UW-Madison Complete Frame Pictures

[Lyn Labahn UW-Madison]

I thought I would post a few pictures of our completed frame, and a few snapshots of the construction process. You can check them out here:

Frame Picture Directory (http://www.cae.wisc.edu/~sae/frame/)

The pictures are definately NOT dialup friendly, I could resize them if someone cannot view them because of the size, I assume most of you are on some sort of broadband.

A few specs if interested:

4130 Chromoly Space Frame front and rear
7075 Aluminum Monocoque Center Section
Weight: 61 lbs
Expected Rigidity: 2000+ ft*lbs/degree


The aluminum monocoque can be a real bitch at times, but it is "free" body work in the center of the car, stiff as hell, and provides a comfy cockpit for the driver. As far as I know, we are the only school in the past 4 years to run one.

Feel free to ask if you have any questions.

[Lyn Labahn UW-Madison]

I thought I would post a few pictures of our completed frame, and a few snapshots of the construction process. You can check them out here:

Frame Picture Directory (http://www.cae.wisc.edu/~sae/frame/)

The pictures are definately NOT dialup friendly, I could resize them if someone cannot view them because of the size, I assume most of you are on some sort of broadband.

A few specs if interested:

4130 Chromoly Space Frame front and rear
7075 Aluminum Monocoque Center Section
Weight: 61 lbs
Expected Rigidity: 2000+ ft*lbs/degree


The aluminum monocoque can be a real bitch at times, but it is "free" body work in the center of the car, stiff as hell, and provides a comfy cockpit for the driver. As far as I know, we are the only school in the past 4 years to run one.

Feel free to ask if you have any questions.

[Charlie]

So is the weight of the bodywork the main benefit to the aluminum monocoque section? What are the other benefits vs a complete space frame?

Just curious because our frame last year was 61 lb and physically tested to 1968 ft/lbs deg, and we considered it a bit heavy for the rigidity. Then again we had bodywork on the sides that added a few lbs.

-Charlie Ping

I just need enough to tide me over until I need more.

[Denny Trimble]

Looks good Lyn! I have a few questions (just curious):
What's the camber change rate in bump on your rear suspension? Looks to be very high!

I like the engine bay triangulation.

Where do your shocks mount in the front?

University of Washington Formula SAE ('98, '99, '03, '04)

[vinHonda]

we run carbon panel on our centre section, and have for the past 2 years. Our frame w/ panels and weld on tabs weighed 52-55 odd pounds... depends on what else you include. Should have our car hit the ground running on monday.

Vinh

University of Toronto Formula SAE Racing Team
www.fsae.utoronto.ca (http://www.fsae.utoronto.ca)

[Lyn Labahn UW-Madison]

Charlie,

A few quick benefits off the top of my head:

Increased Safety as compared to baseline structure in the rules, nearly 3x energy absorbtion capability!

The hollow sections allow for relatively moisture and debris free area to store many items: battery, ECU, majority of wiring, shifting system, wireless modem etc.

Ease of use for floorpan and firewall as stressed members.

Uniqueness.

Freedom of design between front and rear sections of the car.

The bulkhead allows for there to be a node anywhere on the rollhoops from the space frame section. Negating the need to triangulate with other members.



A note on weight, this years frame was slightly overbuilt, as it was a first year attempt for the designers. We are confident that by next year, we should be able to get it in the mid fifties without sacrificing much, if any rigidity.

[Lyn Labahn UW-Madison]

Denny,

The shocks will mount on the front lateral bar that runs about an inch above the monocoque as seen in finished picture one. You might be cringing because there is no node in the center of the tube, however this is going to be addressed with a special bellcrank mount, and steering mount.

The entire car is running a suspension that while it is sound on paper, is definately a gamble in practice. Upon recieving some tire data from goodyear, the suspension boys decided to roll the dice a bit with these points. There is nearly no static camber, with lots of dynamic gain built into them as you noted. We are eagerly awaiting testing to find out how they perform, they have stiff competition as our 2003 car points handled fantastic and won skidpad at competition!

[jack]

great frame, very original approach! it even hints of the wwu car http://fsae.com/groupee_common/emoticons/icon_wink.gif
i would just like to add that one of the reasons we went with tubes is because they make an excellent crush structure.

http://dot.etec.wwu.edu/fsae/pages/V35%20Chassis_jpg.htm

i cant remember frame weight right now, but its mid fifties i believe. im not going to do any stiffness bragging until it is accually measured...it should be high http://fsae.com/groupee_common/emoticons/icon_wink.gif

jack @ WWU
http://www.etec.wwu.edu/

[Denny Trimble]

Yeah, we're going the "torsion box" route this year as well. I'll post pictures as soon as it's together... final part layup should be done tonight and everything assembled by the weekend!

University of Washington Formula SAE ('98, '99, '03, '04)

[Lyn Labahn UW-Madison]

Thanks for the kind words, and I can't wait to see the pics Denny.

[RagingGrandpa]

I'm very interested in how you're getting your torsional stiffness numbers. Have you run FEA on the chassis alone, and what points did you constrain or force?

Big torsion numbers fly around alot, but most of the time it's apples to oranges. If you could give more details I'd be very appreciative.

"...with powershifts and tiresmoke for all"

[Jackson]

Silly question....

what are those porcupine thingys sticking off of the aluminum panels in all of the construction pictures?

Something to do with rivets?

Brian
Washington State U FSAE

[Marc Jaxa-Rozen]

They're clecos that fasten into rivet holes and temporarily hold the sheets together before you do the final riveting.

Marc
École Nationale d'Aérotechnique

[Lyn Labahn UW-Madison]

Jackson,

Marc hit it on the head, they are Clecos. You first drill out all of the holes that you are going to rivet to 3/32 and put the silver 3/32 inch clecos in. Then make sure all of the structure is aligned. Next all of the holes are drilled out to 1/8th of an inch and 1/8th clecos are inserted. Lastly, you take apart the whole structure, put epoxy into the laps, place as many clecos as you have all over the structure and rivet.

Raging Grandpa, once I run the the torsion test, I will post some pictures and results.

[breathes fire]

[QUOTE]Originally posted by Lyn Labahn UW-Madison:

<<<The entire car is running a suspension that while it is sound on paper, is definately a gamble in practice.>>>

Regarding your rear suspension.

Your team obviously takes camber gain very seriously. It appears that your front view virtual swing arm lengths are somewhere around 3/4 of the car's track width. With this arrangement I'm guessing that your roll center will remain firmly planted on the centerline of the chassis, which is good. But it will migrate vertically with chassis movement ALOT; probably at a rate higher than the chassis ride height change itself, which will vary the roll moment with ride height changes. It's probably not enough to worry about, BUT the killer is going to be the excessive scrub and cambered wheels with squat. This won't be your friend when braking into a turn or powering out of it.

Remember with suspension that everything is a compromise and too much of any parameter is usually a bad thing. A good rule of thumb for front view swing arm lengths is twice the track width; maybe a bit shorter for SAE cars because they turn so often.

Anyway, good luck with it. I think as long your suspension gurus choose a spring/shock package that restricts movement to within a narrow window you should be fine.

Back to the dungeon..

[David Kieke]

Just a quick note on Wisconsin's recent history. They finished second in 2000 and 2002, fourth in 2001, and 28th in 2003 (due to Endurance issue). They also won skidpad in 2003 and came in second in 2002. They have generally had a very respectable car in recent years as well as a very knowledgeable team.
I would say that their suspension has been working pretty well overall.

Good Luck