Time Line Chassis

[Lash]

Hey guys (and maybe gals),

I was trying to get an idea of how far most teams are with chassis fabrication. Let me know how far you are or what you have accomplished so far. Also what kind of materials are you using for the chassis?

[ReadySetGo]

We are finishing up the analysis right now. We should be getting close to jigging it up within a month or so and welding it shortly after. We are making ours out of 1020 dom and using regular wire feed MIG. Frame weight is around 60-70lbs. Partially stressed motor and torsional rigidity around 2500lb-ft/deg. We should have bending, shear, polar moment, and natural frequency shortly.

Our main goal is to have something running by late January, early feb! So get your ball rollin man!

hope that helps....frame guy should be really close with the suspension guy! You should be building your frame around the suspension points, not vise versa!

[Lash]

What did you do your FEA in ?? Thanks for the info.

[Paul V.]

We're about 30% into Chassis iterations. Hope to be construting in a month.

Paul
UAH FSAE

[Matt Gignac]

FEA more or less done (70 some odd torsional rigidity anlyses, a few in bending, some analyses getting started for brackets, mounts, etc).

Right now we're designing the jigs we'll need for tube cutting, frame welding.

We're just waiting for a few final shock dimensions to finalize the design, and then construction can start.

Matt G
McGill Racing Team

[ReadySetGo]

We're doing priliminary FEA in Cosmos for brackets and localized areas, and doing the full frame tests in Algor.

[Ben Beacock]

4130 just came in today, so we'll be bending the hoops on the weekend and starting construction.

[Lash]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Ben Beacock:
4130 just came in today, so we'll be bending the hoops on the weekend and starting construction. <HR></BLOCKQUOTE>

Ben, may I ask why you chose to use 4130 (cormolly right??). We studied the difference between 4130 and 1020 and the price was almost double and the ultimate yield strength was almost the same. Correct me if i'm wrong. Thanks.

[Lash]

Oh, also I wanted to know where did you learn about space frame chassis. I've being reading lots of books on chassis principals and the books mostly outline suspension, steering, and tire control. Please list some contacts, web pages, books, or ideas of where you got your information on designing a tube frame chassis. Thanks alot! http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Tidexcab99]

Lash, last time I checked the Ult. yield strength of 4130 steel is about 1.5 times greater than mild steel. What value did you get for the yield strength? Also, can you get mild steel in wall thicknesses of 0.035" and 0.028"?

[carts]

The major problem with 4130 is that all the welds need heat treating to stress relive them. If you do not select the correct weldment filler and use a high nickel stainless filler it does not like being heat treated. There is no doubt it is good stuff, we used 4130 for our space frame last year and it was excellent to weld up but you need the heat treatment to fully utilise the materials properties add this on to the already expensive cost of the material means you are left with a vary expensive chassis..

[Ben Beacock]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Tidexcab99:
Lash, last time I checked the Ult. yield strength of 4130 steel is about 1.5 times greater than mild steel. What value did you get for the yield strength? Also, can you get mild steel in wall thicknesses of 0.035" and 0.028"? <HR></BLOCKQUOTE>

Thats just it.. you can get .035, and we use alot of it, in varying diameters. Granted, much of the chassis isn't highly stressed but the difference in the cost report isn't that much. say a heavy 100lb chassis. thats $60 for 4130 vs $30 for mild steel. I also feel better knowing I have a 4130 main hoop over my head vs a mild steel.
As for heat treating: I don't beleive its necessary(with ER70S-2 filler, or similar). some welds may need to be stress releived if you've put too much heat in there, but otherwise nothing is needed.
A-arms are different (since they see so much stress), and we'll most likely use 4130 filler and do a full heat treat.

