Chassis design using honeycomb core
- Thread starter aaron.king
- Start date
John,
Very nice work you have done there!
May I ask if you have had a chance to get a preliminary weight yet and what that might be?
Again, nice work:thumbsup:
Best,
Scott
Very nice work you have done there!
May I ask if you have had a chance to get a preliminary weight yet and what that might be?
Again, nice work:thumbsup:
Best,
Scott
Seeing the mosler chassis, i thought about this idea more intensive, because it looks like a smart way to construct i chassis.
I recently discussed this with some friends of mine who are topspecialist within DASA for this kind of applications.
They told me that the don´t know of any case of pure structural construction made of honey comb materials.( Don´t mix it with laminated and in an autoclave baked constructions like F1 chassis)
The said the issue is the nonexisting flexibility within the material. all flexing loads are going on the glue seams and even withing the material as sheer between the layers.
Even the best glues have a point where they just pop of, And this is the main risk and unknown factor with this kind of construction. It certainly holds for a long time
but if it goes, it goes with a big bang and it is gone, there is nothing like a slow process.
So i would say very difficult to control even for the ones with big engineering and computing ressources.
TOM
I recently discussed this with some friends of mine who are topspecialist within DASA for this kind of applications.
They told me that the don´t know of any case of pure structural construction made of honey comb materials.( Don´t mix it with laminated and in an autoclave baked constructions like F1 chassis)
The said the issue is the nonexisting flexibility within the material. all flexing loads are going on the glue seams and even withing the material as sheer between the layers.
Even the best glues have a point where they just pop of, And this is the main risk and unknown factor with this kind of construction. It certainly holds for a long time
but if it goes, it goes with a big bang and it is gone, there is nothing like a slow process.
So i would say very difficult to control even for the ones with big engineering and computing ressources.
TOM
Exactly right Tom. The issue isn't will the bond between panels hold, it's more will the panel itself hold together as the loads are transmitted across the internal glue seams. The carbon skin tears away from the honeycomb fairly easily. Here I'm speaking of the range of carbon skin honeycomb panels that Boeing is currently testing and using - there are other manufacturers of carbon honey-comb panels producing panels with different structural characteristics (but I know from testing results that these are uniformly inferior).
Knowing that simply bonding panels together doesn't work reliably, you're left with using a combination of bonding and fasteners. And, like bonding, the fasteners will rip through the skins and honeycomb pretty easily if you don't mold in proper external and internal gussets in the right locations. Obviously, you can't just through-bolt without gusseting - the panels collapse quite easily with the point load.
As Tom indicated, with bonding only you'll get very little warning of failure. With bonding, gusseting and through bolting you'll get some warning, but it won't be a lot.
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One minor nit on this one, really a point of clarification - the original post concerned utilizing honeycomb composite construction. This is a smaller circle within the larger circle of use of advanced composites. Advanced composite construction also includes the use of carbon fibre laid up without the element of a honeycomb sandwich core. The techniques for optimizing either of these composite construction technologies are radically different. Honeycomb is a whole different ball of wax, and considerably more complicated to execute well than non-honeycomb sandwiched panels.
There are some notable examples of failed honeycomb designs. I know of a very expensive ($10,000,000+ in 80's dollars) racing sailboat produced in the early 80s with extensive use of aluminum honeycomb panels. With the first two hours of sea trials on SF bay, the keel ripped out and went to the bottom, the boat turtled and then started to come apart over the next 12 or so hours - turned out that seawater was unknowingly a solvent for the adhesive used to bond the aluminum skins to the honey comb (how can you miss that???). It was a wet day for the sailors on board. Ask me how I know.
There are some notable examples of failed honeycomb designs. I know of a very expensive ($10,000,000+ in 80's dollars) racing sailboat produced in the early 80s with extensive use of aluminum honeycomb panels. With the first two hours of sea trials on SF bay, the keel ripped out and went to the bottom, the boat turtled and then started to come apart over the next 12 or so hours - turned out that seawater was unknowingly a solvent for the adhesive used to bond the aluminum skins to the honey comb (how can you miss that???). It was a wet day for the sailors on board. Ask me how I know.
