Composite Experience
Discussion
Figured this kinda fits in with Kit Cars since some people do their own glasswork, might be a bit advanced tho.
I was wondering if anyone had any experience with Carbon-fiber composites with Kevlar/nomex honeycomb cores. And if so what kind of stuff did you use it in/on? I ask because I'm pondering a design of an extremely expensive (Skys the limit) monocoque, Mid-engined car as a time killer. Im thinking a blend of Evora/Ultima GTR/F1 racer. Still in the very infant stages (inside my head), hope to get something done on Paper/SolidWorks later this weekend.
Also-
Suggestions on Engine/Transmission set ups would be much appreciated. I'm leaning towards V8 territory.
Thanks,
-Matt
I was wondering if anyone had any experience with Carbon-fiber composites with Kevlar/nomex honeycomb cores. And if so what kind of stuff did you use it in/on? I ask because I'm pondering a design of an extremely expensive (Skys the limit) monocoque, Mid-engined car as a time killer. Im thinking a blend of Evora/Ultima GTR/F1 racer. Still in the very infant stages (inside my head), hope to get something done on Paper/SolidWorks later this weekend.
Also-
Suggestions on Engine/Transmission set ups would be much appreciated. I'm leaning towards V8 territory.
Thanks,
-Matt
Well for my sins i have spent nearly 30 yrs doing mainly f1 an have done chassis from the early days of flat sheet/fold up through forming round male moulds onto modern day female mould chassis
Also did the R15 an spent 3 yrs doing the Bentley speed8 so covered most things so what are you planning ? wetlay vac,oven/vac cured pre preg or full on autoclave (which is not as difficult as you would think these days)
Give me a rough idea an i will give you all the info i can ROB
Also did the R15 an spent 3 yrs doing the Bentley speed8 so covered most things so what are you planning ? wetlay vac,oven/vac cured pre preg or full on autoclave (which is not as difficult as you would think these days)
Give me a rough idea an i will give you all the info i can ROB
Rob,
At risk of hijacking the thread, I'd be particularly interested in the practicalities of making up a chassis using routed-and-folded honeycomb panels (how you jig the folds accurately, how the corners are bonded/stiffened once folded, jigging/positioning of structural inserts, etc.).
At risk of hijacking the thread, I'd be particularly interested in the practicalities of making up a chassis using routed-and-folded honeycomb panels (how you jig the folds accurately, how the corners are bonded/stiffened once folded, jigging/positioning of structural inserts, etc.).
Sam_68 said:
Rob,
At risk of hijacking the thread, I'd be particularly interested in the practicalities of making up a chassis using routed-and-folded honeycomb panels (how you jig the folds accurately, how the corners are bonded/stiffened once folded, jigging/positioning of structural inserts, etc.).
Me tooAt risk of hijacking the thread, I'd be particularly interested in the practicalities of making up a chassis using routed-and-folded honeycomb panels (how you jig the folds accurately, how the corners are bonded/stiffened once folded, jigging/positioning of structural inserts, etc.).
singlecoil said:
Sam_68 said:
Rob,
At risk of hijacking the thread, I'd be particularly interested in the practicalities of making up a chassis using routed-and-folded honeycomb panels (how you jig the folds accurately, how the corners are bonded/stiffened once folded, jigging/positioning of structural inserts, etc.).
Me tooAt risk of hijacking the thread, I'd be particularly interested in the practicalities of making up a chassis using routed-and-folded honeycomb panels (how you jig the folds accurately, how the corners are bonded/stiffened once folded, jigging/positioning of structural inserts, etc.).
The makers of the Taydec were considering this method some years back. They have a background in composite construction (race car tubs) so it might be worth seeing how they did it.
cymtriks said:
Staniforth has some thoughts on this in his "Race and rally car source book" but I suppose you have both read through that.
Unless I've missed something in a later edition, Staniforth only covers aluminium-skinned honeycomb monocoques, though?There's some similarly useful information in Tony Pashley's book, and an interesting Master's thesis here, but again, both concentrate on aluminium skinned panels.