[Lash]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Ben Beacock:
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Tidexcab99:
Lash, last time I checked the Ult. yield strength of 4130 steel is about 1.5 times greater than mild steel. What value did you get for the yield strength? Also, can you get mild steel in wall thicknesses of 0.035" and 0.028"? <HR></BLOCKQUOTE>

Where are you getting these prices? For the whole chassis $60 ??? Show me were and I'll sign !!! Sounds ridiculous if you ask me.
Thats just it.. you can get .035, and we use alot of it, in varying diameters. Granted, much of the chassis isn't highly stressed but the difference in the cost report isn't that much. say a heavy 100lb chassis. thats $60 for 4130 vs $30 for mild steel. I also feel better knowing I have a 4130 main hoop over my head vs a mild steel.
As for heat treating: I don't beleive its necessary(with ER70S-2 filler, or similar). some welds may need to be stress releived if you've put too much heat in there, but otherwise nothing is needed.
A-arms are different (since they see so much stress), and we'll most likely use 4130 filler and do a full heat treat. <HR></BLOCKQUOTE>

[Lash]

For some reason it quoted the wrong guy. I was asking Ben where he got these prices from. Let me know who your supplier is !! I'm in Windsor and prices are over 10 times that here!

[Didier Beaudoin]

I beleive Ben was talking about the cost you have to write down in the cost report. No one gets 4130 at that price. It cost us over 400$ this year for our tubing, and it was a good price already! http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

[CAV]

Can you list a reference where you got this idea? You do not need to heat-treat 4130 if it's thin gauge and you used ER80S filler. Check out this link from Lincoln Electric:

http://www.lincolnelectric.com/knowledge/articles/content/chrome-moly.asp

On our 4130 FSAE parts/chassis we stress-relieve joints before taking them off the jigs (oxy-acetylene to 1000 F), but that process does not give you any strength. Its just to prevent warping. You need a controlled heat-treat oven to get more strength (not that you need it with 4130). And I'm pretty sure that all steels have the problem of warping when you weld.

Quoting:
The major problem with 4130 is that all the welds need heat treating to stress relive them. If you do not select the correct weldment filler and use a high nickel stainless filler it does not like being heat treated. There is no doubt it is good stuff, we used 4130 for our space frame last year and it was excellent to weld up but you need the heat treatment to fully utilise the materials properties add this on to the already expensive cost of the material means you are left with a vary expensive chassis..

[CAV]

just to add: normalized 4130 is good for 90 ksi, not too shabby.

[Ben Beacock]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Didier Beaudoin:
I beleive Ben was talking about the cost you have to write down in the cost report. No one gets 4130 at that price. It cost us over 400$ this year for our tubing, and it was a good price already! http://fsae.com/groupee_common/emoticons/icon_biggrin.gif <HR></BLOCKQUOTE>

Exactly.. i think we were up around CAN$600. I haven't looked at the invoices yet.

The chassis and the engine seem to be two areas where spending alot of money doesn't show up in the cost report.

And to continue the actual thread topic, we have bent front and main hoops and we are now starting chassis fabrication.

[DanO]

What helps the most is to shot peen the welds for the 4130.

[Lash]

I'm confused. I thought you had to put what the actual cost of the tubing is in the cost report. Not what you originally paid for it??? Please explain.

[Chase]

materials have a set price put on them in some measure of quantity. like per pound. you have to cost out the welds and I think the heat treating but, to make it easy they give you a base price for each. So usually things like chassis don't wind up being as much as you payed to really produce them. Read in the rules about the cost report and I'm sure it is all explained.

[Lash]

Is it a must to use DOM on the chassis? Most articles I read are saying DOM is stronger and more suitable for a space frame chassis. Is DOM a must or could I use 1020 or 1026 steel ? Thanks for the help guys.

[Lash]

Believe it or not. In 2002 are team did some research on 4130 and 1020. Here are the results. I think PWHT wasn't needed because of the thickness of the tube. I'm going to try to do more research this year again to confirm this. Comments ??

Type Condition UTS (ksi) Failure
4130 Base 121 base metal
4130 welded 113.9 base metal
4130 PWHT 110.36 weld
1020 Base 89 base metal
1020 welded 75.06 weld

[Lash]

sorry the table of the results didn't look like that orginally !! http://fsae.com/groupee_common/emoticons/icon_eek.gif

[Jared Garvey]

We got our chassis on the ground tonight:
http://www.engr.pitt.edu/fsae/images/2005/IMG_0375.jpg


Jared Garvey
University of Pittsburgh
Suspension Lead
http://www.engr.pitt.edu/fsae/

[Denny Trimble]

Impressive to have a rolling chassis at this date! Don't forget to triangulate the foot box (judges safety concern).

