Question about forces in Chassis.

[Necrobata]

Howdie mates.

We`ve been lately checking on the rules that affects the incoming structural report.

While working on Soliwork over the main roll bar, we applied the strength required by the rule AF4.1.1 in the main and bulkhead, and it shown a security factor REALLY low.

Question: Does it must be a force applied on one spot, the top point, or it can be applied evenly on the top surface of the main roll bar???

Results shown us that if we use a puntual force on the top chassis it gets massive deformation while applying evenly on surface it give us a decent security factor, so we are kinda confused about what the rule ask us.

Also another question. The bracings supporting the main roll bar, they have a certain separation, applying the force in the top gives us the low security factor but, putting them even closer shouldnt distribuite the forces even better??? because we did both simulations and the results were the same, it makes me wonder, is it possible, in your opinion that the solidworks isnt simulating properly? like not identifying the bars behind the main? has anyone been in this situation?

Last question, the force applied in the main is in the order of the 5, 6 and 9 KN but the force to be aplied in the bulkhead is 150KN in one point, that destroys our car, is it really that big?

Thanks for the future replies, no jokes plz we are in a bit of a hurry.

[Necrobata]

Howdie mates.

We`ve been lately checking on the rules that affects the incoming structural report.

While working on Soliwork over the main roll bar, we applied the strength required by the rule AF4.1.1 in the main and bulkhead, and it shown a security factor REALLY low.

Question: Does it must be a force applied on one spot, the top point, or it can be applied evenly on the top surface of the main roll bar???

Results shown us that if we use a puntual force on the top chassis it gets massive deformation while applying evenly on surface it give us a decent security factor, so we are kinda confused about what the rule ask us.

Also another question. The bracings supporting the main roll bar, they have a certain separation, applying the force in the top gives us the low security factor but, putting them even closer shouldnt distribuite the forces even better??? because we did both simulations and the results were the same, it makes me wonder, is it possible, in your opinion that the solidworks isnt simulating properly? like not identifying the bars behind the main? has anyone been in this situation?

Last question, the force applied in the main is in the order of the 5, 6 and 9 KN but the force to be aplied in the bulkhead is 150KN in one point, that destroys our car, is it really that big?

Thanks for the future replies, no jokes plz we are in a bit of a hurry.

[Pete Marsh]

Alternative frame rules are not meant to easy.
You must have some reason for going that way, composite hoop perhaps?
I thought physical validation of you simulations was a requirement of the procedure? Wouldn't you do that before designing the chassis?

The loads seems appropriate to me, load of around 50G. The impact attenuater is allowed a peak of up to 40G.

Good luck,
Pete

[Necrobata]

The hoop was actually one continuos tube, but with that shape, the Security factor was 0.01, when we made it composite (being composite the union of various forward tubes) the factor went up to 0.3 :S

My guy from chassis doesnt get why, the hoop as it is wich looks like any other Main hoop has that little resistance.

:S

[typeh]

first u will be asked this if work on alternative frame rules, ask ur self why u moved to alternative frame rules

try bracing starting from most top surface of main hoop.

Which competition are you going to participate in?

AUMotrosports
FSG 2012
Design team head