Name: Miguel Cuni Municio
Sub-team: Chassis & Dynamics
Part: Suspension System
Purpose of the part? The suspension’s job is ultimately to maximise the tyre contact patch at all times. Every other single purpose of the suspension system comes under this primary aim. The kinematics and dynamics of the suspension have to be designed and tuned in track to optimise grip levels and control tyre degradation. In addition stiffness is paramount for the suspension to work as intended with minimum compliance.
What are the specific features? The entire geometry had to be redesigned for the new 10” rims the team purchased this year. Not only that, the rear geometry has been optimised to remove the rear section of the chassis, bringing the rear bulkhead ahead of the rear axle, whilst improving the overall kinematics of the vehicle.
In addition, the vehicle size has been heavily reduced, there has been a 50mm cut in wheelbase and 50mm cut in both front and rear tracks. This change, alongside the great effort in weight reduction by the rest of the team, will contribute in further reducing the moment of inertia of the vehicle, making UGR-19 much more responsive than any of the cars that have been built in the past.
Further, the steering geometry has been thoroughly revised. There is a change from front steer to rear steer in order to increase Ackermann levels, reduce understeer and increase vehicle responsiveness.
One of the main focus for UGR-19 is weight saving, for that reason great effort has been taken in reducing mass within the suspension mechanism. Length of control arms has been reduced in order to save weight, also threaded inserts have a reduced size to further weight savings.
What testing has been carried out? At the moment we are testing the entire vehicle making sure everything works as intended. Therefore, we are elaborating a baseline set up our drivers feel comfortable driving with, so that we can compare test data with simulations, validate the design and develop a vehicle set up that will give us an advantage over our competitors!
What were the challenges to overcome? Designing a suspension system is a challenge in itself. There is an infinite number of methods and options and we need to choose only one. The greatest difficulty is devising a geometry that shapes the chassis in a way it perfectly blends the rest of the components and driver in one single package. Therefore, before placing a single points everything else has to be put together in order to achieve a truly synergetic design, creating harmony between subsystems in the car.
In addition to that, because of the smaller rims and overall smaller package fitting the control arms while improving the vehicle kinematics has been a rather difficult task. Countless hours have been spent simulation various set ups until the final iteration was achieved. Particularly troublesome has been the steering geometry. Due to the increase in Ackermann levels further clearance was required, making the front geometry of the vehicle pretty complex to design.
What are the improvements over last year? Due to the revised geometry and effort by the rest of the team to place every component as low as possible, the CoG has been reduced a 3%, which with revised suspension geometry helps reduce body roll by 4.5%.
In addition, there has been a 30% weight reduction in suspension mechanism mass thanks to the lower length of the suspension arms and smaller threaded inserts. Another reason to reduce the length of the control arms is to reduce compliance. For the same stress, a smaller link is going to experience a lower deflection since the strain is defined by displacement over original length.