Chassis Design and Manufacture
This month has been chassis month at UBR. The jig is fully designed and being manufactured and the tubing all cut to size thanks to Duright Engineering Ltd. for their help and support. Now when term finishes we can start to manufacture our car and begin to make headway into the project. As part of this some of the new members to the team have been looking into the design of a chassis and the differing ways that this is done, below is an article written by one of the first year Mechanical Engineers.
Alternative Chassis Designs
UBRacing have always used a steel tube frame chassis as this is the most straightforward option, but it is by no means the only option that is open to us. One of the main alternative options in chassis design that UBR are considering is a monocoque chassis. A monocoque chassis is one where the external surface of the car takes the majority, if not all, of the stresses that are put on the car.
The main advantages of this approach is the increase in strength and stiffness of the chassis with decreased weight which is everything a formula student car could ask for. Increased strength of the chassis leads to better transfer of power throughout the body of the car to the wheels, whilst less weight is always desirable in formula student cars since a good power-to-weight ratio is key to success.
Some complications arise with manufacturing of a monocoque chassis since ideally the chassis would all be one part which is relatively hard to make without professional aid, especially when compared to the classic steel tube chassis. Another complication is in the modelling and calculations involved in the design of the chassis. Steel tubes are very simple in terms of strength properties and therefore you can calculate the stresses they can take very easily, but monocoque chassis are more complicated in their attributes.
Finite Element Analysis (FEA) is used extensively in chassis design and is extremely important in monocoque chassis to calculate stress and resonant displacement at points in both types of chassis to ensure a safe and strong chassis for the UBR car. Another consideration is the fact that the car’s electronics are grounded through the steel tube frame which might not be possible in a monocoque chassis.