cage questions for DE car, possible club racer in near future
03-17-2006, 04:07 PM
#46
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Actually, I'm modelling this with shell elements in order to be able to apply loads in different places along the tubes. I thought about modelling with beam elements (and probably will as a sanity check), but I'm going to plunge ahead with shell elements. Adding the gussets won't be a problem. What are we talking for material thickness of the gussets?
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03-17-2006, 05:31 PM
#49
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I am in the non flat X camp. All are also leaving out the weld in compression or tension factor. I would rather have a man made fitment in compression than tension. One factor that the nascar bars have is that the load absorbtion starts further away from you than in a flat X.
03-17-2006, 06:39 PM
#50
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Originally Posted by kurt M
I am in the non flat X camp. All are also leaving out the weld in compression or tension factor. I would rather have a man made fitment in compression than tension. One factor that the nascar bars have is that the load absorbtion starts further away from you than in a flat X.
03-17-2006, 07:38 PM
#51
Drifting
If the corner of a car or Armco hits the pyramid X other than perpendicular, the tubes will be in tension rather than compression. They are only in compression if the contact is at the center of the X and relatively perpendicular.
03-17-2006, 08:11 PM
#53
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Are those flat plate gussets between tubes? Hard to tell from the picture.
If so, what's the advantage of those over the tacos?
If so, what's the advantage of those over the tacos?
Originally Posted by Cory M
complexx-
Here is a picture of the gussets you're refering to (on a 997 cup).
Here is a picture of the gussets you're refering to (on a 997 cup).
03-17-2006, 08:14 PM
#54
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There is no advantage of flat panal gussets over tacos other than weight. The tacos will be stronger because its essentially 2 gussets.
*Edit
Thats assuming your comparing flat panal gussets and tacos of the same thickness material.
*Edit
Thats assuming your comparing flat panal gussets and tacos of the same thickness material.
Last edited by complexx; 03-17-2006 at 09:43 PM.
03-17-2006, 10:58 PM
#57
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Great discussion. Differences of interpretation of not only design but reactions to a crash as well. Plenty to think about and everyone is playing nice. Lots to learn here. John has me looking at some things a little differently now and while I haven't changed my mind yet, it certainly has opened it some more.
I'm looking forward to the FEA.
I'm looking forward to the FEA.
03-17-2006, 11:01 PM
#58
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Originally Posted by Cory M
I don't think it's that simple. The loads will travel through the tubes depending on the angle and location of the hit, most likely some of the tubes will be in compression and some of the tubes will be in tension. There is an infinite number of possible crash scenarios, the key is to choose the design with the best all around performance.
03-17-2006, 11:10 PM
#59
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I'd say the most useful scenario would be an impact that is directly perpendicular to the length of the vehicle (t-bone). This way the largest component of the force from the impact is being placed on the cage tubing. Any angular strikes away from perpendicular and your adding in complexity. I think a basic analysis in FEA will be the most useful (even though it ignores lots of other variables that are very important).
03-18-2006, 06:39 PM
#60
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Originally Posted by complexx
There is no advantage of flat panal gussets over tacos other than weight. The tacos will be stronger because its essentially 2 gussets.
*Edit
Thats assuming your comparing flat panel gussets and tacos of the same thickness material.
*Edit
Thats assuming your comparing flat panel gussets and tacos of the same thickness material.
I was ready to launch, but you saved yourself with the edit. The type of gussets the cup cars use do indeed offer much more strength. A taco or flat sheet gusset only adds tension strength. If you took two tubes, welded them together to form a 30 degree V (like half an X), and added a taco, this reinforcement would only help if you grabbed both ends of the tubes and tried to pull them apart in opposite directions, in plain with the V. The taco would be in tension, and would resist that force.
The Cup Car type are rolled and formed gussets. They create a beam structure at the corner where they are located which offers the same tension load resisitance, as well as a fair amount of TORSIONAL resistance as well. Not only would these gussets resist the same load previously described quite well, but they would also resist the torsional load if you grabbed each end and pulled them in different directions, lateral to the V.
The Cup Car type are a bit difficult to render, but it is worth the effort. 2 loads resisted with one type of gusset, with no extra weight. That is called WIN-WIN! I'd use minimum 16g sheet, I'd guess.