cage questions for DE car, possible club racer in near future
03-24-2006, 10:41 PM
#151
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Originally Posted by Geo
Um, yes, I'm relatively large. Currently 234.5 lbs (as of Monday) after losing 21 lbs. However, by the time my car is finished I expect to be 175 lbs or less.
Bro
03-25-2006, 12:31 AM
#152
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I'm doing weight watchers AND training for my next marathon. Who knew a moose could run a marathon?
My next marathon is in the middle of September and if I keep on my current pace (avg 3 lbs/wk) I'll be at my goal weight long before the marathon.
BTW, it has already taken a long time to finish the car. Being unemployed for 9 months in 2004 didn't help much.
My next marathon is in the middle of September and if I keep on my current pace (avg 3 lbs/wk) I'll be at my goal weight long before the marathon.
BTW, it has already taken a long time to finish the car. Being unemployed for 9 months in 2004 didn't help much.
03-25-2006, 08:46 AM
#153
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George - I'd reconsider the gusseted, kinked X (pyramid) - it offers quite a bit of spce, actually, and is an efficient design.
Of course, you'd need the Nascar setup if you were interested in IT (or is it ITS?)...?
Of course, you'd need the Nascar setup if you were interested in IT (or is it ITS?)...?
03-25-2006, 12:06 PM
#154
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Originally Posted by keith
George - I'd reconsider the gusseted, kinked X (pyramid) - it offers quite a bit of spce, actually, and is an efficient design.
Of course, you'd need the Nascar setup if you were interested in IT (or is it ITS?)...?
Of course, you'd need the Nascar setup if you were interested in IT (or is it ITS?)...?
The reason I'm thinking about switching to NASCAR bars is two-fold.
1) Based upon the FEA here it gives very nearly the performance of the pyramid while giving even more room.
2) Given my main hoop is set back from the door opening (it's even with the front of the rear seat), it will be easier to fab the NASCAR bars. I think I can redo my mounting plates so I can have a verticle reinforcement where the tubes would have to bend out.
Of course, before I do any of this, if Bro is willing I'd like to model the double bend it would require as well as the reinforced X I have in mind.
With my main hoop set back so far, the pyramid just isn't possible.
03-25-2006, 12:29 PM
#155
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Originally Posted by Geo
I am racing IT. NASCAR bars are not required for IT.
The reason I'm thinking about switching to NASCAR bars is two-fold.
1) Based upon the FEA here it gives very nearly the performance of the pyramid while giving even more room.
2) Given my main hoop is set back from the door opening (it's even with the front of the rear seat), it will be easier to fab the NASCAR bars. I think I can redo my mounting plates so I can have a verticle reinforcement where the tubes would have to bend out.
Of course, before I do any of this, if Bro is willing I'd like to model the double bend it would require as well as the reinforced X I have in mind.
With my main hoop set back so far, the pyramid just isn't possible.
The reason I'm thinking about switching to NASCAR bars is two-fold.
1) Based upon the FEA here it gives very nearly the performance of the pyramid while giving even more room.
2) Given my main hoop is set back from the door opening (it's even with the front of the rear seat), it will be easier to fab the NASCAR bars. I think I can redo my mounting plates so I can have a verticle reinforcement where the tubes would have to bend out.
Of course, before I do any of this, if Bro is willing I'd like to model the double bend it would require as well as the reinforced X I have in mind.
With my main hoop set back so far, the pyramid just isn't possible.
03-25-2006, 12:40 PM
#156
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Originally Posted by Geo
Of course, before I do any of this, if Bro is willing I'd like to model the double bend it would require as well as the reinforced X I have in mind.
Bro
03-25-2006, 12:41 PM
#157
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Originally Posted by complexx
I would think that if you have your main hoop set back the nascar bars would be more difficult to implement strongly (because of the double bend).
03-25-2006, 01:19 PM
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Here is what a Nascar bar REALLY is 
Bro, do you have Crash analysis software/add-ins at your disposal? It'll provide much more accurate information that can actualy be used. Otherwise, just make a small scale model and smash it it'll provide just as much or more info than the fea models you have shown.
Essentially, a lot of this work has already been done for us on a MUCH higher level, and we can use thier final products to build our own designs.
