Upright weight

[Conor]

I'm designing new rear uprights and am trying to shave as much weight as possible. Anybody got any weights for their uprights so I have a window to shoot for? Like always, any information is very appreciated.

[mario_rbr]

4130 sheet metal
Weight: 1,1275 Kg. = 2,5 lbs
and We are a rookie team...

[CMURacing - Prometheus]

i think 2lbs is the gold standard, but ask penn state how much theirs weigh...

[billywight]

Ours are 1.8lbs not including hardware.

[Jersey Tom]

Somethin around 2 lbs I think. I'll weigh em in a couple days. Saving a half pound each from last year, which is primarily in the wheel bearing. Really hope they work! haha

[adrial]

1.6lbs for the upright body (designed for integrated taylor CV's) w/integral toe link bracket

[KU_Racing]

1.0 lbs front, .95 lbs rear, before toe brackets and bolts

[Mike Cook]

1.6lb fronts with out bolts.

http://www.kodakgallery.com/BrowsePhotos.jsp?Upost_sign...&collid=174555007106 (http://www.kodakgallery.com/BrowsePhotos.jsp?Upost_signin=&UV=650326070939_617355007106&collid=174555007106)

[Storbeck]

Are all of these weights including hardware, bearings, bolts, etc...?

[Marshall Grice]

1.6lbs front, no bolts, bearings, hub/spindle, or caliper.

[Jersey Tom]

The bolts and bearings are just as important, guys. Add em in.

[Dave M]

it doesnt seem like anyone is that far yet..... we arent

[Mike Cook]

But Come on, that is not nearly as impressive http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

[Matador Motorsports]

Front: 1.24 [lb]
Rear: 1.11 [lb]

[adrial]

Bearings are 0.2lbs a piece... so 2lbs for the rear upright I listed with bearings.

Another ~1.6lbs for the hub with integrated CV housing

Fronts were similar, 2lbs upright w/bearings, 1.6lbs hub w/rotor mount (live spindle)

Bolts not included...so add a little bit http://fsae.com/groupee_common/emoticons/icon_wink.gif

I look forward to seeing some of these uprights at competition...numbers are pretty impressive, but tough to compare because you dont know what needs to be added before it can be useable on the car.

Those are last years (first gen of billet aluminum)...this year got lighter. http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

[Jersey Tom]

.2 lbs??? Wow. That's a small bearing. I was happy going from the 1 lb Taylor bearings to .5 lb INA ones.

[KU_Racing]

got weights for our uprights to satisfy the whole 'include everything' mantra.d

1.58 lbs front, including spindles/toe brackets/bolts/bearings/camber shims

1.7 lbs rear, with bearings/toe brackets/bolts/camber shims

[Mike T.]

Ours are around 2.5 lbs. You may want to consider more than just strength and minimum weight in your design though. It's not very difficult to design a 1 lb upright that won't fail, but chances are if its so light camber and toe deflections of the suspension under load will be much more that the kinematic changes designed into your geometry, and you'll end up with unhappy tires that could be doing a lot more work for your car. It's a matter of your teams apprach, and which factors you consider to have a greater effect on the performance of your car, but something to consider.

Mike Trumbore
University of Washington '03-'06

[Garlic]

Cue the above teams with super light uprights posting how ultra mega stiff they are (with no numbers or data of course) http://fsae.com/groupee_common/emoticons/icon_wink.gif

[LSU Dave]

Our fronts are a bit portly with everything attached at just under 4 pounds. Rears are approximately the same with the Taylor upright bearing pressed in. Solid 4340 spindles in the front, 6061 Al shafts running in the back.

Better safe than sorry for the first year... decided to go with a thicker wall thickness and higher factor of safety.

[Conor]

I got ours down to about 2.1 pounds with no bearings, bolts, etc... I FEA'd the shit out of them and they seem as if they'll be ok. We're also a first year team so I don't want to risk too much, but with everybody else's uprights so light.. I think we'll be ok. But this still seems pretty heavy by comparison.

[Marshall Grice]

Cue the above teams with super light uprights posting how ultra mega stiff they are (with no numbers or data of course)
...but isn't that what online bench racing is all about?

[Nitesh]

We have our front ones at 2.2lbs with 6063T6. what alloys do you people use and what FOS do you aim for as i see some pretty impressive numbers there (<2lbs esp <1.5)

[Mike Cook]

Originally posted by Garlic:
Cue the above teams with super light uprights posting how ultra mega stiff they are (with no numbers or data of course) http://fsae.com/groupee_common/emoticons/icon_wink.gif

Right on...After doing a lot of analysis on our unsprung components we increased stiffness by about 5 times with only a slight increase in weight. Spindle stiffness was a big problem. What are you guys shooting for as far as deflection goes? I think our total deflection (spindle, hub, upright, a arm) is about .25-.5 degree. I wish we could reduce this number but things start to get heavy. Anyways this is a big improvement over our 05' car. Up until a point I think stiffness is more important than outboard weight.