[James Waltman]

Jared,
Is that some Nomex/Aramid/Phenolic core? How are you planning on attaching it? Have you used it like this before?

Sweet shocks.

[Lash]

Jared,

What type of steel is that made from? Looks pretty good guys. Ahead of the game !!

[D DeJohn]

James - It is Nomex core... we've used carbon fiber-nomex panels in our space frames for four years. This year, the nomex will be bonded to the tubes (probably with left over Aeropoxy 6209 or 6279), then the carbon laid up wet over the nomex and vacuum bagged. Depending on bond quality and method, we've seen 3-4x increases in rigidity compared to the bare space frame.

Lash - the crash structure is 1018 mild steel and the highly stessed areas around the suspension/shock/bellcrank mounts are 4130 chromoly, with the appropriate filler used where the two meet. This takes advantage of the mild steel's improved toughness/elongation properties while allowing thin-wall tubing where the rules don't mandate a thickness.

The shocks might not be pretty, but they're definately more consistent than a certain brand that starts with an "R" and ends with "isse."

---
Dave DeJohn
Captain
University of Pittsburgh

[jdstuff]

Kudos Dave and Jared...I didn't realize that you guys were that far along. We're pretty much finished fitting tubes, and are beginning to work on suspension tabs....goal is to have it sent out for powedercoat at the end of the month.

What are you guys planning on running for shocks this year?

[Jared Garvey]

We are going to run hunter shocks. They're made for quarter midgets. The web site is http://www.huntershocks.com They are not adjustable, but I don't think the adjustability has helped us much in the past.

Dave wants to have have a running engine by December and we want to powdercoat over Christmas break. Overall goal is a running car by February 1. Looks like the drivetrain will probably be the major hurdle.

Jared Garvey
University of Pittsburgh
Suspension Lead
http://www.engr.pitt.edu/fsae/

[Lash]

Jared How do you get your engine out ?? Do the Front roll hoop braces bolt off? HOw much does she weigh with out the engine, wheels and Control arms ??? Are previous years is about 78lbs but we hope to reduce that by 5 - 8 lbs. We'll see what happens.

[Jared Garvey]

The engine will come out without removing any of the roll hoop bracing. We have not weighed the chassis yet, but it only has a few changes over last year's. It should be somewhere around 55 pounds.

Jared Garvey
University of Pittsburgh
Suspension Lead
http://www.engr.pitt.edu/fsae/

[BA]

Started Fabrication 9-26. Finished 11-1. We still have tabs and engine mounts to attach, but we're waiting for tab stock.

http://www.webpages.uidaho.edu/~racing/Frame_Build_sm.gif

It's not on wheels, but hopefully by Thanksgiving.

[fsae racer]

Not to rain on everyone's parade, but we started shake down testing October 15th. We had some hickups with wiring the new 600rr motors we picked up at the end of last year (thanks for all the help halfast), but all of the driving has gone off without a hitch. Serious chassis dynoing plans for the next couple of months. Construction of the frame actually started June 19th and 95% of it was done by July 4th. We were trying to have a brand new car for Australia, but I guess now we will have all the opotunity in the world to work out the bugs (like last year's cooling issue). It will inevitably see some suspension revisions and hopefully drivetrain revisions as well, but check some of the pics.

http://www.gatormotorsports.com/gms/formula/2005/index2005.html

...and we had how many hurricanes almost blow our shop away. Just goes to show the unbelievable amount of support and dedication my teammates have putforth these past five months. Thanks guys. See ya all in Detroit.

