monocoque hardpoints?

[Gustav]

Hi

Does anybody know a good way to make hardpoints on a sandwiched carbon monocoque?
pics, ideas... anything http://fsae.com/groupee_common/emoticons/icon_smile.gif

/gustav

[Gustav]

Hi

Does anybody know a good way to make hardpoints on a sandwiched carbon monocoque?
pics, ideas... anything http://fsae.com/groupee_common/emoticons/icon_smile.gif

/gustav

[MalcolmG]

one of the girls from RMIT (Bernadette?) did a project on hardpoints a couple of years back, see if you can find the report - I know it's floating around the net somewhere because I have a copy - anyway it shows a few different techniques for making hardpoints, and they were tested for performance - it's worth reading.

I've seen/heard of a variety of materials being used for hardpoints; solid carbon, polycarbonate, aluminium and plywood are all possibilities, and they all have their pros and cons.

[Gustav]

Do you have a paper copy or .pdf? Maybe you can email it to me http://fsae.com/groupee_common/emoticons/icon_smile.gif
>> gustavliden (a ) hotmail com

[Peter7307]

Yeah if you have a copy then either a pdf or an email would be great.

pathomas7307@hotmail.com

I chased round on the internet for about twenty minutes without success.

Cheers , Pete.

[Nik]

What core are you planning on using? I've used CoreCell high density foam core made by Gurit to make hard points before. I use their A300 (3lb./ft.^3) foam for general structure and then splice in peices A1200 (12lb./ft.^3) for the hard points. Add an extra layer or two of laminate in that area and bolt right through. It is always a good idea to use a backing plate or at least some fatty washers.

The engineers at Gurit tell me that they bolt 2000 hp diesels into big boats that way. I've made hardpoints for pedals and steering racks that way. No experience with sandwich panels and suspension points yet. Our team only uses sandwich panel stressed floors, not full monocoques.

[Gustav]

We have not yet decided which core we want to use. It would be great if somebody post some pictures showing details, or is that too secret? http://fsae.com/groupee_common/emoticons/icon_wink.gif

[smarby]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by MalcolmG:
one of the girls from RMIT (Bernadette?) did a project on hardpoints a couple of years back, see if you can find the report - I know it's floating around the net somewhere because I have a copy - anyway it shows a few different techniques for making hardpoints, and they were tested for performance - it's worth reading. </div></BLOCKQUOTE>

I've been researching quite a bit about a possible composite chassis, would it be possible if you could send a copy of that report my way?

Thanks heaps,
Joey

[SNasello]

There a bunch of ways to make hardpoints for a monocoque, and it varies depending on what kind of core you use. What you want to have in all cases is a reinforcement that will provide greater crush strength and compressive modulus and also lateral shear strength and modulus of the core. The reinforcement should be bonded to both outer skins. This will allow the core reinforcement to transfer the in-plane stresses to the skins. I dont have any specific information on various reinforcements, you should be able to do some calculations and tests to find out what is best for your application. Somethings you could use are a higher density foam, injecting honeycomb with a epoxy/high density filler, or UD carbon fibre blocks, just to list a few.

Also backing plates or big washers are a good idea when attaching anything, it will reduce the possibility of crushing the core when you tighten bolts down.

[nimdekvan]

i've been searching around about 3 days and didnt find any that related to RMIT carbon fiber monocoque report....so if anyone could send me a file would be great

justice2uall@hotmail.com

T_T


thanks alot

[smarby]

I have also been searching around on Google for the past few days and haven't found anything.

Did you transfer from RMIT Malcolm? If so I totally understand as it is your teams work.

[LU-Bolton]

Gustav,
Use a pan down at the bolted connection and add plies depending on what your testing/calculations show.

1.Lay outside skin into your molds as usual. 2.Lay core down into mold.
3.Pan down(inside of the chassis, btw) - Cut a hole in your core where the hardpoint needs to be. Bevel or taper the edges of that circle back so that fibers will lay easily over it. You're looking for no sharp corners here and a nice smooth taper. Now simply lay your inside skin just as you would have otherwise done into the mold. Again, you may need extra layers to build up this area. Calculations and testing come into play here.

Here is why you use a pan down instead of just inserting a hardpoint to replace the core.
Removing the core from the bolted location means that you have just removed several sandwich panel failure modes from your chassis at that location. Think of how much harder it will be to rip out one of those bolts from the chassis now that the inner and outer face sheets are connected. Without a pan down, you risk ripping the face sheet off of the core, which is a very real possibility and not how sandwich panels are designed to take load.

