is making an inroad into the chassis market. Innovations in plastic technology have brought about the development of successful chassis applications that would not be possible using any other family of materials.

The world's second all-plastic vehicle, the Baja, has a plastic composite chassis. The vehicle is ideal for off-road tropical environments where its composite body and chassis resist sand and seawater. Its combined thermoplastic and thermoset skin and frame take advantage of plastic's strength to manage energy, enabling it to pass both the United States' and the more stringent European computerized crash tests. The chassis' light weight is a tremendous advantage to manufacturers, since weight savings makes parts easier to transport. It also provides consumers better fuel economy, and with the fuel savings that light weight brings, helps preserve resources and protect the environment for us and our children.

Since plastic and plastic composites have only recently been considered for use in frames, there is not yet a track record as to what types may be best suited to these applications. Experiments with plastic in frames may lead to future innovations enabling plastic to replace metal on a broader scale.

Crash-absorbing foam is a well-tested application. Door panels are filled with rigid, energy-absorbing polystyrene or urethane-based foam that acts as side impact absorbers, and help maintain a car's structural rigidity. These lightweight foams provide excellent energy management capability during a crash.

A drive shaft helps transmit power from the engine of a car to an axle. Thanks to plastic's excellent energy-management characteristics, a single-piece plastic-based drive shaft can help reduce levels of NVH. Since a drive shaft

...