New Honeycomb Core Design

[djaytch99]

ALOHA ALL - NEW MEMBER HERE!

My business partner and I are the inventors of a new type of honeycomb core which we see as having applications in the marine, aerospace, building, and other industries. You can visit our blog where you will find information to help you understand how it works, and how it differs, quite dramatically, from other cores in play today. http://honeycombcore.blogspot.com/

We recently discovered (within the last 2 months) that we can create the core quite easily using vacuum forming techniques, and feel that this might be the way to produce large sections of core inexpensively and to a high degree of accuracy and quality using materials selected especially for the usage required.

We would greatly appreciate your comments and suggestions as to how we should proceed from here.

Thank you

DJH

[rxcomposite]

Great idea. From your site, the glue line or bondline was increased. Have you ran some test if the shear strength was increased? It seems by switching to flat tops, the configuration omits the glue fillet that forms around the honeycomb edges. This naturally occuring fillet increases bond strength.

In aerospace application, especially in greatly reduced atmospheric pressure, the trapped air (trapped at sea water level) will expand due to reduction in outside pressure at high elevation. This constant expanding and contraction causes strain in the bondline and other components of the cored laminate. The only way to eliminate this is to have self equalizing pressure. Hole in the cored laminate perhaps?

Shear strength is still the driving factor for cored laminate. Honeycomb structure still fall in the middle of the group of core (wood, honeycomb, plastic core) properties because of this. Another factor is elasticicity or deformation. See the dropped ball test discussion somewhee in this forum. Perhaps a cone type structure will increase shear strength? The cone type structure will form diagonals (triangles at cross section) similar to a bridge cross structure.

From the site, your design permits greater permeability by having open spaces by which air or water can flow around the structure. This is a no-no in the marine environment. Any breach in the skin will permit water to ingress causing the cored laminate to fill up with water. However, this permeability could be put to good use in double walled "fiberglass" petroleum tanks. The tanks are are constantly monitored for breach of surface from the outside and inside. While US, Canada, Europe has changed their steel water tank to corrosion proof tank storage, the rest of the world is still catching up. This is a big market.

[djaytch99]

Many thanks for your response - you make some valid points and some of them need clarification. No we have not tested our core as to shear strength or compression, but in the case of the former, it stands to reason that a "flattop" is by very definition going to have much more surface area on which to bond than any hexagonal rim, fillet or not. We ascertain that in some configurations, we would have up to 900% more contact area than traditional honeycomb.

You mention fluctuating pressure in the core in some applications. You will note on the blog that we are aware of this condition - we noted with dismay the failure back in 1999 of the X-33 NASA experimental launch vehicle developed by Lockheed Martin, which suffered from tank wall delamination -and concur that some type of perforations to allow pressure relief would be an approach to alleviating the problem. Also, if you look again at the blog in the section where we talk about metal foam "plugs", you will see that with these inserted, (see image) it would leave very little room for trapped air. Hexaflex has two very different surface configurations - one of these surfaces which we consider in many cases to be the "outside", has hexagonal pockets into which the hexagonal plugs made of metal or plastic foam can be inserted. They are then glued top and bottom acting as shear columns between the inner and outer skins. The foam plugs can be of variable density allowing exact elegant engineering (EEE).

You are correct in your analysis with regard to having water ingress into the core. Having the cored laminate fill with water however will not make the boat sink. With two skins and large vent channels running throughout the core (see image) it would be a simple matter of using compressed air to purge the core dry and effect a repair at ones leisure.!

Your final point regarding storage tanks we totally agree on, and in fact, it is one of the applications we covered in the patent. I guess we need to do some more research to find out who makes these structures and whether or not our core could be of real value to them.

We thank you once again for taking the time to respond to our posting. We will keep you appraised of our progress as we are talking to a number of people, both in Marine and other industries. Further input from you would be most welcomed. - Aloha

[rxcomposite]

Originally Posted by djaytch99

Having the cored laminate fill with water however will not make the boat sink.

Of course not as there are ships with double hull construction.

Glad you took the reply positively. As a designer, we are all always in search of a better material to use. Once you progress into material property stage, the designers can evaluate the product on what is the best application.

For double wall tanks, try searching petroleum tanks. I know at least of one manufacturer which is still active in this business. Beluga tanks.

[masalai]

djaytch99,
Following on what I imagined rx was suggesting, make the hexagonal 'cylinders' more as interlocking-trunkated-hexagonal-cones... I that possible? then, a layer of glass top and bottom would make for a quite robust structure with closed cells (not a disadvantage on boats) but would need to demonstrate increased strengths in all respects...

My next build will be in 'glass-covered-marine-ply' unless something better comes along that is stronger, cheaper and easier to work and attach things to...

My little piece of peace - internal images
My little piece of peace - more internal
My little piece of peace - still on the 'Jinker' ready for launching
My little piece of peace - launched and alongside at Bribie Marina
My little piece of peace - My boat bow on and 2 of a friends build on the next post, all using DuFlex and Foam cored products, glued with West system epoxy from ATL on the Gold coast of Australia...

[rxcomposite]

Originally Posted by masalai

Following on what I imagined rx was suggesting, make the hexagonal 'cylinders' more as interlocking-trunkated-hexagonal-cones... I that possible?

Exactly right. Similar to eggcrate design with truncated pyramid so when you look at the cross section, the webs are diagonals, something like 60 degrees. Similar to a bridge reinforcement. Of course, there will be reduced bond area.

Honeycombs are vertical columns so it tends to sway during shear loads. Attached are similar core profiles developed before.

[djaytch99]

I see where you are going with this

"Honeycombs are vertical columns so it tends to sway during shear loads."

I don't think a diagonal version is possible, however, if you look at the enclosed pics which show our early attempts at the vacuum forming process, you will see where insufficient vacuum has left fillet material. If this process was controlled better, I'm thinking you could shape these fillets into something that would contribute towards a sturdier column, but not sacrifice the surface bonding area.

[rxcomposite]

Yep. Something like that. But I am not saying this will be the cure. If development in your product proves that it can exceed the shear property of a typical honeycomb in the same specific weight/shear properties, you are well on the way to a better product.

[djaytch99]

Hi
On reflection it would appear that the inclusion of the compression plugs at spaced at regular intervals throughout the core (see image) would prevent the "sway". Also note that with these plugs inserted, the outward face has 100% bonding area with the skin, which would create a very satisfactory bond. Of course, as I believe someone mentioned, we really need to provide prototypes for analysis before we can confidently predict performance. We are working on this right now and will let you know the results.

[djaytch99]

http://honeycombcore.blogspot.com/Can you recommend appropriate materials for our samples cores to be created out of. We are eager to get some examples into the hands of the people who would be using it in a commercial setting.

thanks

DJH

[hoytedow]

This amateur was observing a programme about mega-yachts recently. The value of the honeycomb was exemplified in its use for non-load bearing decor within the ship. All finely designed furniture, "wood-work", mouldings, cabinets and the like were made of this material. The gentleman says the "whole boat" was made of this stuff. The result was a magnificently beautiful vessel of reduced weight.

2 minutes and 47 seconds into this video you will see the example I speak of.
http://www.youtube.com/watch?v=mYI2D...eature=related

[rxcomposite]

Seems somebody was toying with the same idea years ago. I saw this in JEC composite magazine year 2008.

[djaytch99]

Not quite the same but similar, I agree. Do you know if it has made any egress into the boating world? Seems like it should...

[rxcomposite]

No. I have not come across their product to date. I was just cleaning up my library and throwing away the clutters when i noticed that page so I thought it might be of interest.