Formula One side impact structures
For many years the regulations governing Formula One car construction have paid great attention to reducing the loads experienced by drivers during front and rear impacts. However, despite having to undergo side intrusion tests, it is only relatively recently that concerted efforts have been made to mitigate the loads exerted during a side impact. To this end, 2014 saw the introduction of new side impact structures on cars, designed to absorb energy in the event of such an impact.
The catalyst for this move was a crash experienced by driver Robert Kubica at the 2007 Canadian GP, where the side of the car impacted a solid object at an acute angle. At the time of this crash, the side impact structures used consisted of straight carbon fibre tubes that extended out from the car at a 90º angle. Kubica’s crash showed that, while these existing structures were very effective at absorbing crash energy in a direct side impact, if struck at an angle the tubes were prone to break away, negating their effectiveness.
FIA Institute research consultant Andy Mellor, who led the project to develop a new structure, explained in 2013, “We went back to basics to examine what a side impact structure really needs to do in different types of accident. We used Robert Kubica’s crash in Montreal as a specific reference point since that was a major impact at an acute angle.”
To find a more effective solution, the FIA approached teams and asked them to come up with a new design that was effective regardless of the direction of impact. Three teams came up with designs, which included both improvements to the existing tube-based system and other solutions such as a layer of aluminium honeycomb material bonded to the outside of the monocoque. However, as can be seen in the video below, the honeycomb approach was unsatisfactory, with the material breaking away under certain loadings.
Ultimately, a solution devised by Red Bull Racing was settled on, and this consists of a series of laminated carbon fibre pillars, constructed in such a way as to crush during an impact rather than break off. These pillars essentially disintegrate under impact, in much the same way as a front or rear crash structure, absorbing the energy that would otherwise be transmitted directly into the monocoque.
Unlike the previous crash structures, which were built individually by the teams and had to undergo separate crash tests, the new side impact devices are a spec item. Exactly where they are mounted is still left up to teams, as each monocoque is unique, but the mounting points must be able to withstand horizontal loads of up to 60 kN as well as vertical loads of 35 kN without deforming.
Although the new structures provide a higher degree of safety for the drivers, they also present more headaches for teams’ engineers, as Eric Gandelin, chief designer for the Sauber F1 team, explained before the start of the 2014 season. “The new changes now regulate the design of the structures. This means the dimension of the tube and the laminate is now set and the same for all teams. And these tubes are overall much bigger and result in bulkier sidepods, especially compared to the very slim sidepods we had on the C32.”
Written by Lawrence Butcher