You can absolutely do this the way Nik describes. I did it on Lehigh monocoques for 3 years. Now that I have seen other efficient structures and have more experience, I would go with a pan down.

By the way, Kansas has been doing this with their monocoque. Take a look at some pictures online if you need some direction. It's very straight forward once you see it in person.

Test it. In less than a week you could build multiple panels and do some pull-out tests. Then you won't have to wait around for us to reply to your post.

Aaron Casssebeer

[MalcolmG]

about this RMIT hardpoints paper, I emailed RMIT to find out whether they minded me sharing it, obviously it's not top secret since we have a copy of it, but our team has had a pretty good relationship with RMIT since we started, we stayed with them our first 2 years of competition etc, so I thought we might've received it as a bit of a favour from them when we started doing monocoques. I haven't had a response yet, but once they give me an OK then I'll forward it on to all those who have requested it.

[Todd C]

I'd love a copy too, tclaybaugh@berkeley.edu. This is a really great thread, but I don't know what a Pan Down is. Where would I find more info on this?

Todd Claybaugh
Composites Team
Berkeley FSAE
fsae.berkeley.edu

[Peter7307]

Thanks Malcom.
Your efforts are appreciated.

Cheers , Pete.

[MalcolmG]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">I don't know what a Pan Down is. Where would I find more info on this? </div></BLOCKQUOTE>

I believe it's where you completely remove the core in the area of your hardpoint, (chamfering it down around the edges) and allow the inner and outer skins to come into contact in the area that is your hard point.

[Big Bird]

Greetings all,

Just in regard to the abovementioned report, we have had some long and serious discussions amongst the lads here and have decided we would rather not have the report being distributed around the net. Much of our design justification comes from the physical testing that we do, and this is a feature point of our Design Event presentations.

We have always tried to help out with advice wherever we can, and have very few "secrets" - look through the boards here and you will find a wealth of information from present and past members of our team. But the extensive material tests that we undertake are one of our team's "stocks in trade", and the said report has a little too much proprietary information in it for uncontrolled distribution. Essentially it is the basis for our structural equivalency report, which is getting a bit too sensitive.

I can say that if you are planning a composite structure of any sorts then such tests are a critical part of your design development. The test results that we have relate to the composite materials prepared at our uni, using our processes, and that are used in our cars. The data doesn't translate - that is why you need to do these tests to justify the safety and performance of your own particular design.

I hope the above doesn't seem too precious or secretive, and if any of you wish to speak to us at a comp or visit us you will find we are happy to discuss any aspect of our project. We just draw the line at distributing random copies of electronic documents, it is just far too easy for them to be copied and sent anywhere.

Cheers all,

[Bernatka]

wow...

i didn't realise my report was so sought after...
but don't worry if you cant get ur hands on it, its quite rather a boring read...

[MalcolmG]

...plus it's written in Australian, so must of you wouldn't be able to read it anyway (I have some Australia aunts/uncles so I learned when I was young)

[murpia]

Have a think about the judging process:

Team A: "We made a bunch of test specimens, tested them to destruction and used the results to inform our design process"

Team B: "We copied our design from those guys over there..."

Regards, Ian

[nimdekvan]

ummm ok. then i'll find another way to do the
structural equivalency report.
i just want the report only to lead the way how to compute something (cause its better to have some example)
but if you dont want it that way .. that would be ok . i really am understand
sorry if its sound like i plan to copy it.
thanks anyway.

[Pete M]

The hard way is more fun... do it from scratch, you'll learn a lot more.

[Bernatka]

The hard way definately is much more fun... even though making samples makes u want to pull ur hair out if it doesn't want to work... but testing them to destruction makes it all worth while...

Bernadette

[blister]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">
I believe it's where you completely remove the core in the area of your hardpoint, (chamfering it down around the edges) and allow the inner and outer skins to come into contact in the area that is your hard point.
</div></BLOCKQUOTE>

1. But if the core is removed, this section of the monocoque is thinner than the rest, unless you don`t add extra layers.

2. How do you put holes in there? Just drill from the outside (maybe with a big and accurate CNC Mill). Or do you position some bolts in your cnc`ed negative form?

[LU-Bolton]

blister,
Bingo! This is not a difficult concept, think about it. Sandwich panels are NOT good at taking out of plane loads. The a-arms are constantly transferring out of plane loads to the sides of the chassis, along with shear loads too.
When you start applying out of plane loads to sandwich panels it becomes very easy to rip off the face sheets. Have you ever tried taking a piece of sandwich panel with honeycomb core and ripping off a face sheet. It's not difficult at all.

If you don't believe anything I'm saying here than just try it and make some test panels.

