Safety

Now no racer would ever imagine that they're going to have a really BIG accident, and certainly one where they impact the rollbar at a really nasty angle. I spent the thick end of a decade investigating RTAs and I've seen the impossible happen quite a lot. So, I wanted to see what my allegedly natty rollbar design really would do in the event of a shunt. I've loaded the top part of the rollbar with 10kN (effectively a tonne) and at the same time applied the same level of force horizontally - sort of landing upside-down while sliding into a brickwall with just the rollbar taking the loading. This is nowhere near as sever as F1 for example, which expects loading of 90kN through the rollover structure.

With this loading the rollbar only just survives - the factor of safety, i.e. the ratio between yield stress and max stress, is 0.97 so some parts of the rollbar would just start to bend. Dynamic crush testing is way beyond my knowledge of Cosmos, but I'm more certain than ever that I'll want either front stays on that roll bar or a full roll cage tying the rollbar to another roll hoop around the steering wheel area. Once I've got the rest of the chassis, I'll repeat the analysis and see what the whole car will do. I'll also see if I can get some dynamic analysis done using Cosmos.

The other thing I want to do is have sensible impact protection to the front and sides. Aluminium honeycomb is your friend here and I've got both Hexcel's design document and the F1 regulations as an input value:

"For the purposes of this test, the total weight of the trolley and test structure shall be 780kg and the velocity of impact 15.0 metres/sec.The resistance of the test structure must be such that during theimpact:
- the peak deceleration over the first 150mm of deformation does not exceed 10g;
- the peak deceleration over the first 60kJ energy absorption does not exceed 20g ;
- the average deceleration of the trolley does not exceed 40g ;
- the peak deceleration in the chest of the dummy does not exceed 60g for more than a cumulative 3ms, this being the resultant of data from three axes.
Furthermore, there must be no damage to the survival cell or to the mountings of the safety belts or fire extinguishers."

There's similar for side impact as well. I'll see what sort of volume of expanded honeycomb is required and see where it can be fitted in. I've seen some nasty intrusions into spaceframe chassis over the years and it's a risk I'd like to design out as much as possible.