Also, I'm not a huge believer in fea. Especially at this level. Even hand calculations only get you so far on a lot of these things. Physical testing is important I think which is something we have yet to do. Also I'm not concerned with saftey factors. With everything outboard our saftey factors are very high because of the need for high stiffness. Well this goes for things in bending. Tension/compression members can be much less weight and less stiff because for the most part there not a very high percentage of the overall deflection. Anyways, it has been a long night at the lab and I'm going to sleep now. Tough though, getting anxious for racing season to start back up.

[Conor]

I'm going to agree with the whole FEA thing. I ran some pretty basic ones on our uprights in Pro Mechanica to get an idea. I just constrained our linkage points and put the maximum braking force acting in the opposite direction of the car going forward at the center of the bearing journal of the upright. I know this probably isn't the best way, but I wasn't looking to be that exact. How did everybody else do theirs?

[Jersey Tom]

FEA..

Constrained the suspension pickup points to the appropriate degrees of freedom. Applied a remote load through the bearing housing from the contact patch of the tire with the appropriate forces. Bada bing.

Coulda pulled a good amount of weight out of them if they a) weren't universal [though I like that better] and b) our 7068 had come through rather than 7075. Still a good design, if I say so myself. Think the bearing housing only deflects .2 degrees under full loading, something like that.

Definately gonna tweak em for next year. Very much convinced I can still make em nearly as light, still, and strong as a welded steel box design. Much more homogenous material. And manufacture them faster, especially running a 3/4" endmill through em at 80ipm.. or 2" facemills at 65. Fun fun fun.

[Mike Cook]

Can't find much on 7068 even in the mil handbook. Found on the net its yield is 98ksi and ultimate is 102ksi. Pricing? Downsides?

Also Tom, we did the same thing as you with regard to FEA but it was much more difficult to get it to work with a boxed steel upright as opposed to a single CNC piece.

[Jersey Tom]

Yea, 7068 is strong stuff. In the T6 condition, yield of 93ksi and UTS of 103ksi is about right (I don't have the data sheets in front of me this instant). Was originally developed in the mid 90s as an ordinance grade alloy for use in assorted weapons systems. From memory it has pretty similar fatigue and fracture toughness properties as 7075. Its only recently started to spread into the public domain.

I don't know what it prices at retail, we were going to have a fair amount donated to us by a sponsor, but for one reason or another that didn't happen and instead we got 60 lbs of 7075, which still has worked great. But hey according to the cost report all aluminum is $.75/lb .. http://fsae.com/groupee_common/emoticons/icon_rolleyes.gif

Dig around, there's a couple places that sell 7068. Might not be super available.

Another real nice alloy to look into for billet designs is 7475. Strength of 7075 with much improved fatigue and fracture properties. Or if you were to make something out of welded sheet that needed to be very structural, 2090.

[Chris Allbee]

One thing about FEA. As long as you have realistic boundary conditions (good assumptions), then your stiffness (not deflection) should be fairly accurate (often within 2%). The reason I say stiffness is that your loading will be a function of so many other variables that when discussing it with someone else it is nearly worthless to say "deflection of .2 degrees under full loading". Your car is different than my car is different from the next car. A number of say... 1.3 deg/g for example is much more enlightening because such targets can be adapted to other vehicles. As far as stress with FEA...don't bother unless you have done correlation testing with your meshing techniques and the proven results of the part. Just get it close and make sure you have a comfortable safety factor. Besides, with uprights once you have the desired stiffness and have removed any sharp corners the stresses usually are much lower than your yield strength (and often fatigue limit) of the material.

[Marshall Grice]

as a side note, .2deg of deflection is ~ .125" of toe change. Doesn't seem incredibly stiff to me, but then again i haven't put forth any numbers so take my comments as such.

[Jersey Tom]

My bad, I was off by an order of magnitude. Camber and toe changes are under .03 degrees.

http://ucsu.colorado.edu/~szelag/uprights.JPG

http://ucsu.colorado.edu/~szelag/rears.JPG

They'll be lighter for next year.

[kwancho]

How are you attaching the 2 ball joint part to the rest of the upright? And you're using the same for front and rear?

[Jersey Tom]

Dowel pin to transmit shear, bolt + nut for pull-out.

Same basic part front/rear, left/right. Only difference are the locations of like 4 holes.

Workin on the '07 uprights right now. They'll be mo betta.

[Ryan Colton]

So, in the past our upright design has had a large focus on how light we can make it and not how stiff. Currently our front uprights are as follows.

Aluminum 7075-T6
Weight 1.3lb 38,000 in-lb/deg camber
Steel 4130
Weight 1.5lb 62,000 in-lb/deg camber

Another team I talked with
Steel 4130
Weight 2.5lb 96,000 in-lb/deg camber

I did not have my toe stiffness numbers with me or else I would have put those with this.

I guess the question is what weight/stiffness do you want?

On our car with a 670lb total weight, 10.5" CG, 50in track, 20in tires, 1.66in spindle length, 50/50 distribution, and 1.5g corner. I came up with a 3,642 in-lb moment on the upright.

