Roll cage design loads?
Roll cage design loads?
(OP)
I'm designing a roll over protection system for my personal pickup truck and would like to know what loads I need to design to.
I started with a CAD model for the connection points and packaging. I then modeled the design in Femap using line elements representative of the tubing cross-sections.
Now I'm stuck thinking of how to load the model to asses it. Are there automotive standards for roll over protection and if so what are they? This is not in my industry.
I started with the vehicle weight as a static load on the sides and top in which it is well under yield. I then assumed an impact at 40 mph with a 12 inch deflection which gave me a load of around 300,000 lbs. Using this as a static load overwhelms the structure. Can someone point me in the right direction?
I started with a CAD model for the connection points and packaging. I then modeled the design in Femap using line elements representative of the tubing cross-sections.
Now I'm stuck thinking of how to load the model to asses it. Are there automotive standards for roll over protection and if so what are they? This is not in my industry.
I started with the vehicle weight as a static load on the sides and top in which it is well under yield. I then assumed an impact at 40 mph with a 12 inch deflection which gave me a load of around 300,000 lbs. Using this as a static load overwhelms the structure. Can someone point me in the right direction?





RE: Roll cage design loads?
Start by getting the index, which I think no longer fits on a CD.
According to an old friend who was a part-time steward at the Mt. Clemens, MI dirt track,
their local standard for roll cage assessment included vigorous application of a heavy sledge, anywhere and everywhere, and visual examination for yield, and especially weld cracks.
Mike Halloran
Pembroke Pines, FL, USA
RE: Roll cage design loads?
RE: Roll cage design loads?
I witnessed this slow speed rollover on a rock face where the 4 point attached roll bar had two of the roll structure feet go through the floor to be stopped only by the leaf springs directly below. The failure mode was a combination of the 1/4" roll plate foot shear cutting through body sheet metal and body spot welds tearing apart. Driver was very lucky to have no injuries.
Ron Fournier's Metal Fabricators Handbook who has an extensive history in race and specialty car construction is somewhat dated, but a worthwhile read.
https://books.google.com/books/about/Metal_Fabrica...
RE: Roll cage design loads?
The roll bar must be capable of withstanding the following stress loading applied simultaneously to the top of the roll bar: 1.5 (X) laterally, 5.5 (X) longitudinally in both the fore and aft directions, and 7.5 (X) vertically, where (X) = the minimum weight of the car
RE: Roll cage design loads?
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Roll cage design loads?
The fabricator is a desert race guy and pointed me towards the SCORE rule book. They are very simplistic, with a main tube size specified by the vehicle weight. The max being 4k lbs. There are also general design guidelines, but these apply to a full cage, not just a functional roll bar.
http://score-international.com/raceinfo/wp-content...
Mr168, I'll give your loading cases a whirl and see how my design does. I trust the SCCA would be able to spec out roll bar properly.
RE: Roll cage design loads?
You might be able to detect cracked welds from the sound you hear but any purpose other than that seems like a waste of time.
RE: Roll cage design loads?
FIA WORLD RALLY CHAMPIONSHIP
http://www.fia.com/regulation/category/119
-Dave
NX 9, Teamcenter 10