Before the move to moulded tubs, Lotus used composite-skinned honeycomb panels assembled around a jig and I had an interesting conversation with Martin Ogilvie (Lotus F1 Chief Designer who was one of the key players in the development of this technology). If you've read any of the books on Lotus' technical history, you'll have doubtless come across photos of the chassis tubs for cars like the Lotus 88 being jigged up in this way.
Martin later went on to create a quick-and-dirty, routed-and-folded composite tub for an electric 'Westfield' called the Wisper, which inspired Westfield to commission his design of the FW400 (which also uses a lot of flat honeycomb panels in construction of its tub).
The way Martin described it to me, it was simply a matter of routing the panels then folding-and-gluing in an 'insert tab A into slot B' kind of way, and that a tub could be created very quickly and easily by this method, but I was always suspicious that 'easy' to an ex-Lotus Chief Designer might not be quite as straightforward for us mere mortals...
I haven't attempted any experiments, yet, but my main worry would be getting a composite panel to fold along the intended fold line, without cracking the outer skin, with enough accuracy to ensure that any previously positioned structural inserts are in the right place (though the obvious solution here is to slightly over-size any bonded-in hardpoints and to fit the dimensionally critical suspension bobbins afterwards).
I'd be very interested to hear the comments of someone who was involved in the manufacture of the early Lotus tubs, though.
I don't know much about honeycomb composites, or monocoque chassis design for that matter. I have done a f
k of a lot of routing though, especially with templates (made by me) and other guiding mechanisms so I shall look forward to learning more about this stuff, and especially whether it has any applications in the kit car world. Even if it doesn't, it's still very interesting stuff.
The problem with consulting books is that they tend to describe the way in which experienced, well capitalised manufacturers work and frequently don't describe enough of the basic processes to be of any help to people who want to start experimenting on a lower level.
k of a lot of routing though, especially with templates (made by me) and other guiding mechanisms so I shall look forward to learning more about this stuff, and especially whether it has any applications in the kit car world. Even if it doesn't, it's still very interesting stuff.The problem with consulting books is that they tend to describe the way in which experienced, well capitalised manufacturers work and frequently don't describe enough of the basic processes to be of any help to people who want to start experimenting on a lower level.
Edited by singlecoil on Sunday 20th June 12:58
Well I guess my knowledge of the subject is nill, so reading material would be a good start. Any suggestions? And I would like to know more about lay-up, as far as procedures, what works "best" and what doesn't work well. Sam 68's question would probably answer a lot of the questions I would otherwise ask but am not able to think of off the top of my head. Also, how scale-able are honeycombs in terms of making models?
I figured Balsa and the normal modeling materials would be best for small scale. I was thinking more along the line of like a halfscale model just for learning purposes. But as Ive learned from pricing this stuff is expensive as hell. Are there any materials that work well as an analog as far as workability of honeycomb?
At the risk of upsetting the " please don't advertise on this forum" police.....
I might be laying my hands on half a dozen full sheets of 15mm ally honeycomb next week. Will be very cheap. Could inspire one of you to "have a crack at it". Building a honeycomb monocoque, I mean.
More on that if it comes off.
Here are a few pics from my friends build. He is on the "Locostbuilders" site.
Doesn't look very "locost" to me though!
Geoff.
I might be laying my hands on half a dozen full sheets of 15mm ally honeycomb next week. Will be very cheap. Could inspire one of you to "have a crack at it". Building a honeycomb monocoque, I mean.
More on that if it comes off.
Here are a few pics from my friends build. He is on the "Locostbuilders" site.
Doesn't look very "locost" to me though!
Geoff.
AbusingTheMoog said:
Are there any materials that work well as an analog as far as workability of honeycomb?
We Architects (back in the good old days, before 3D modelling was something you did on a computer) used to make models out of foamboard, which is basically a layer of rigid foam with a thin face of paper. This would work as a pretty good analogue for a honeycomb panel and 5mm thick foamboard would be exactly the the right thickness to represent a typical 25mm thick honeycomb panel at a convenient scale of 1:5.It's dead easy to work with (even Architecture students can manage it...); you just cut it with a sharp scalpel against a steel rule and glue it.