Assumptions for the calc; the kingpin axis intersects the spindle axis (which it does not on our car), only account for the moment about the longitudinal axis of the car, and zero static camber.

Respectively this is

3,642/38,000 = .096 degrees loss

3,642/62,000 = .059 degrees loss

3,642/96,000 = .038 degrees loss

Just wanted to put these numbers out there to see what other people are getting and if I am in the ball park? Also what is a good number to shoot for?

Ryan Colton

[KU_Racing]

Hey guys- I dont have the time to add all the specs of my car like Ryan did, but here are the FEA stiffness number for our current uprights and the current version of the 07's:

2006 uprights:
welded box structure, Titanium grade 6AL-4V
stiffness across toe base: ~112,000 inch lbs/degree
weight: approx 1.4 lbs w/ bearings and hardware

newly designed uprights, V 1.4
solid 7475, CNC machined, 7075 toe brackets
stiffness across toe base: ~60,000 inlb/deg
weight: 1.95 lbs including bearings and hardware

[Jersey Tom]

Have you already locked down on a supplier for 7475? Few months ago when I was lookin into all this it was hard to even find a good amount of 7075 or 2024.. much less 7475, 2124, 7068..

With regard to stiffness, you gotta figure how stiff is stiff enough. Don't overkill if you don't need to.

Welded 6-4 uprights.. that's sweet. Ti welds done right look killer. You guys use GTAW or EBW? How consistent did the weld strength come out to be? How does the fatigue life of welded Ti compare to the base metal? Steel weldments are often on the order of 70% or less I believe. (Our faculty advisor did some analysis of premature fatigue failure in welded suspension components in city busses back in the day)

Since Ti welds are so damn finnicky and can easily form microcracks at the surface of the weld.. have you thought about the propagation of those microcracks down deep into the weld and substrate material?

[Mike Cook]

All those numbers sound good with respect to deflection. However, some validation is definitly needed. I think if you can get wheel deflection down to about .25 degrees of camber at full lateral acceleration you are in good shape. Our team was right around .35 degree of camber but this didn't include the actually wheel deflection. I imagine Keizer wheels deflect a lot.....food for thought definitly. I think that most peoples total wheel deflection is a lot more than they think.

[Ryan Colton]

Mike,

My next question then would be where did the .25 degree camber loss number come from?

Question for everyone, has anyone done some sort of analysis to help determine what is stiff enough such as the analysis Cornell did for their chassis stiffness, if people have seen that?

Ryan Colton

[Mike Cook]

Ryan, if i'm understanding you right your asking where does deflection come from: hubs, spindles, uprights, a arms, and wheels.

Anyways, I was thinking about your second question and I can think of two responses. 1) the more deflection you have while cornering, the more negative camber you will need to run to compensate, which will affect you negatively under pitch conditions (braking, accelerating). Also, depending on your scrub radius, stiffness is important so that you don't have toe changes under braking and accelerating.

I think that toe changes are more detrimental than camber changes. When trail braking into a corner or whatever, I think the toe changes would affect you most.

Mike

[Conor]

Jersey Tom,

I saw your photos. Sweet uprights, nice machining work. But there's something I'm really concerned about. WHAT THE HELL WERE YOU EATING??? I looked at that for awhile and I can't figure it out. Can you shed some light on how you constructed that meal? What was your ingredient choice and why? Also, was an analysis and FEA involved? Thanks!

[kwancho]

That pasta needs more stiffness. Shoulda cooked it less.

[Ryan Colton]

Mike,

Sorry I must have stated my question wrong. What I meant to ask was how you came up with .25 degrees of camber as a design goal.

I understand your points that you gave and I agree though I was hoping to come up with a way to quantify the stiffness versus weight compromise of the camber and toe, any ideas?

Ryan Colton

[Jersey Tom]

Dude.. one of our team captains hooked up the pasta. With this crazy marinara-ish sauce. One of those all-night machining deals.. just crankin out toolpaths, lettin the spindle spool up to 7 grand and make some aluminum billet your bitch. Hadn't eaten all day. Was some friggin good pasta. I'm afraid I cant divulge the microstructure of the sauce. Would give an unfair advantage to you guys. Buy us some drinks at competition, or beat us in arm wrestling, and maybe we'll let some secrets slip. Whatever, I just got back from the bars, time to sleep.

[B Hise]

just crankin out toolpaths, lettin the spindle spool up to 7 grand and make some aluminum billet your bitch.

when FSAEers drink...

[Mike Cook]

Ryan, I would think that toe deflection should be like less than half of your total static toe setting. This is difficult to accomplish when you start looking at deflection in your toe rod (and if you have a small distance between your toe rod and your ball joint) and the deflection of your spindle, and upright. A lot of this can be helped if your scrub radius is minimized.

For camber, I would use tire data to look longitudinal forces vs camber. Look at how much force you loose due to camber deflection and make some sort of compromise.