Both methods will work if you do the work to prove them. All I'm saying is that if you can reduce the number of failure mechanisms or situations in which a composite can fail, it's a good thing. It should be a more efficient structure.

Use jigs to locate holes, again not difficult.

Just giving you guys another way to think about solving the problem.

Aaron Cassebeer

[rjwoods77]

Kai,

Malcolm said he got a copy from the internet so this may be a situation of not doing good document control. There are a number of "sensitive" info/papers I have received from helpful people from other teams but I don't leave it in my FSAE folder in my computer that copied to our teams database. Your correct on all points but if someone did post something sensitive on the net you cant really fault the persons from taking a look at it. Good thing Malcolm is someone who has loyalties to peoples feelings/trust.

Oh yeah. Germans have rabbits run in front of their race cars. Aussies have roos. I guess that means Canadians have caribou and the Yanks have deer and/or drunk NASCAR rednecks. Or maybe the Canadians have pools of maple syrup they have to dodge like oil slicks in RC Pro AMhttp://fsae.com/groupee_common/emoticons/icon_smile.gif God I love that game, especially with the NES disk controller.

[Kai69i]

Hi Rob,
We are aware of how the document was gained. As others have indicated by searching for days, it is not available on the net.

I would like to say thanks to Malcolm though for taking the time to email us, requesting if he could distribute the document electronically after receiving many requests for it. This was much appreciated, so thanks for your loyality and integrity. We look forward to seeing you all again in December.

Rob, I have not the slightest idea what you are talking about with the 'rabbits and roos'- I'll get Geoff to translate it for me on Monday http://fsae.com/groupee_common/emoticons/icon_wink.gif

Cheers,

Kai

[rjwoods77]

German touring cars a couple years ago a rabbit ran out in front of a car and got smashed to bits by a Mercedes and messed up the air dam pretty bad.

http://youtube.com/watch?v=VLXgTX55kUE&mode=related&search=

Then some stupid roo ran out in front of v8 supercars last week. By the way god bless you guys for having the real NASCAR. Save the taz. devils from that nasty cancer. I love seeing those things freak out on nature channels.

http://www.youtube.com/watch?v=nsBL51yj7ys

NASCAR.

http://www.youtube.com/watch?v=4DJpyTdiKPo&mode=related&search=

[Todzilla]

Couldn't agree with you more on that one Rob

[Moke]

I think that I might be able to shed some light on how we came to possess said thesis.

It was December the year 2005, and at great personal risk to himself, we sent one brave soul into the lion den. His task was to seduce "The Mark" and obtain the fabled "Thesis of Hard Points". Although his mission was a success, he has changed and is scared for life.

http://i241.photobucket.com/albums/ff157/moketv/IMG_0138.jpg

On a serious note we did not and will not steal peoples work. We have under taken our own testing and use only that information in events.

I doubt that Malcolm, this being his only 2nd year, realized that the thesis was not public. Those that received the report have left the team.

The team at RMIT is a very helpful bunch (even if they suck at skipping), who have put up with us over the last 3 years. I hope this misunderstanding won't hurt our teams relationship.

[Pete M]

Wow, an intellectual property debate. FSAE is growing up! http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

Well, anyway, I don't understand this business of sneaking around trying to get top secret data from other teams. Especially on things that the teams in question might not even consider that secret. Try asking!

I remember when we were at West 06 that the RMIT guys put all their hardpoint test samples on a big bench outside their pit and put yield graphs next to each one. I really don't think you could complain about their openness. Expecting them to part with a thesis containing their *interpretation* of those results is an entirely different proposition.

I personally am happy to help teams that are struggling with engine problems. I'm also happy to guide someone who is trying to analyse something. I'm even willing to discuss parts of our car and why we did things. But if you start asking for source code or ecu files... umm... not likely.

[smarby]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kai69i:
In fact, we are one of the few teams with competition wins that are prepared to discuss most technical details openly- I can think of two teams in Aus whom you wouldn't even think about approaching with such a request. </div></BLOCKQUOTE>

Sorry I am very new to this FSAE thing, my team is only 3 members at the moment and we are currently looking more at feasibility of different designs with very little research of our own to justify our choices.

I did not realize that asking for such information when offered was frowned upon and for this I'm sorry.

From this remark, can you recommend some teams that would be inclined to help new teams starting out?

Thanks,
Joey

[flavorPacket]

sorry, Joey, but there's no team that is here to help you. Building a functional race car from scratch in one year is enough of a challenge, and nobody's really looking to add to it.

Yes, some people may help you (including me if you ask something about bad control arm designs and upright jigs), but the point of this competition is for you to personally develop these skill sets. When you end up with a job in industry, you won't be able to ask the competitors what they're doing and why, so why develop a bad habit in FSAE?

