Lightening Holes: just cool or functional

Littleman = Hamtastic

 

Damn, dude!

 

No worries. Just go smaller on the holes and use a little thicker walled tubing to weld in your ports. Maybe 1/8" wall. You'll be alright!

For those of you with 2x3 frames that are ported, what have you guys used? Help this guy out.

 

WHOA! great minds must think alike... I've been teaching myself COSMOSWorks this morning so I could do the exact same thing! All I got done was the no-holes version, but since you beat me to it I think I'll stop at that.

 

Cool! Which version are you using? I'm a little behind. I'm still using 2005 2.0. Cosmos is a good checker for hypothetical situations. It's not always easy to read and sometimes it's really hard to simulate exactly the situation you want, but for the most part it's very helpful. Thanks for posting that.

What size was the load you applied? Also what size was that stuff?

 

No dont stop, you might as well just model the whole frame, including cross members, z-ed rear etc. This is awesome to see where all the stresses are. It looks like your test rail shows a uniform load, but wouldnt it be fulcrums at the front and rear axles, and point loads on the motor /tranny mounts and the mounts for the body?

 

I used 2x4" rectangle with 1/8" wall and 100" long. 1000 lb distributed force.

I've got Solidworks 2006-2007 student edition with COSMOSWorks, COSMOSMotion and COSMOSFlowWorks. Normally $200, but I got it free through my school!

 

I've got one. I'll dig it up. It might be modeled at home though. Either way I'll get one up.

The nice thing about the student edition is you can do assemblies. The full vesions only allows parts files to be tested. Is that still true?

 

It's a geek magnet for sure.

 

COSMOSXpress will only let you do parts, and that comes with Solidworks, you can buy COSMOSWorks extra and you can do everything with it, but its $$$$$. Soliworks student edition comes the same way, $100 for regular, then $200 with all the COSMOS stuff. Its way more program than I'll ever be able to take full advantage of.

 

Okay, more ultimate nerd stuff...

This frame is not 100% correct. Wasn't intending on doing stress studies on it either, so the stresses are a little off.

Anyway, this is a 2x4 frame with ports as you can see. I allowed 1000 pounds for engine and transmission loading to the normal three mounting points as well as a distributed load over the center cross members and side rails to represent a 400 pound body. I did not take into account the linkage for the front and rear or panhards, things like that.... yet. Maybe in future stuff, but not right now. Anyway, here ya go... more "just for fun" stuff. Also the frame is about 6 inches wider than what it should be and the front crossmember is just all wrong (shape, angle, etc.)


Now the stress study (all static driveway stuff)



Gives a good idea where the stresses are anyway. Sorry so dark. Need to figure out how to change the colors during the study so it's easier to see.

Maybe this will help someone.

 

wow!, glad i read the whole post.....

 

Ha! wada ya mean?! If we had talked about this kind of stuff in math class I may have payed attention. I can relate to these calculations

And for the record, I SUCK at math, and have to records to prove it

But this thread is neat, and I'm actually following the calculations! Thats scary...

 

Wow that was fast. You are a super-nerd! haha
looks like most of the stress is on the rear spring perch and front crossmembers and not really even affecting the drilled 2x4. Maybe there is a good reason for parallel leafs and coil overs, IFS after all!

 

When I said it was a geek magnet, I was painting myself with that brush too. It is a very interesting thread.

 

Yes, true! However, these small early cars are so light that it doesn't really make that much of a difference with a good frame.

Yeah, that front cross member is all wrong. I was originally thinking some heavy C-channel and some gusseting, but it really needs to be better than that with a Hemi bolted in there and a heavy spring. The rear isn't quite calculated right either, but it's close. The safety factor was an easy 3 and realistically closer to 4.

When I get the REAL frame drawn up I'll post it. It will have more realistic dimensions, mounts and by then I may have some calculations done so I can apply the forces to the 4-bar and split bone mounting points. Lot of littel details to figure out. Need to think of it in a dynamic/driving state also. Lots of work.

Anyway, point of this whole thread is that lightning holes look rad and can also be structurally functional with tubes welded in. Not saving much on weight with the tubes welded in, but it does look cool and keeps crap out of the frame.

Cheers!
Scooter the super Nerd... [picturing pocket protectors and calculators right now]

 

At least someone loves Nerds!

 

I'll bet she has cavities......

 

yeah...me too.

 

So my recent trip to the airshow got me thinking...
Has anyone ever built and I-beam frame? Would it be possible, or would it be too weak like an unboxed original model a frame? If the web was thicker maybe? In that case the lightnening holes would be functional and you would be using less steel because you have an "I" section instead of 4 walls, and you wouldnt have the problem of leaves and water getting trapped inside...

Anyone???? Engineers?????

I realize you would have to account for the twisting etc. but could that be handled with cross members?

 

Maybe if you boxed one side you could pull it off. You would have to have a really thick web, flanges and gussets galore and definitely some serious crossmembers. It could be done, but it would take some beefy structural beam to do it. Square or rectangular is a far better choice. You don't want your doors popping open on every pot hole you hit...

There's definitely a reason we box our frames!

 

Funny, four years (or so) ago I had this idea, and how to make it, for my buick roadster. but the construction method I had in mind would be a TON of labor and time, so I went with some trusty/rusty/ holey deuce rails we had layin' around.

My idea was of course two belled hole boxing plates welded bnoth at the mating edges of the belled holes and plug welds with spacers matching the "gap" created by the belled holes.

then adding a strip of 2"x12'-10ga., welding that along both boxing plates and dressing smooth so it appears stamped,

After all of that work (48 feet @ roughly 5min. per inch in dressing the welds) take some 1/4" or 3/8" x 2" add that to the top, drilling a 9/32" hole every 1 1/4" on both sides of the boxing plates and hot riveting the plate to the rails, top and bottom....

I can't believe I just exposed my "super top secret" to the world, but if you have the time to do it, take pictures!!haha

I forgot to mention the shaping of the rail and how you would have to adjust the holes so they still line up (inside and out, ya dig?)....



But I'm Polish.....I'm sure there is another way

 

The idea of having open holes in your frame got me thinking about replacing this one guys shocks in a mid 80's Ford. Ford had some larger holes cut in the unibody rails over the rear axle. I noticed something protruding from one of the lowest holes so I pulled it out -- a walnut. Another rolled into place -- I pulled maybe 10 walnuts out of the guy's frame, guess he had a squirrel getting into his garage and thought it would be a good place to store his cache

 

Holy Crikey, how do you Newbies find these threads. HAHA.