Overall, toe is probably a much more important factor in stability than a 1/3 of a degree of camber...

[Ryan Colton]

Mike,

I decided to run some test on our 05' car and found that our outboard is somewhere around .2 degrees/g. I was not able to measure at the edge of the wheel because there was not a good surface to measure from so I had to measure at the wheel center bolt pattern. Also my data had about a 20% error plus/minus. I am going to go ahead and rerun the test and see if I can't improve the results, just thought I would share what I found.

Ryan Colton

[KU_Racing]

Hey tom- sorry this took me so long.
The uprights are assembled from machined/water jetted components and then TIG welded in house in a chamber that I built for that purpose. The strength of the welds is pretty good, with fatigue strength about 90% of the base metal on average.

You are right, there is a real danger of deep microcrack propagation in the Ti welds. The trick to avoiding the cracking is doing ridiculously insane amounts of prep work, and making dead sure you have the right filler rod. It takes so much prep work, in fact, that we probably wont use Ti after this year- on a team as small as ours, it just takes too much time. Last year we had a failure and we cranked out 2 4130 front uprights in about 3 hours- i have about 10 hours of work into the 06 uprights, and they are not even halfway done yet. Before we weld any Ti, everything is wire brushed, then cleaned with soap and water, then inspected for pitting (stainless bristle shavings in Ti weld puddle = death to test driver) then cleaned with acetone to remove oil and soap, then cleaned with MEK to remove acetone. Kinda nuts really. then the chamber has to be purged, then ONE bead is laid, then the chamber is purged, etc etc etc. You can overcome a very very slightly contaminated puddle with the right filler, but I say better safe than sorry. One nice thing about the welds is, not only do they look ultra mega sexy, but the material doesnt harden the same way that steel does, so the weld maintains most of the ductility of the base metal.

we do have a supplier who can get us 7475.... we still have to pay for it though, which is the nasty part.

As far as stiffness goes, Id say that there is no such thing as too stiff if you can do it with the same or less weight- hence the Ti uprights. I have some pics that I would show you guys of our various test samples, but I dont know how to post pics on this forum http://fsae.com/groupee_common/emoticons/icon_cool.gif

update: couldnt figure out how to post pics in this thread, so i created a new one under general discussion for anybody who wants to see the test pieces.

Jimmy

[Marshall Grice]

where are the pics of the actual uprights?

[Conor]

Jimmy-

Can you post some pictures of the uprights once they're finished? You say they look "ultra mega sexy" when finished, but by reading everything you go through for them, I'm doubting that the way they look is worth the effort. I'm sure everyone else reading this thread would love to see them as well. However, I will say bravo for your originality and persistence.

[Jersey Tom]

Sweet Jimmy. Good to see you're doin it right. If you guys are goin to east I'll have to check them out.

[Storbeck]

Are your stub axles titanium also? What alloy are you using?

Why titanium?

Seems like the density and modulus of elasticity of most titanium alloys are both about half of steel. Since we've already established that the design of uprights is limited by stiffness, not strength, I don't see any advantage. The manufacturing methods sound like they are the same either way, cut and welded sheet, why not just use steel sheet that's half as thick and way cheaper with less hassle?

[KU_Racing]

The uprights are grade 6AL-4V (grade 5), the strongest 'weldable' grade available to us. Storbeck, look up grade 5- it is some ridiculous stuff. Check earlier in this post for our stiffness and weight numbers- the stiffness to weight of a properly welded Ti upright is well above any machined or welded aluminum or steel.

As far as how the uprights look, the look good- but that is a side benefit of the properties of the material. We arent using the Ti because it looks good- we are using it because it is a better material choice. If it happens to look bling-blong as well, I say why not.

Also, we have a supplier that gets us Ti for uprights and spindles very very cheap- our spindles were free (the material- we still machined them). The sheet costs about 20 cents more per square foot than 4130 of the same thickness, so cost isnt really a factor. The only thing that sucks is filler rod- filler costs like $45 per pound... the good thing is that the Ti is insanely light, so a pound of filler is enough for all of the uprights and control arms, with about a quarter pound left over.

I think I have said this a bunch of times in previous threads- despite the attitude of my posts on this thread, I don't like using the titanium. I think that if the footwork was done, an upright could be designed with similar stiffness numbers, at a very slight weight penalty. The weight penalty, however, would be offset by significantly greater ease of manufacture. I am not the team leader- I am the fabricator- so it isnt my decision what materials we use. The team leader tells me what material parts are going to be made of, and then it is my job to make it happen. When I am team leader, and it is pretty likely that will happen next year, We will most likely be moving to a CNC aluminum or sheet chromo design.

For those of you that asked about pictures, I will post them as soon as the uprights are done- hopefully this weekend if there are no surprises.

[TG]

Originally posted by KURacing:
The uprights are grade 6AL-4V (grade 5), the strongest 'weldable' grade available to us. Storbeck, look up grade 5- it is some ridiculous stuff. Check earlier in this post for our stiffness and weight numbers- the stiffness to weight of a properly welded Ti upright is well above any machined or welded aluminum or steel.

