deceleration peak of ia data

[Dharma]

I have done two kinds of simulation, one is quasi static and one dynamic. in the second one I have good deceleration data, but in the quasi static simulation I have a big peak of deceleration. I've red in the rules that we can use a filter...but in your opinion, it's better to use the dynamic data or the quasi static? we are going to realize a quasi static test...

[Dharma]

I have done two kinds of simulation, one is quasi static and one dynamic. in the second one I have good deceleration data, but in the quasi static simulation I have a big peak of deceleration. I've red in the rules that we can use a filter...but in your opinion, it's better to use the dynamic data or the quasi static? we are going to realize a quasi static test...

[Bemo]

Best would be to understand why you have this peak in one simulation while the other one is fine. Maybe it's just a modelling error.

In general the dynamic simulation should be closer to the real case (if properly done). Some competition don't accept quasi-static tests anymore. I guess this is because there are effects which let the result differ from a dynamic test. Maybe the difference in your simulations has somethin to do with this.

[Dash]

I'll throw out a word that might let you know why. Strain rate. I worked in a lab that did testing on polymers ( rubber and plastic ) and the stress/strain curves are highly dependent on strain rate. That said, I have no idea what your material is but this could be a cause.
This is probably also the reason why the rules committee is trying to go to dynamic tests only.

[Kevin Hayward]

I think it is a shame that the rules committee is trying to go to only dynamic tests. There are many teams that have no access to dynamic test facilities. Without the option to build their own test rigs they must resort to the standard impact attenuator. This means they have no involvment with developing a crush zone, instead they get to experience a modern engineering exercise of buying off the shelf.

While the dynamic test is nominally more accurate there is available research in how to extrapolate quasi-static testing results into dynamic results. Possibly different energy absorption requirements should be met for different styles of testing, to account for the differences.

A while ago in FSAE there was no specific energy requirment of the crush zone. Teams instead had to show that their approach was valid. An energy requirment was later built into the rules. This meant teams had to test the IAs to show compliance. This almost certainly increased the resources and time allocated to this task, but also rewarded education outcomes by having teams actively design and develop a safety system. Now there is a push for tests beyond what is available to many teams worldwide, or choosing to go off the shelf. This effectively makes the default position "buy" instaed of "design".

The argument for this is that we must make these cars safe "for the children". Only the most deluded of rule makers would assume that changing from quasi-static to dynamic tests would considerably improve the safety of FSAE vehicles. It is a relatively minor effect in one potential "crash" situation. How about side impact for the low side chassis cars? How about side object intrusion on spaceframe cars?

If we want to look at some of the incidents at competitions we need to consider things like wheels coming loose and much bigger concern of fire. Why do we have rules that mandate a firewall and insulation between the driver and the fuel tank, but none between the fuel tank and the exhaust?

I'm not suggesting that we change these rules (except maybe a insulation and fire protection for the fuel tank) but it is pretty clear that a change to a dynamic test on the IA is overkill when compared to the overall safety rules on the cars. It is one area (and maybe th eonly one) that I think the US rules are currently better than the German ones.

Kev

[Dharma]

I agree with Kev...
infact we can't do the dynamic test, and if the quasi static test is allowed why won't we catch this chance!?

[Michael Royce]

The Formula Hybrid Rules still allow quasi-static testing!! And I will do my best to see they don't change it.