As we do not have the millions to spend on developing a $100k clubrace car, might as well use the 5+ million dollar programs that have developed race winning cars that meet and/or exceed current international safety requirements.
Bro, do you have Crash analysis software/add-ins at your disposal? It'll provide much more accurate information that can actualy be used. Otherwise, just make a small scale model and smash it
it'll provide just as much or more info than the fea models you have shown.Essentially, a lot of this work has already been done for us on a MUCH higher level, and we can use thier final products to build our own designs.
As we do not have the millions to spend on developing a $100k clubrace car, might as well use the 5+ million dollar programs that have developed race winning cars that meet and/or exceed current international safety requirements.
03-25-2006, 01:46 PM
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Originally Posted by 95m3racer
Here is what a Nascar bar REALLY is
Bro, do you have Crash analysis software/add-ins at your disposal? It'll provide much more accurate information that can actualy be used. Otherwise, just make a small scale model and smash it it'll provide just as much or more info than the fea models you have shown.
Essentially, a lot of this work has already been done for us on a MUCH higher level, and we can use thier final products to build our own designs.
As we do not have the millions to spend on developing a $100k clubrace car, might as well use the 5+ million dollar programs that have developed race winning cars that meet and/or exceed current international safety requirements.
Bro, do you have Crash analysis software/add-ins at your disposal? It'll provide much more accurate information that can actualy be used. Otherwise, just make a small scale model and smash it
it'll provide just as much or more info than the fea models you have shown.Essentially, a lot of this work has already been done for us on a MUCH higher level, and we can use thier final products to build our own designs.
As we do not have the millions to spend on developing a $100k clubrace car, might as well use the 5+ million dollar programs that have developed race winning cars that meet and/or exceed current international safety requirements.
The analysis I've been doing is comparative, not a quantitative point design. It is fine for answering such questions as "does a NASCAR type bar setup deflect as much as an X bar setup given certain boundary conditions". Granted, once everything goes beyond the yield strength of the material or results are extrapolated beyond the local effects the analysis becomes useless. But within the narrowly defined region of what we're looking at and how we are defining the designs and conditions it has applicability. BTW, I used to work for a company that built CART, Formula Atlanticand other race cars and am fully aware of the analysis that can be done to design safety systems including cages. And don't think it is all done analytically, i.e a design is created, analyzed, built and tested,analyzed again, fixed and then re-tested. A lot of designs are arrived at empirically, i.e.trial and error with analysis to point the way. That is why I have caveated what I'm doing here as I have in previous posts and firmly believe that the limited stuff here has some merit.
Bro
03-25-2006, 05:40 PM
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Some merit, yes. Its obvious you are no slouch in the engineering department. Mind me asking where you work(ed)?
However, we are not dealing with master fabricators 90% of the time, and we are also not dealing with engineering who are building the cages 99% of the time. So calculate the statistics on the knowledge behind the people usually building the cages, and you have a variable that puts all this analysis in the toilet. An example is a very basic understanding of load paths, and if you have ever been to a PCA/BMWCCA/SCCA/etc club race, its scary what some people are trusting thier lives with.
I'm moreso arguing on yourside, but you are analyzing something that while it looks nice on the computer screen, it still does not have a direct connection with what people are actually putting in thier cars.
If you can do an even 75% complete model of all the constraints that actually make a difference, and then generalize the unibody structure, you might be able to extrapolate some information to use for comparative reasons, otherwise you might as well just go with the engineering theory.
Now you also have to remember this is assuming you are trying for full cockpit antiintrusion, or you are building it do absorb impact to a certain extent and hope it does not get to the driver. Again, pretty much hundreds of variables, and nothing can conclusively be said for either design from the fea you have shown. But, it is a stepping stone for further research for whomever is interested, however there already is test data from these types of structures, and the results are in professional sports cars around the globe
However, we are not dealing with master fabricators 90% of the time, and we are also not dealing with engineering who are building the cages 99% of the time. So calculate the statistics on the knowledge behind the people usually building the cages, and you have a variable that puts all this analysis in the toilet. An example is a very basic understanding of load paths, and if you have ever been to a PCA/BMWCCA/SCCA/etc club race, its scary what some people are trusting thier lives with.
I'm moreso arguing on yourside, but you are analyzing something that while it looks nice on the computer screen, it still does not have a direct connection with what people are actually putting in thier cars.