If you are looking at the properties of materials in tension, yes, titanium comes out ahead being normalized by density. However, looking at bending and buckling, high performance aluminum and magnesium alloys trump Ti 6-4, density normalized. The calculations are very simple, just take

(density1/density2)*(modulus2/modulus1) which gives you the weight ratio in tension (<1 = material1 is better, >1 = material2 is better)

(density1/density2)*squareroot(modulus2/modulus1) which gives you the weight ratio in bending (<1 = material1 is better, >1 = material2 is better)

(density1/density2)*cuberoot(modulus2/modulus1) which gives you the weight ratio in buckling (<1 = material1 is better, >1 = material2 is better)

You can see the density starts to prevail for the normalized calculations of bending and especially buckling. So unless you've magically set up your uprights in pure tension and compression (a whole bunch of stringers???) it could be a better choice to go with a less dense alloy.

[TG]

I forgot to mention the above equations are only valid for isotropic materials. Anisotropric and orthotropic materials (like composites and cast metals with directional microstructure) can't be solely looked at with these, but they can be refered to.

[Storbeck]

KURacing, I did look up the properties, it is almost exactly half as dense and half as stiff as steel. It also has a really high yield and ultimate strength. Which is great for keeping a wheel from falling off, but doesn't really help much with stiffness to weight ratio. That's why I was wondering what the advantage of the ti is.

TG interesting, I came to the opposite conclusions but with much simpler logic, never really sat down and crunched numbers about it though so maybe my logic is flawed, but here's how I look at it.

You have two materials that we will call steel and titanium, steel is twice as dense and twice as stiff.

Say you have a rod in tension, it's fairly easy to see that if the modulus of elasticity of ti is half of steel, you need twice the cross sectional area to get the same stiffness. Becasue of this you will have twice the volume, so the thing will have the same weight and stiffness.

Now take a beam in bending the dimensions of the beam are b and h so that the moment of inertia is 1/12bh^3, to get the same volume you can either double b or double h on the ti beam. If you double b, the moment of inertia is twice as high, so the stiffness to weight ratio is the same. If you double h, the moment of inertia is more than twice as big, so with the same weight, you greater stiffness. This of cource is limited by space, because if you have the space for it you could have just made the original steel beam with double the h, though eventually you hit the point where it is not practicle to make the b number any smaller, so less dense material has an edge. By this logic the lower the density, the better for stiffness to weight ratio of a bending beam as long as you have room for it, and the modulus to density ratio stays roughly constant, which it usually does. Based on this I would choose aluminum or even magnesium as the best choice of material for machined uprights which are basically designed as solid beams in bending.

However, with a fabricated sheet upright, It's a little different. Since the cross section is that of a hollow box basically, the moment of inertia is not significantly affected by the thickness of the material. Say you have a fabricated sheet upright that is roughly a 2" by 2" box, fabricated from .035" thick steel sheet. To get the equivalent stiffness from ti it seems like you'd just take ti sheet that is .070" inches thick, and you'd have basically the exact same stiffness to weight ratio.

my $.02 sorry for the long post

[Storbeck]

Just realized that what I said actually pretty much agrees with what TG says.

[Conor]

I really wouldn't keep ripping into KU. He already admitted, that if done his way, the uprights would be made from something more practical like a machined aluminum. The fact that he gets the titanium so cheap and actually has the means of making a welded titanium upright is awesome. Give the guy some credit for creativity.

[KU_Racing]

Thanks Conor for actually reading my post.

I really dont have much else to say on the subject- I didnt plan on defending the material choice that the team made, and I dont care to do so, especially since it is already clear that I would do something else if it was left up to me.

I will hopefully have some pics soon. I just got into the shop today, and found out that there is not enough argon to finish the Ti welding, so no pics this week. Maybe next week!

[Andrew Nabb]

I figured it was time I chime in and help out, since it was my choice to use the Ti.

I think everyone here has rushed into a one dimentional look at the uprights. Yes the parts are primarily build with stiffness targets in mind, however it is not as simple as just the stiffness to weight ratio.

Assume we use steel, which we infact did in 2004. It is obviously a lot easier since you can use boxed chromo tubing and have the part done in a matter of an hour or two. However it is not as simple as just using "half the material". The titanium uprights are a weldment made from .059 and .061 sheet titanium. This would force you to use .028 thick sheet to get half the material if the same design was used. Anybody out there feel brave? To put it lightly, it would be a "challenge" to weld .028 to a bearing cup or spindle due to the thickness differences. Plus what do you think will happen when the part is droppped, hit or dinged?

Another consideration is the spindle or bearing cups. Those parts are usually feature depended and are not as simple as the "material vs stiffness" rational. Yes the wall thickness is probally set to a minimum based on stiffness, but there is almost always material left for bearing thrust surfaces and other features. A large portion of our weight savings came from the bearing cup and spindle "dead weight" spots that now just weigh half as much.