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Did you get wet Cliff.
Is that how you know.
What is the life of the adhesives used in these materials.
Jim
Is that how you know.
What is the life of the adhesives used in these materials.
Jim
Hi Scott,
Estimating the final weight of my chassis has proved problematical. The weight of the Mk4 chassis has been quoted as 85 lbs, but what does this include? I think this is the weight of the base honeycomb shell and does not include any of the mountings required to feed the loads into honeycomb. Also I do not think it include the front and rear sub frames, the rear cradle or the A and B pillar assembles. If you add all these bits I suspect the weight will be considerably more than 85lbs If anybody has any information about this I would be very interested to hear it.
Certainly my chassis will weigh more than 85lbs, but the weight will include the considerable additional weight of all the various mounting brackets for suspension etc. The weight of the honeycomb itself will be about 80lbs, but added to that is the aluminium filets used to hold it all together. I have erred on the side of safety with the suspensions brackets, so these are probably weightier than is necessary, as is the rear cradle. I will attempt to weigh what I have built so far which should give a fair idea (when I can work out how to do it). From all this you can deduce that I am not too sure what it will come out to weigh, but it will not be that light!
John
Estimating the final weight of my chassis has proved problematical. The weight of the Mk4 chassis has been quoted as 85 lbs, but what does this include? I think this is the weight of the base honeycomb shell and does not include any of the mountings required to feed the loads into honeycomb. Also I do not think it include the front and rear sub frames, the rear cradle or the A and B pillar assembles. If you add all these bits I suspect the weight will be considerably more than 85lbs If anybody has any information about this I would be very interested to hear it.
Certainly my chassis will weigh more than 85lbs, but the weight will include the considerable additional weight of all the various mounting brackets for suspension etc. The weight of the honeycomb itself will be about 80lbs, but added to that is the aluminium filets used to hold it all together. I have erred on the side of safety with the suspensions brackets, so these are probably weightier than is necessary, as is the rear cradle. I will attempt to weigh what I have built so far which should give a fair idea (when I can work out how to do it). From all this you can deduce that I am not too sure what it will come out to weigh, but it will not be that light!
John
Jim,
Yup, I did get wet.
One interesting add'l note on this thread that might prove helpful: the Jaguar XJ220 was built with extensive use of aluminum honeycomb panels in the chassis. I'm unsure of whether the body panels also used honeycomb construction. There might be something out there in google land showing a bit more of the construction details using the honeycomb panels.
Yup, I did get wet.
One interesting add'l note on this thread that might prove helpful: the Jaguar XJ220 was built with extensive use of aluminum honeycomb panels in the chassis. I'm unsure of whether the body panels also used honeycomb construction. There might be something out there in google land showing a bit more of the construction details using the honeycomb panels.
Oh Project Godiva is going along ok. Suspension will be finalised in two weeks, Constructions starts in earnest in 3 weeks and two months later I hope to have a rolling chassis...I have two months paid long service leave from work just to work on the car!
Panel construction is used in the Mosler quite well. The devil is in the detail and particularly the adhesive side of things. The carbon wings I have been making have alloy endplates for mounts and I use a toughened Araldite adhesive. The adhesion method requires degreasing, abrasion, degreasing, acid etching, washing off, washing off in demineralised water, drying and then use within two hours. The use of an organo-silane would also be useful.
However my chassis project is looking up witht he structural methacrylate adhecives comming onto the market. I suggest those who are interested look at Henkel/Loctite Speedbonder H2600
Godiva can be seen here: Race Magazine - Godiva - The Sneak Peek
Jim Rosenthal
Supporter
Instead of using aluminum honeycomb faced with plastic, which I think is what all these materials are, what about using a FRP honeycomb faced with FRP? That would be just as stiff, although a bit heavier, but the bonding issues would be less.
