At Monash Motorsport, we strive to continue to push the limits of what we and the car are capable of, so that concepts and designs are constantly evolving and improving. One of the most recent manifestations of this has been the development of a hydraulically actuated mode separated suspension system, affectionately dubbed ‘Hydro’. This is a one of a kind system in FSAE, with only one other team having attempted the idea before.
The aims of such a system, as suggested by the name, is to separate and isolate each mode of movement (roll, pitch, heave, bump and warp) so that they may be independently tuned for a fully optimised set up. Regular shocks and springs do not allow such separation – if the springs on a conventional damper are changed for roll, they may also change pitch, heave and warp stiffnesses even if these are not required to change. The challenge then was to design a system that achieved these aims.
The first Hydro system was designed by our 2013 Chief Engineer Andrew Trathen during 2014, designed to be compatible with our M14 car so it could be validated on track. Even though there were still many issues to fix with the initial iteration, the feedback from the drivers on its maiden run were very encouraging, with one describing the feeling as “like a hover-car”. This gave the team the confidence to move ahead with the concept and redesign it for 2015, with previous suspension leader Alan McNaughton leading the design.
As the new Hydro system was being designed alongside the rest of M15, instead of having to be retrofitted to an existing car, it allowed the team to develop a better optimised system. The final design isolated roll to be tuned through Hydro, with heave and pitch controlled by the use of monoshocks and (theoretically) completely eliminating warp stiffness. The configuration of the lines allows fluid to merely transfer between 4 actuators when the car is experiencing pitch, heave, bump or warp, but hydraulically compresses the springs in the accumulators during roll. By changing these accumulator springs and tuning the damping settings on the integrated damping unit, called the “snowflake”, we are able to tune roll independently of the other modes. Two monoshocks (front and rear), which are simply extended Ohlins dampers, provide heave and pitch stiffness which can be tuned by conventional means. As neither the Hydro system or monoshocks provide warp stiffness, the system has theoretically zero warp stiffness. This is highly advantageous as it allows maximum contact with the ground over bumps and road irregularities, allowing one wheel to experience the disturbance but which is not propagated to any other wheel, maximising the total grip available.
Due to the unique nature of the system, most of the components were designed and manufactured from scratch by our students, taking countless machining and assembly hours.
Hydro was put to the test at FSAE-A in December last year and was a resounding success, performing well on track and receiving praise from the design judges. However the system still has room for improvement, and this is what we have been working on this year in preparation for the upcoming Europe campaign. System components have been redesigned and manufactured to remove small leaks, and lines have been rerouted for both efficient layout and rule requirements. With the implementation of these changes, the performance of the system has noticeably improved and is sure to give us a competitive edge against the world’s top teams in Europe.
– Simone Briggs, Suspension