Digital Chassis Design

[jbtill12]

Does anyone have a sample of a digital chassis in either AutoCAD, Solidworks, SketchUp, or a similar software. I have started on one in sketchup and I am about half way through with it but also wanted to see what other builders were using to design new cars. Looking to try ideas before we build it. Also any digital parts like rear ends, shocks, springs, etc?

[zeroracing]

I am interested in doing one also, guess not many people have done it. Post a pic of your design so far, lets see what sketch up can do.

[racin6mod]

sketck up is more like solidworks than autocad in my oppion.I have used it for a 3D project it just takes more time than autocad.you might try afco call them and see if they'll send you a pdf file of the parts you want to use on your chassis.

[F22 RAPTOR]

Is sketch up a form of FEA(Finite Element Analysis)? I'd love to have access to some software like that. I'm looking to build a less flexible chassis as I'm convinced most cars built today are nothing but chrome-moly noodles.

[racin6mod]

Sketch up is a free down load from google it's like solidworks starter program.but you can do quit a bit with it.ther is an upgrade you can also get that makes it even better.

[Egoracing]

Anyone remember the GRT "computer car"? They spent a TON of time and money to computer design a car that would eliminate flex. It was supposed to make all the adjustments more repeatable and consistent. to but it bluntly the car SUCKED! All they really accomplished was they proved that in a dirt application the chassis has to flex to be able to keep traction.
The surface that we all race on and love is to inconsistent and have WAY to many variables to be able to run a rigid chassis. What do you think a cup car would do on dirt? Ever seen the Arca cars on dirt? Ever wonder why Nascar quit running on dirt? What happens when you take an asphalt 3 link modified and try to run it on dirt? Asphalt cars are built to stiff and that kills there performance on dirt, they are slow and the race is not that interesting.
Do some research and you will find that it has already been tried several times and all have failed. I guess it just proves that history does repeat itself.

[rmrc]

It may be time to revisit the reduced flex possibilities. Granted Garrison's car was only a few years ago but todays spring and shock combinations have changed the playing field. The computer car may have been born too early! My feeling is that if your car needs to flex, it's probably sprung too stiff.

[Egoracing]

The most important reason for it to flex is energy dissipation. Nascar tried to build STIFF cars and drivers paid the price until they started building them to flex more.
If the tracks were smooth and consistent I would agree but they are not and there needs to be some "give" somewhere to make the cars drivable. I have friends that build multi championship asphalt chassis and road racing chassis, there dirt cars that they build are specifically redesigned to allow flex as without they did not work.

[F22 RAPTOR]

Anyone remember the GRT "computer car"? They spent a TON of time and money to computer design a car that would eliminate flex. It was supposed to make all the adjustments more repeatable and consistent. to but it bluntly the car SUCKED! All they really accomplished was they proved that in a dirt application the chassis has to flex to be able to keep traction.
The surface that we all race on and love is to inconsistent and have WAY to many variables to be able to run a rigid chassis. What do you think a cup car would do on dirt? Ever seen the Arca cars on dirt? Ever wonder why Nascar quit running on dirt? What happens when you take an asphalt 3 link modified and try to run it on dirt? Asphalt cars are built to stiff and that kills there performance on dirt, they are slow and the race is not that interesting.
Do some research and you will find that it has already been tried several times and all have failed. I guess it just proves that history does repeat itself.

My personal opinion is the, "Computer car" was the wrong suspension combined with a somewhat rigid chassis. Todays 4 link suspension with progressive spring indexing is to aggressive for a rigid chassis. I think a swing arm or other linear type suspensions would be better suited for a rigid platform. JMO

[rmrc]

Raptor nailed it. We might build a "somewhat" rigid chassis and that's probably all that we can hope for. Some of the cars currently being built need to be re-welded waaaaay too frequently. That tells me that the chassis is now a big variable in the suspension system. That's something that cannot be put on a dyno and rated. You cannot quantify a chassis that has turned to jello! Protecting drivers by designing crush zones is something that has been done for years. Somewhat rigid works for me....

[Ghopper]

[QUOTE=rmrc;1301804]Raptor nailedThat tells me that the chassis is now a big variable in the suspension system. That's something that cannot be put on a dyno and rated. QUOTE]

Yes it can be "dyno'ed".

To address the negative computer design comments - Computer programs are used to gain understanding of the design of a widget, the operator designs the widget.

The 3D drawing software will be good for previewing a design and test fitting components. To go into a finite element study would be another level. I think the most insight for the effort would be a simiple beam element model. You would assign cross sectional properties to the stick model you create. The joining nodes would be assumed almost rigid. A more detailed model could be made with to the detail of weld penetration, but I dont think most of us will want to invest the time or have the experience to build a good model.

I have a variety of Catia V5 geometries that I have created only for visualization to a multi-body model. None are very sexy and they are saved as a .CATPart


Ghopper

[fastford]

[QUOTE=Ghopper;1301932]

Raptor nailedThat tells me that the chassis is now a big variable in the suspension system. That's something that cannot be put on a dyno and rated. QUOTE]

Yes it can be "dyno'ed".

To address the negative computer design comments - Computer programs are used to gain understanding of the design of a widget, the operator designs the widget.

The 3D drawing software will be good for previewing a design and test fitting components. To go into a finite element study would be another level. I think the most insight for the effort would be a simiple beam element model. You would assign cross sectional properties to the stick model you create. The joining nodes would be assumed almost rigid. A more detailed model could be made with to the detail of weld penetration, but I dont think most of us will want to invest the time or have the experience to build a good model.

I have a variety of Catia V5 geometries that I have created only for visualization to a multi-body model. None are very sexy and they are saved as a .CATPart


Ghopper

yea right

[raceman17]

I have Solidege and Solidworks with FEA analysis capabilites. I could run your model if they are drawn correctly. Let me know if you want to try it.

[F22 RAPTOR]

Raptor nailed it. We might build a "somewhat" rigid chassis and that's probably all that we can hope for. Some of the cars currently being built need to be re-welded waaaaay too frequently. That tells me that the chassis is now a big variable in the suspension system. That's something that cannot be put on a dyno and rated. You cannot quantify a chassis that has turned to jello! Protecting drivers by designing crush zones is something that has been done for years. Somewhat rigid works for me....

Cool! Do you have a website for your cars?

[RCJ]

That is a good piont that different suspensions might need different degrees of flex.I've always felt that that a flexible car had a wide sweet spot but was a little slower.A stiff car was faster but harder to setup and easy to miss.If I were building a car for customers it would be a flexible car that was easy to setup and work good on a lot of track conditions.My own cars have always been stiffer.