It's not going to be anything like 100% accurate in terms of scaleability of stiffness, but it will give the same sort of workable approximation as building a spaceframe model from balsa.
spyder dryver said:
At the risk of upsetting the " please don't advertise on this forum" police.....
I might be laying my hands on half a dozen full sheets of 15mm ally honeycomb next week. Will be very cheap. Could inspire one of you to "have a crack at it". Building a honeycomb monocoque, I mean.
More on that if it comes off.
Here are a few pics from my friends build. He is on the "Locostbuilders" site.
Doesn't look very "locost" to me though!
Geoff.
He needs more rivets!I might be laying my hands on half a dozen full sheets of 15mm ally honeycomb next week. Will be very cheap. Could inspire one of you to "have a crack at it". Building a honeycomb monocoque, I mean.
More on that if it comes off.
Here are a few pics from my friends build. He is on the "Locostbuilders" site.
Doesn't look very "locost" to me though!
Geoff.
Right very sorry i havent replied sooner but been very busy with work an only just got a free sunday,I hope the OP is still here an also that im able to answer sam 68 an single coils querys.
The 1st composite tub made in the uk for f1 was lotus using the fold up method "mclaren beat us to the 1st tub in f1 but they had their tub made by hexell in the usa
There are several was to go about this but i will try an break it down as best i can,the 1st chassis was layed up on a 16ft sqr glass flat plate with 3 ply of carbon/kevlar,epoxy an 12mm nomex h/c vac bagged onto the laminate (this is the VERY early days of vac bagging an there wasnt even tacky tape avalible an all the seams,tucks were done with masking tape ! only pulled -10 vac but did the job)you then either stripped the cured sheet from the table an then layed up another skin an vac,d your previous sheet to it.Or you did it in 1 hit ply,core,ply with a glass/ali pressure plate on top to get a good finish on both surfaces
When you have your sheet the shape of the chassis was cut out an the fold lines routed on the inside (not all folds are 90deg but if you have a set thickness its easy to work out the width for a set angle
Chassis was then drilled using the drill jig,putting in the holes for the 400 odd 2 part bobbins that were used for fixings on the chassis. The early cars had ali bulkheads (engine seatback,dash an nose)an the fold upjig had bulkheads that matched those on the real car at these were also tapped,all the holes would/should line up so you could sit your sheet on the jig an using your bobbins bolt the sheet to the jig using the bobbins in the base of the tub.If you have everything in the right place your 1st 2 routed folds should be sitting either side og the jig showing open care cells,which were then filled with glue before the sides were folded up.Some of the bobbins in the side would be used to bolt the side to the jig an hold it in place,you then carried on gluing an folding both sides till they meet on the top of the tub
Sounds easy but the 1st tub took 24 hrs to fold !!! the good thing with wetlay sheets is its still "green" an fairly easy to fold,i did a chassis for lotus last year using a prepreg sheet an it was bloody hard work folding it up
Once the glue has set the bolts can be removed an the jig removed from the chassis,the inner corners of the tub was cleaned where the glue had squirted out an then carbon tape cevers the glue joins for extra strengh .Pontoons an lower seatback bulkheads were then bonded in before the ali ones were fitted
With a sheet being a set size you can add extra material in certain areas as you know where that area will be when its folded up or you can add extre material when its folded (see the rim of carbon put round the cockpit on sat a lotus 88 or 92
Martin ogilve,s car the wisper is stunning to see in the flesh an its a pity westfield didnt do more of them rather than the fw400 which was a wet lay bodge up by a bunch of cowboys
The 1st composite tub made in the uk for f1 was lotus using the fold up method "mclaren beat us to the 1st tub in f1 but they had their tub made by hexell in the usa
There are several was to go about this but i will try an break it down as best i can,the 1st chassis was layed up on a 16ft sqr glass flat plate with 3 ply of carbon/kevlar,epoxy an 12mm nomex h/c vac bagged onto the laminate (this is the VERY early days of vac bagging an there wasnt even tacky tape avalible an all the seams,tucks were done with masking tape ! only pulled -10 vac but did the job)you then either stripped the cured sheet from the table an then layed up another skin an vac,d your previous sheet to it.Or you did it in 1 hit ply,core,ply with a glass/ali pressure plate on top to get a good finish on both surfaces