Everyone also compares their numbers of umpteen million lbs per degree of stiffness, but what about other camber and toe losses? Anyone have tie rods and rack mounting that is umpteen million lbs per inch of deflection? How about bearing packages? Anyone have bearings with no slob or bearing housing that have the same lack of deflection? I know this will bother people on priniciple, but do you really need the level of camber and toe control that some of you are designing for? Do you have any evidence of grip sensitivites at that level, or is it just "desktop racing" as we call it at TRD. I won't release the actual number for the trucks we have at TRD, but lets say the camber deflection in some corners is beyond measurement with tenths of a degree!! If our cars were that sloppy, i think it would be time to worry more about stiffness.

The greatest part about FSAE is the freedom to push your project in the direction you think is best. Some teams will put their emphasis on component stiffness, with the thought that the camber and toe control will be worth the additional weight. Others teams, like us, place more emphasis on vehicle weight. I remember in 04 when penn state schooled a lot of better constructed vehicles with that 410 lb 600cc monster. Last year before we broke parts in testing we had our car down to 445lbs, not bad for a cost report price around 16g.

I will buy a round at FSAE west for anyone else who can get their spindle and upright weight combined down to 1 lb.

[Conor]

That's a very tempting offer my friend. I would have to say that the push to excel in the FSAE competition no longer comes from the bragging rights, but the free beer everyone talks about... You guys might be able to own my team on the course and in the design comps all day, but we'll school you on the beer pong tables all night... CHEERS

[TG]

Originally posted by Andrew Nabb:
Assume we use steel, which we infact did in 2004. It is obviously a lot easier since you can use boxed chromo tubing and have the part done in a matter of an hour or two. However it is not as simple as just using "half the material". The titanium uprights are a weldment made from .059 and .061 sheet titanium. This would force you to use .028 thick sheet to get half the material if the same design was used. Anybody out there feel brave? To put it lightly, it would be a "challenge" to weld .028 to a bearing cup or spindle due to the thickness differences. Plus what do you think will happen when the part is droppped, hit or dinged?

Andrew,

the equations above would support this. They suggest less dense materials over over more dense materials (like steel). You would have an even larger material section with aluminum and further more with magnesium.

[Conor]

You guys are kicking a dead horse here...

[Andrew Nabb]

Conor,

If you make it out to FSAE West you will have to stop by and hang out. Our team does not claim to be champion drinkers, however keep in mind with the dismal 18% female population we have at kettering, we have a long line of drinking history. We also have less to live for.

As for TG's comment about using Al or Mag...those are also good choices if used properly, however you lose the ability to easily weld in bearing housings and spindles.

[KU_Racing]

I agree. Conor, be careful about challenging Drew to a beer pong battle. You just might win.

As for girls, Drew, dont lead the poor guy on- 18% is a technicality- we all know that 90% of that 18% does NOT count as female.

[Conor]

I actually was enrolled to go to Kettering but withdrew at the last minute because I couldn't afford it, so I do understand your alcohol consumption tendencies. The lack of women would definetely contribute to that. However, Western, as you know has quite the reputation for partying, and with that, we take great pride in our beer pong skills. What soccer is to poor kids in third world countries, beer pong is to us. At WMU, champions are made one cup at a time... I would be delighted to challenege you guys to a few rounds, but we'll be competing in Michigan. Why did you guys decide to go all the way out west?

[KU_Racing]

decide... hmm. well we didnt exactly decide.. it was more a case of one particular reterd forgetting to register.

[Conor]

That sucks, especially because you guys won't have a chance to defend your home turf. California should be cool though...

[KU_Racing]

yeah.. well judging by what happened last year, it wasnt ours to defend. Cali should be sweet though. Last year I spent 45 hours of the 72 fixing the car.. this time, if she breaks, I will be on the beach. http://fsae.com/groupee_common/emoticons/icon_cool.gif

[CMURacing - Prometheus]

hate to burst your bubble KU, but cal speedway's at least an hour and a half from the closest beach. and i'm sure that's NOT the one where the hot girls hang out, its more like 2 to 2.5 hours.

[Charlie]

No way, if you don't hit the bad traffic (not easy, I know), Newport Beach is an easy hour away. Plenty of hot chicks in the OC. http://fsae.com/groupee_common/emoticons/icon_wink.gif

[CMURacing - Prometheus]

ok, agreed, its possible to hit the 605 to the OC. but its still the OC, and no self-respecting LA-county native (moi) would take newport over malibu, zuma, and county line.

so its still 2 hours. http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

[Erich Ohlde]

dang, 19%? that sucks. here at KU we have: Percentage of men to women: 48 to 52. And plenty of hot Chi Omega's and Tri-Delta's to go around. You guys need to come to our campus and chill on the 'beach from 11am to 1pm on a 90 degree day. Hotties galore

[Andrew Nabb]

52% female population...sure when are we invited? How do we get there? Click our heels together 3 times and say "there is no place like home?"