[Wilso]

"Construction of the frame actually started June 19th"

June 19th!? I was still catching up on sleep from the week in Detroit. UT Austin began work at the beginning of the fall semester and we finished the frame as of the end of October. Right now we are building jigs and attaching suspension tabs and hope to remove the frame from its jig this weekend. As one of the captains, I'm really proud of the returning members, fellow captains and newbies for the way this year is starting.

[Lash]

Hey guys,

Could anyone list their suppliers for 4130. I would like to get 1"OD with wall as thin as 0.035 - 0.028

[DanO]

4130 suppliers
http://www.wicksaircraft.com/catalog/product_cat.php/subid=1827/index.html

http://www.chassisshop.com

[Denny Trimble]

http://www.emjmetals.com

[Lash]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Ben Beacock:
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Didier Beaudoin:
I beleive Ben was talking about the cost you have to write down in the cost report. No one gets 4130 at that price. It cost us over 400$ this year for our tubing, and it was a good price already! http://fsae.com/groupee_common/emoticons/icon_biggrin.gif <HR></BLOCKQUOTE>

Exactly.. i think we were up around CAN$600. I haven't looked at the invoices yet.

The chassis and the engine seem to be two areas where spending alot of money doesn't show up in the cost report.

And to continue the actual thread topic, we have bent front and main hoops and we are now starting chassis fabrication. <HR></BLOCKQUOTE>



BEN, I'm on the U of Windsor Chassis team. Where did you guys get your 4130 ? Please email me your supplier. lash1@uwindsor.ca

Thanks for any help

[ReadySetGo]

emj is who we go through. We should be ordering tubing this week. Some of you guys are way ahead of the game!

[IsheeM]

What method are you guys using to fixture up your chassis for welding? Pictures of the fixtures would be nice too.

Thanks,

[Lash]

Chassis Designers:

Is there any reason that you can give me why you sometimes see the rear box, front bulk head and bottom of the car out of square tubing. I have found that steel tubing to be very expensive and it weights 27% more. There is probably a good reason but I just can't figure it out. Any help would be great guys.

Thanks

[Didier Beaudoin]

Square tubing at this places allow for a better positionning of the suspension points. It is also handy when you use an adjustable pedal box as you can make it fit nicely. Also, square tubing is better in flexion than round tubign, so it might be a reason too.

[Lash]

I have found a company that offers 1020 DOM with strenths quite comparable to 4130 UTS 80 ksi and yield 70 ksi). EMJ also offers 1020 in tube sizes of 0.028 and 0.035. Any objections, comments, or suggestions on why I should choose either? http://fsae.com/groupee_common/emoticons/icon_confused.gif

EMJ Metals
http://www.emjmetals.com/emjonlinenew/esl.exe

Thanks a lot guys you've all been a lot of help so far!!

[JadgPzIV]

About the 1020 DOM:

Don't forget that at welding 1020 DOM will loose his properties due to cold working. Tensil strengh in the HAZ of 1020 is not very high... 220 MPa ( 4130N = 480 MPa ).

We received a report about 4130N properties after TIG welding with ER70-S2. The hardness of 1" OD 0.065" WT in the HAZ will 80% of the 'normalized' hardness.

For us, availability and good properties in 'as weld' condition are the strengh point of 4130N.

Guillaume Boucher
Ex-ULaval FSAE frame designer

[rjwoods77]

I always heard that bitch about HAZ on 1020. But in reality, with many tubes forming nodes as in my chassis, isnt that a moot point due to the amount of metal in that joint. I wonder if the stress applied to the HAZ is overshadowed by the total metal in the joint.

[JadgPzIV]

The HAZ is not at the weld but in the area in upstream of the weld. So, you cannot say that the amount of metal will compensate for the lower tensil strengh. I don't remember the typical width of the HAZ, i will look in our report tomorrow. But, if you consider that the node act as an perfect embed for the tube, the stress in this tube will be at is maximum in the HAZ in bending.

For exemple, a sidepod node, will not need 4130, I think. But for the suspension brackets tube or on highly stress member, I think 4130 is a good investment.