If you can do an even 75% complete model of all the constraints that actually make a difference, and then generalize the unibody structure, you might be able to extrapolate some information to use for comparative reasons, otherwise you might as well just go with the engineering theory.
Now you also have to remember this is assuming you are trying for full cockpit antiintrusion, or you are building it do absorb impact to a certain extent and hope it does not get to the driver. Again, pretty much hundreds of variables, and nothing can conclusively be said for either design from the fea you have shown. But, it is a stepping stone for further research for whomever is interested, however there already is test data from these types of structures, and the results are in professional sports cars around the globe
03-25-2006, 06:22 PM
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Originally Posted by 95m3racer
Some merit, yes. Its obvious you are no slouch in the engineering department. Mind me asking where you work(ed)?
However, we are not dealing with master fabricators 90% of the time, and we are also not dealing with engineering who are building the cages 99% of the time. So calculate the statistics on the knowledge behind the people usually building the cages, and you have a variable that puts all this analysis in the toilet. An example is a very basic understanding of load paths, and if you have ever been to a PCA/BMWCCA/SCCA/etc club race, its scary what some people are trusting thier lives with.
I'm moreso arguing on yourside, but you are analyzing something that while it looks nice on the computer screen, it still does not have a direct connection with what people are actually putting in thier cars.
If you can do an even 75% complete model of all the constraints that actually make a difference, and then generalize the unibody structure, you might be able to extrapolate some information to use for comparative reasons, otherwise you might as well just go with the engineering theory.
Now you also have to remember this is assuming you are trying for full cockpit antiintrusion, or you are building it do absorb impact to a certain extent and hope it does not get to the driver. Again, pretty much hundreds of variables, and nothing can conclusively be said for either design from the fea you have shown. But, it is a stepping stone for further research for whomever is interested, however there already is test data from these types of structures, and the results are in professional sports cars around the globe
However, we are not dealing with master fabricators 90% of the time, and we are also not dealing with engineering who are building the cages 99% of the time. So calculate the statistics on the knowledge behind the people usually building the cages, and you have a variable that puts all this analysis in the toilet. An example is a very basic understanding of load paths, and if you have ever been to a PCA/BMWCCA/SCCA/etc club race, its scary what some people are trusting thier lives with.
I'm moreso arguing on yourside, but you are analyzing something that while it looks nice on the computer screen, it still does not have a direct connection with what people are actually putting in thier cars.
If you can do an even 75% complete model of all the constraints that actually make a difference, and then generalize the unibody structure, you might be able to extrapolate some information to use for comparative reasons, otherwise you might as well just go with the engineering theory.
Now you also have to remember this is assuming you are trying for full cockpit antiintrusion, or you are building it do absorb impact to a certain extent and hope it does not get to the driver. Again, pretty much hundreds of variables, and nothing can conclusively be said for either design from the fea you have shown. But, it is a stepping stone for further research for whomever is interested, however there already is test data from these types of structures, and the results are in professional sports cars around the globe
The key is what you said, "otherwise you might as well just go with the engineering theory." What I'm providing is a visual means of looking at the engineering theory.
The reasons for choosing different cage designs are not just predicated on which is the most efficient. Other factors like human factors, available space, fabrication capability, car interface and type of competition play into which design is chosen. I think what I'm doing is providing some engineering insight to some basic questions as to how certain designs work.
Since you asked, I happened to work for a while as a consultant and an employee of Swift Engineering. Swift website My real life jobs are in the aerospace (emphasis on space) field. Some of the stuff I worked on:
Know anyone that is hiring in SoCal?
Bro
03-25-2006, 07:39 PM
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Awesome, I'm talking with a company in NJ right now about an aerospace ME position.
Thanks for the reply, and glad we're in agreement.
And you hit it on the head, "fabrication ability" is a big factor. If you cannot handle complex sheet metal gussets, do something thats feasible and can be properly done. Nothing worse than a cage thats intended to be "fancy" and is constructed horribly.
Thanks for the reply, and glad we're in agreement.
And you hit it on the head, "fabrication ability" is a big factor. If you cannot handle complex sheet metal gussets, do something thats feasible and can be properly done. Nothing worse than a cage thats intended to be "fancy" and is constructed horribly.