[Erich Ohlde]

2006 SCCA solo II nationals and SCCA National Runoffs. See ya there

[Charlie]

I think Auburn was close to 60% female... and quality too. Luckily we were dorky engineers so besides some time spent googling out of the shop bay doors, we still managed to accomplish something. http://fsae.com/groupee_common/emoticons/icon_wink.gif

[Conor]

I've got you all beat... our shop is right next to the women's dance studio and performance theatre. Trying working on the car when theres women stretching 3 feet down the hall all day...

Wait, no, I'm fantasizing again. Our shop isn't even on main campus, heck, the engineering college is even't on main campus. I see about 2 hot girls a day... YOU ALL SUCK

[KevinD]

Conor, as a hope college alumni (in holland), i can say it was a great college for the girls, but no cool race cars to build there http://fsae.com/groupee_common/emoticons/icon_frown.gif so you have the best of both worlds, being 45 minutes from a school with over 65% female (and usually pretty wealthy), and having race cars to build at your school. plus you have lake michigan beaches... holland and grand haven beaches are top knotch during the summer. having grown up on the holland beach and all.... http://fsae.com/groupee_common/emoticons/icon_wink.gif

[Conor]

Alright alright... so I'm not that unfortunate. I actually grew up closer to Grand Rapids so I'm well aware of Hollands offerings and you are very correct. I still think, however, that putting a dance studio next to the shop wouldn't be a bad idea... http://fsae.com/groupee_common/emoticons/icon_wink.gif

[KU_Racing]

Hey- anybody that goes to UTA cant complain. First, you reside in the greatest state in the union (Texas, of course) and second, you are not too far from SMU. If you like smokin hotties with more money than they know what to do with, SMU is the place to be.

[Conor]

Originally posted by Andrew Nabb:
Conor,

If you make it out to FSAE West you will have to stop by and hang out. Our team does not claim to be champion drinkers, however keep in mind with the dismal 18% female population we have at kettering, we have a long line of drinking history. We also have less to live for.

As for TG's comment about using Al or Mag...those are also good choices if used properly, however you lose the ability to easily weld in bearing housings and spindles.

Andrew,

We definetely won't be making it out West, so that's pretty much out of the question, but I'm sure the guys on the team would be game for some Kettering vs Western beer pong. Maybe we can even bring the car and get a shootout going with that too. Gotta stick together and show people that Michigan is still the holy land of automotive engineering...

[KU_Racing]

I am definately down for another michigan shootout to go with the SVSU grand prix.. maybe we should work on that.

[Conor]

Michigan Tech actually hosts an invitational every winter for their mini baja team. I was watching a video on it last night and they've have atleast 5 times I think. Something along the lines of that format would definetely be a good time.

[Adhoksh]

Can anyone suggest me a material other than aluminium which is cheaper,lighter,stronger and durable to make an upright for a car?

[JulianH]

Cheaper, Lighter, Stronger and durable...

Do you want it also to be blue?!


I think aluminium is perfect for an light upright, of course you can use titanium, but it works quiet well with aluminium.

[Will M]

cheaper,lighter,stronger and durable

Pick two of those and you might get some where.

A welded steel upright could be cheaper, stronger, durable and about the same weight.

But none of this matters if you can't design it properly.


-William

[luxsosis]

Originally posted by Adhoksh:
Can anyone suggest me a material other than aluminium which is cheaper,lighter,stronger and durable to make an upright for a car?

Beryllium.

If I assume you're buying aluminium from a seller who marks the price up lots, it could be cheaper...?

[Adambomb]

Originally posted by Will M:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">cheaper,lighter,stronger and durable

Pick two of those and you might get some where.

A welded steel upright could be cheaper, stronger, durable and about the same weight.

But none of this matters if you can't design it properly.


-William </div></BLOCKQUOTE>

After learning about shape factors in advanced machine design, one will discover that there can be an advantage to a denser material for components in bending. Also, from a manufacturing standpoint, it's easier to make parts super-lightweight with additive processes rather than subtractive. Especially for relatively complex shapes like uprights.

[Will M]

Adambomb,

Are you suggesting something like cast or RP’d steel/TI uprights?
I have seen them done well with a hollow construction and also so poorly they were basically a piece of bar stock.

I can understand choosing steel over aluminum for some constructions but I don’t see how a higher density is a benefit.
Could you link a resource?

-William

[Z]

Will,

I guess Adambomb is referring to "fabrication". Thin sheets of 4130 cut and folded, some machined 4140 gubbins, all progressively TIG welded together... This process can give you almost any level of complexity.

Also, given similar strength and stiffness per kg for the different materials, a higher density is an advantage when the part has to fit inside a restricted envelope. Essentially, the denser material has more of itself close to the maximum diameter, where it works more efficiently. Compare bending strengths/stiffnesses of a solid aluminium round bar with a steel tube of same mass and same outside diameter.