In 2002, our frame was in 1020 from different state (hot-rolled and cold-rolled). It weight 85 lbs, and we had a welding faillure on the bellcrank pivot, which was loaded in bending. I cannot tell you that the 1020 was responsible for this failure, maybe it was the designer! But 4130 could offer a better security in this case.

Guillaume Boucher
Ex-ULaval FSAE frame designer

[rjwoods77]

I would like to see this report if you wouldnt mind. I assume it also depends on the welder and his heat control. I know that the "rainbows" in the metal arent all the story but they are a good indicator. If done right you would want this to be as long as i can get which should indicate a decent heat spread over a joint. I think that is right. Anyway I would like to see that report if I could.

[Lash]

Did anyone go to EMJ metals site what i was saying before? They have 1020 DOM at like 500 + MPA UTS or 80 ksi. If you weld this with a ER80S-D2 rod you will keep the weld joint up to 80 kis strength... ER - Electrode Rod 80- 80 000 psi
S- solid meaning the weld metal is still able to put out 80 ksi strength. Why use a ER70S-2 for 4130 at least ? Any who...check out that site and let me know what you think. Also is there any other benefits of using steel tubing ? I did some moments of inertia calculations and found that square tubing (Same OD and wall thickness) to be 69 % more stiff (in^4) but weighs 33% more. Comments?? How is tube metal confirmed. I mean how does a judge know if you are using 1020 DOM or 4130 ? A 1020 DOM chassis would score a better score in the cost report. But 4130 might be better for design.

[JadgPzIV]

<span class="ev_code_RED">Lash - They have 1020 DOM at like 500 + MPA UTS or 80 ksi. If you weld this with a ER80S-D2 rod you will keep the weld joint up to 80 kis strength... ER - Electrode Rod 80- 80 000 psi</span>

False, the joint (metal filler) will be around 80 ksi. The tubing outside the HAZ will be at 80 ksi. But in the HAZ, where the temperature had reach over 728?c, all the properties due to cold working (because DOM means 'drawn over mandrel') will be 'erased'. So, in the HAZ the 1020 DOM will have a ultimate strengh nearly as low as an hot rolled 1020, 40 ksi.

Maybe 40 ksi is largely enough for a tubular space frame, but don't buy 1020 DOM for is high utlimate strengh if you weld it.

Guillaume Boucher

[JadgPzIV]

Lash - <span class="ev_code_RED">Why use a ER70S-2 for 4130 at least ?</span>

Our welders prefer to weld with ER70S-2 and ER70S-2 have a better ductility than ER80S-D2. In our hardness analysis, weld with ER70S-2 had an hardness higher than base metal (4130N). So why use ER80S-D2 ?

Lash - <span class="ev_code_RED">I did some moments of inertia calculations and found that square tubing (Same OD and wall thickness) to be 69 % more stiff (in^4) but weighs 33% more. Comments??</span>

When I designed our 2004 frame, I made the same calculations. I really like the "33% difference in weight". I use round tubing for all the frame except 4 members. I reach easily my stiffness goals, but the frame was very hard the built and we loose a lot of time for reaching a good precision. This year the guys will use more square tubing according to my experience. Fabricability is very important for a frame. It's my little experience!

Lash - <span class="ev_code_RED">How is tube metal confirmed. I mean how does a judge know if you are using 1020 DOM or 4130 ?</span>

They will never know!

[Lash]

JadgPzIV, you're absolutely correct about the HAZ, I forgot to take that into consideration. We have a welding course that is offered as a technical elective here. Really good course. We learned all about martensite formation in the HAZ, affecting ductility and strength. We are doing FEA today and hope to get some max yeilding stresses to finalize what type of metal were going to use. Thanks for the help!! http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Lash]

What is a worst case senario for doing FEA? We put a coupled moment with 500 lbs on each side of the chassis through the control arms. We are going to also do a worst case senario with lateral forces in the skid pad. What kind of senario's does your team design for? Stiffness values ? Last year our car was 1800 ft.lbs/deg and 77 lbs weight.

[Greg H]

http://www.kengrimes.com/newframe.jpg
Here I am giving it a test drive. VROOM VROOM!