When you have your sheet the shape of the chassis was cut out an the fold lines routed on the inside (not all folds are 90deg but if you have a set thickness its easy to work out the width for a set angle
Chassis was then drilled using the drill jig,putting in the holes for the 400 odd 2 part bobbins that were used for fixings on the chassis. The early cars had ali bulkheads (engine seatback,dash an nose)an the fold upjig had bulkheads that matched those on the real car at these were also tapped,all the holes would/should line up so you could sit your sheet on the jig an using your bobbins bolt the sheet to the jig using the bobbins in the base of the tub.If you have everything in the right place your 1st 2 routed folds should be sitting either side og the jig showing open care cells,which were then filled with glue before the sides were folded up.Some of the bobbins in the side would be used to bolt the side to the jig an hold it in place,you then carried on gluing an folding both sides till they meet on the top of the tub
Sounds easy but the 1st tub took 24 hrs to fold !!! the good thing with wetlay sheets is its still "green" an fairly easy to fold,i did a chassis for lotus last year using a prepreg sheet an it was bloody hard work folding it up
Once the glue has set the bolts can be removed an the jig removed from the chassis,the inner corners of the tub was cleaned where the glue had squirted out an then carbon tape cevers the glue joins for extra strengh .Pontoons an lower seatback bulkheads were then bonded in before the ali ones were fitted
With a sheet being a set size you can add extra material in certain areas as you know where that area will be when its folded up or you can add extre material when its folded (see the rim of carbon put round the cockpit on sat a lotus 88 or 92
Martin ogilve,s car the wisper is stunning to see in the flesh an its a pity westfield didnt do more of them rather than the fw400 which was a wet lay bodge up by a bunch of cowboys
Im very much still here. And I haven't stopped looking. I have exhausted the UCF Library as well as the many engineering databases we have. And have found next to nothing. Thank you for the reply. The lay-up process sounds time consuming and tedious to say the least. What I am looking for now is information on the load bearing properties of Carbon fiber composites (particularly corners, and bends) which has proven to be next to impossible. Everyone Ive talked to has been "afraid" I guess you could say to talk about their techniques and methodology because of I assume they don't want to give up the "trade secrets" which I understand. Thank you for sharing your information.
f1rob said:
the fw400 which was a wet lay bodge up by a bunch of cowboys
Oh dear, someone here isn't going to be too happy about that particular statement!Thanks for taking the trouble to write that lot out, I've tried to picture it in my head but I'm not really getting it. Probably better for me to stick to conventional stuff for the time being.
LOL its not easy to write either !!! but when you see it in action its fairly simple.
The original f1 tubs had ali jigs but done 2 now to rebuild old f1 cars an used a wooden jig an thats worked just as well an was 5% of the cost
If your old enough to remember its just like the fold up toys you use to get on the back of cornflakes packs in the 70,s where you had the shape marked on the packet with the fold lines,cut it out an folded into a 3d toy
,the pic,s of the ali tub earlier in the thread are a good example,but you dont need all those rivets with composites
Fw400 comments are true,sorry if it upsets but i watched those guys make those tubs,they were cowboys of the 1st order ! 1st composite tub they ever made an they never made another after that
Lots of people see carbon an to them its the black cloth from f1,dosent matter if its got polyester,vinylester or epoxy resin or if its wet lay,vac,d,oven cured or autoclave they all thinks its the same---its not
The original f1 tubs had ali jigs but done 2 now to rebuild old f1 cars an used a wooden jig an thats worked just as well an was 5% of the cost
If your old enough to remember its just like the fold up toys you use to get on the back of cornflakes packs in the 70,s where you had the shape marked on the packet with the fold lines,cut it out an folded into a 3d toy
,the pic,s of the ali tub earlier in the thread are a good example,but you dont need all those rivets with composites
Fw400 comments are true,sorry if it upsets but i watched those guys make those tubs,they were cowboys of the 1st order ! 1st composite tub they ever made an they never made another after that
Lots of people see carbon an to them its the black cloth from f1,dosent matter if its got polyester,vinylester or epoxy resin or if its wet lay,vac,d,oven cured or autoclave they all thinks its the same---its not
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