Z

[Adambomb]

Originally posted by Z:
Will,

I guess Adambomb is referring to "fabrication". Thin sheets of 4130 cut and folded, some machined 4140 gubbins, all progressively TIG welded together... This process can give you almost any level of complexity.

Also, given similar strength and stiffness per kg for the different materials, a higher density is an advantage when the part has to fit inside a restricted envelope. Essentially, the denser material has more of itself close to the maximum diameter, where it works more efficiently. Compare bending strengths/stiffnesses of a solid aluminium round bar with a steel tube of same mass and same outside diameter.

Z

Yep, exactly what I was talking about on both accounts!

[Will M]

Ok, I was also referring to fabricated or 'box' uprights.
And I see your point about denser material being beneficial in a restricted space for equal stiffness/weight materials.

-William

[Adambomb]

Here's a more detailed discussion on material shape factors. So you start out with the somewhat obvious realization that i-beams are better in bending. You go from there, and identify just how radical you can go from that geometry for a given material (turns from i-beam to h-beam). Then at some point you realize that all you're trying to do is just put as much material as you can as far away from the neutral axis as you can.

Then you realize you can get "more material" further from the axis if it's more dense...as Z mentioned, you go from a solid or nearly solid geometry to a thin-walled structure. If it's in bending, rectangular tubing with speed holes is hot stuff (and has that lovely '60s "swiss cheese" flair).

Ashby took this one step further and decided you can quantify shape factors based on loading conditions and material properties. This was discussed in detail a couple different 500-level advanced machine design and manufacturing classes at ISU, I'm guessing you will find something similar in other schools.

Material Shape Factors by Ashby (http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CDoQFjAA&url=http%3A%2F%2Fwww.materials.ox.ac.uk%2Fuploads% 2Ffile%2Fdesign%2Fdesign_notes3.ppt&ei=f2wZUYT9MqyS2AWQhoHwBQ&usg=AFQjCNG5bUkuGdC7PaGNPu9wl3TTibe8zA&sig2=WxGf-IlCZ4lJVX_YCnRY6A&bvm=bv.42080656,d.b2I&cad=rja)

[Paul Achard]

IMO it's misleading to talk about density instead of modulus when considering second moments of area (Izz). The two arent always correlated...
An interesting application of stiffness-strength-weight ratios I though about this year is driveshaft design. For example, if you're after a springy driveshaft you should use an alloy with very high shear strength and minimize Izz. It made me realize why aluminum driveshafts with high Izz could be potentially bad (even though you improve strength-to-weight). Titanium driveshafts could be an ideal choice given this goal.

[Adambomb]

Originally posted by Paul Achard:
IMO it's misleading to talk about density instead of modulus when considering second moments of area (Izz). The two arent always correlated...

Actually, shape factors DO take both density and modulus into consideration.


An interesting application of stiffness-strength-weight ratios I though about this year is driveshaft design. For example, if you're after a springy driveshaft you should use an alloy with very high shear strength and minimize Izz. It made me realize why aluminum driveshafts with high Izz could be potentially bad (even though you improve strength-to-weight). Titanium driveshafts could be an ideal choice given this goal.

There's a good chance of that. The methods I listed above allow you to quantify that. Use your stress or stiffness equations to create a metric based on materials properties, plot the metric on the provided logarithmic materials selection charts, and find which material has the highest value.

[Paul Achard]

I think I see your point. I just had the impression you were using both interchangeably.

Do you think you could write out a brief "Shape Factors for Dummies" breakdown? I haven't had the opportunity to learn that in class yet...

[MCoach]

The presentation linked by Adambomb do a good job at depicting things that you want to aim for shapewise for each condition. Put material where it is best to react it.

Torsion? Round tube.
Bending? I-beam.
Axial Tension? Solid, round, billet.
Axial Compression? Square tube.

Now beyond that, material comparison gets interesting...

I would also welcome a 'shape factors for dummies'.

[Adambomb]

Here's a class I put together a couple years ago that gives specific examples for the methods for determining material selection factors. This doesn't even truly get into shape factors, but you have the right idea.

The shortcoming in just looking at materials factors is that you are simply comparing materials for one pre-defined geometry. What if we want to, say, compare an Al c-channel with a steel rectangular tube? Now shape factors, in an absolute nutshell, are going to the next level to optimize a material/geometry combination. Unfortunately I never got a chance to make my own presentation to describe that. Hopefully this one on Materials Factors gets you in the right mindset to better digest the presentation I posted earlier. Looks like the "good stuff" on shape factors starts on slide 8 on that first presentation. In particular, check out the slide that compares the 2x4 to the I-beam. The ones following that give equations for different geometry, and with that you could easily make a spreadsheet to list them all.

Gonzo Racewerks Material Selection (http://www.public.iastate.edu/%7Eadambomb/Material_Selection.ppsx)

[Conor]

Interesting to see that this thread has been awaken from the grave...

Although material choice is key (Ti, CF, AL 7085), I think the more interesting dicussion pertains to the design freedoms now afforded through additive manufacturing. There's a lot of excitement on the horizon from this technology.