Jim,
Glass has a very low modulus (it's flexible), so it's usefulness in making a stiff chassis matrix is marginal. That's why carbon reinforcement revolutionized construction. It has a very high modulus, comparable with steel but much less dense.
Glass has a very low modulus (it's flexible), so it's usefulness in making a stiff chassis matrix is marginal. That's why carbon reinforcement revolutionized construction. It has a very high modulus, comparable with steel but much less dense.
Jim Rosenthal
Supporter
Got it. I had the impression that bonding to aluminum was one of the bigger problems, which is why I asked. There are some companies that make preformed composite structural elements. I don't know if anyone makes a preformed carbon honeycomb.
i have worked on vehicle which utilise honeycomb as the main structural chassis component or tub. The bolted connections should be applied thru bonded stainless steel mushroom inserts so that they have no direct contact with the the honeycomb. Your front and rear engine and subframes should be attached using spreader plates bolted and bonded to your tube. A cut and fold process for the honeycomb is best utilised for the manufacture of the tub. If you are clever with the way you design the chassis you can utilise off-shelf standard aluminium honeycomb panels. The adhesive if used correctly should be no problem. Most advanced adhesives need to be heated to key them. To reinforce the cut joints an angled piece of aluminium is often used. This protects the adhesive and overcomes any joint misalignment. The easiest way to construct this type of vehicle is to use the cills as longditudinal pontoons core out the honeycomb at the ends of the pontoon and bond in aluminium strips to which a closer plate can be attached. This then permits the rear to be used as a structural bulkhead to carry your engine/suspension subframes. An alternative is to extend the rear pontoon almost to the rear wheels and then plate the inboard sides with aluminium plate to which the subframe is attached. This type of construction was successfully used by Williams, McLaren, Ferrari, Porsche just to name a few. It is considered beneficial if the honeycomg used utilises two diffrent aluminium skin thicknesses. Meaning that the pontoon skin is a diffrent gauge to a bulkhead thickness. A slight difference in core thickness also has significant benefits
Take a look at page 85 of Karl Ludvigsen's The Inside Story of the Fastest Fords
It shows cross section examples of the changes made to the J car honeycomb chassis after Ken Miles unfortunate accident
I'm not sure if I can post a page of this book that has 2 good pictures, it's worth a look at an older technology for right angle seams
J6 may also have some relevant comments since he recently did a pretty good refurbisment of his MkIV chassis after 40 years of use
It shows cross section examples of the changes made to the J car honeycomb chassis after Ken Miles unfortunate accident
I'm not sure if I can post a page of this book that has 2 good pictures, it's worth a look at an older technology for right angle seams
J6 may also have some relevant comments since he recently did a pretty good refurbisment of his MkIV chassis after 40 years of use
Hi All,
Am new to this site and impressed with level of knowledge and projects. Am particularly interested in talking to anyone with experience in honeycomb panel chassis builds. Stef, and John you both seem to have really interesting and significant experience with it. Ok to ask some more questions?
Thanks
Am new to this site and impressed with level of knowledge and projects. Am particularly interested in talking to anyone with experience in honeycomb panel chassis builds. Stef, and John you both seem to have really interesting and significant experience with it. Ok to ask some more questions?
Thanks
Hi Maz,
I am also very intrested in the honycomb chassis, and have collected about 30 pics mainly from this site, and some from other sources
You may get more response if you send John or Stef a pm.
I have seen Johns chassis..........it is very intresting. and incredibly light....
Kenny Tompson, from the USA, is making some replicas of the J cars. His pics can be found on this site
If you want some pics ill email them to you, if you send me your email address
I hope this helps
mick
I am also very intrested in the honycomb chassis, and have collected about 30 pics mainly from this site, and some from other sources
You may get more response if you send John or Stef a pm.
I have seen Johns chassis..........it is very intresting. and incredibly light....
Kenny Tompson, from the USA, is making some replicas of the J cars. His pics can be found on this site
If you want some pics ill email them to you, if you send me your email address
I hope this helps
mick