The best way to build a car is to make a decision and go with it, then test, learn, and document. Don't spend all year thinking about what to do. Just build!

[Pete M]

Joey, it all depends on your definition of "help". There are plenty of people on these forums willing to give advice and talk about the advantages and disadvantages of different approaches. You'll also find plenty of people willing to help with basic stuff like getting an engine running ok or where to source materials.

If, however, your definition of help involves established teams giving you a DVD of detailed CAD models of their previous cars, along with a big pdf documenting the reasons behind their decisions, then i think you're somewhat missing the point.

This is an engineering design competition. So design the thing. Then build it. Then break it and learn what not to do next time.

[smarby]

Thanks for the tips, as I said I am new to this and now I'm starting to gather what you guys mean by help.

I guess what I meant was, what is the difference in help that Kai said. He stated that some teams are more likely to help out and there are others that you wouldn't think to approach.

So when I do get to the point where I have questions about different ideas, which teams should I ask?

[flavorPacket]

why don't you ask your own team? That is my and Pete M's point.

PS Kai was talking about the difference in reputations among a few of the more successful teams. You'll learn more about that as you become more involved in the series.

[smarby]

Ok, as I said before our team is only starting out now, we are not going for any comps this year and we only have 3 members. As I knew the least about engine/powertrain stuff, I was tasked with chassis and suspension. Again I am sorry if I have offended anyone, I'll go back to my corner now and continue reading. http://fsae.com/groupee_common/emoticons/icon_smile.gif

Joey

[ad]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by smarby:
Ok, as I said before our team is only starting out now, we are not going for any comps this year and we only have 3 members. As I knew the least about engine/powertrain stuff, I was tasked with chassis and suspension. Again I am sorry if I have offended anyone, I'll go back to my corner now and continue reading. http://fsae.com/groupee_common/emoticons/icon_smile.gif

Joey </div></BLOCKQUOTE>

smarby,

I think you may have miss understood the arguements by some of the previous poster's. They are not suggesting you no longer ask for advice (help) nor which specific team you should ask, rather, have a think about it, do some research and then approach the board (this forum) with questions in a general manner.

What Kai may have been refering too are some teams which do not like to talk on these forums for various reasons (team rules, etc).

As far as the thesis being distributed, unless its been intentionally uploaded and free for everyone to view, it should only be distributed by the creator, not another team. That was his argument.

I know of other instances were a team has intentionally stolen information and it is deeply concerning. If the team so decides to guard closely their intellectual property than thats their right and they have chosen to act upon it.

Just continue to ask questions... someone will give you an answer. Just not a manual :P

[Pete M]

If you feel hopelessly lost and don't know where to start, try contacting one of the teams near you and see if they'd be willing to let you come along to a test day. Failing that, make sure you go to a competition, even if you don't have a car. Most teams are pretty friendly, just be polite about it and remember that they don't owe you anything.

What school are you from?

[smarby]

Thanks ad and Pete,
I've been doing research all along, was just looking for a boost.

I'd prefer not to say Pete as the whole FSAE thing is still very up in the air where I am at the moment.

Joey

[PatClarke]

Joey, a new team has to start out like everyone else here. The only difference is there is a much greater database of information available now.
Research anything you can find, look at pictures. Look at your resources. Make some basic decisions and let it grow from there.
Basic decisions? First people, then money, then tyres, then engine.

Read the rules, then read the rules.

Sit down and consider your constraints, and with 3 members, boy do you have some constraints. You dont have enough potential drivers to compete in the dynamic events, let alone anything else.

I would advise against a carbon composite car for your first effort. I have nothing against them, but it is so difficult to change the car if you have to after testing. Cutting and welding is so much easier. When you have a handle on what makes a car work, then look towards composites. That is exactly what Kai's team did, and now after 7 years or so they are among the best in the world (Don't tell anyone, but their 2000 car was aweful!)

All the FSAE and Formula Student sites have useful papers and newsletters linked.

Remember the old saying 'You have to crawl before you can walk'

Good luck in your project, but for heavens sake, recruit some people.

Cheers
Pat

[Kai69i]

Hi Pat,
Totally agreed- the 2000 car was an absolute dog (awful is putting it very nicely!)

Most definitely a case of crawling prior to walking!

Joey, keep up the hard work and you will eventually get your rewards.

Cheers,

Kai

[Bertie]

a cheap easy solution is to use G10 which you can order to any size and thickness plate you want. its an epoxy fiberglass material cured under really high pressure. failing that use carbon. worked well for me.