Young Modulus & Filament Winding

Hi Everybody,

Usually I am more involved in Fluid Mechanics, materials properties are a mysteriuous area for me, but I have to understand some basic before to go ahead with more advanced fluid dynamics, I need to gauge how big will be the mast diameter.

The application is slotted wing-sail for an A-Cat.

I know the filament winding company will use Toray T700 fiber.
It will be post-heated, but no autoclave.
I have no idea of the benchmark winding plan(0° / 90°/ 45°)
and do not know how to appraise the tube modulus: Is it a sum of layer modulus * Cos ?

The problem, is that the companies either have no software, either no time for such a dwarf order.

So I have to approach the optimum solution by myself looking for equation on wikipedia. Of course it can look a bit crude, but it is only one calculation.

Thanks in advance and best regards.

Erwan

 

Erwan,

There is no "equation on wikipedia" that could help you out. Laminate engineering involves complex matrix algebra according to laminate engineering science. People take whole college courses to learn laminate engineering. The laminate engineering is coupled with beam or column engineering mechanics principles (depending on whether your mast is going to be free-standing or stayed, respectively) in order to come up with the requisite laminate.

Actually, for what I think you want to do, it would be best to start with the basics of engineering mechanics first using some simplified overall laminate properties in order to determine the size and shape of your section, and then go into detailed analysis on the laminate later. You should consult a naval architect or composites engineer for proper guidance. I don't mean to give you an answer that is not an answer, but just to say that the answer is not simple--the engineering is complex.

Eric

 

Thanks Eric,

I though that it was straigtforward to make calculation for a tube between 2 free points, just considering the inertia of the section and the relevant modulus of the fiber according to its orientation (0/45/90°).

I consider the equation for buckling which is my main problem. I thought for a circular section it was possible to achieve a kind of abacus or a formula on Excel to make it, as long as it is the relevant assummptions.
For a circular section it seems to me it was a trade-off beween inertia from section area and thickness of the wall.

Regards

Erwan

 

http://www.gurit.com/page.asp?secti...ious Projects utilising composites from Gurit




Run it by these people they are about the best.

 

Erwan,

The strength and modulus will vary depending on the selection of orientation, and the selection of orientation will vary with the type of section. You asked for a slotted wing section, which is much more difficult to calculate moment of inertia and section modulus than is a round section. The two different sections will give you different bending and buckling behavior. You are right that there is a trade-off between diameter and wall thickness, and this boils down to having a threshold wall thickness to diameter ratio. The type of rig also plays a big part--if the rig is stayed, the calculations are for a column, and if the rig is unstayed, the calculations are for a cantilever. So a lot goes into it, and that is why I suggested going to someone who knows how to put all this together. It can be done on a spreadsheet, but it is not just one equation that you are working with.

Eric

 

Thanks Eric, War Whoop,
Apologizes for the misleading information: The rig will be a slotted wingsail, but the structure which holds it is basically a carbone telegraphic mast with a circular section and mostly compression loads due to righting moment, torsion loads are probably marginal.

It is hold by 4 shrouds with free rotating point at each ends

That is why I candidly imagined an Excel spreadsheet with the good assumptions could make it.

I had a contact with an architect & structural designer, unfortunatly, the cost of his study is around twice the cost of the filament winding tube in T700

So the trade-off is straigtforward; it is probably smarter to approach the problem using analogies, and keep the money for 2 prototypes.

For engineers and professional like you, I can give you this link, it seems very serious, because, behind it is EDF for its nuclear industry, their open-source business model can be attractive for specialist, not for me. I saw sowewhere some video either in English or with sub-titles, and the guys seems very deeply involved.

Thanks and regards

Erwan

http://www.code-aster.org/V2/spip.php?rubrique2

 

Erwan,

For your own research, why not try or borrow from the local library Filament Winding Composite Structure Fabrication by ST Peters, WD humprey, & RF Foral. Needs some digesting, not for light reading. It is about design. I bought this in SAMPE show some years back.

 

Thank so much RXComposite, that would be a perfect start and be cheaper than a prototype. I jump on Amazon right now.

Thanks and Regards

Erwan

 

There is also a software that I picked up for $200 that will analize tubes, squares, triangles, bars, ect. I think it is composite Pro but it did not became popular.

If there is a need, I have a publication of Properties of Advanced Composite Materials. In one section, there is a list of Mechanical properties and typical prices of Graphite fibers. T700S(12K) tow is 711 Ksi, 33.4 Msi modulus, cost 8-11 USD/lb. Toray T 1000G (12K) has better mech properties.

 

Those properties are for the naked fiber outside of a laminate matrix. Once laminated, the properties drop considerably. For standard modulus high strength carbon fiber unidirectional tape, one can expect a strength in the neighborhood of 90,000 to 100,000 psi, and a modulus of 10-11,000,000 psi at about 50% fiber content by weight. A carbon fiber cloth will be even less, as will any laminate with a mix of fibers and orientations. It is best to check sources of properties for actual laminates.

Eric

 

Thanks Eric. I hope he finds the book. It covers everything from macro mechanics theory, fiber properties, fabrication methods, environmental effects, testing, applications.

By the time he finishes it, he will be able to design rocket motor cases (at least in theory)

 

Thank you very much Eric and RXComposite.
I will try to get the software Composite-Pro, it seems cheap and could be insightful.
An alternative could be to aprroacg the optimum by analogies first.
I havve 2 examples:
On another forum Steve Clarke gave spec of the C-Cat Cogito carbone tube. So according to the difference in righting moment and distance between mast foot and the hound, it could be possible to scale down the tube.

18 years ago, a former Tornado gold medalist; Yves Loday experiment a A-Cat rig with a filament winding carbbon tube without spreaders and the sail had a luff pocket like windsurf sails. It was very light. The bottom part was 70mm outside diameter and the wall thickness was 3,1 mm, but the luff and leech loads on the mast were pretty similar than for a standard rig, and much bigger than for a wingsail loads.

The problem I have no idea on how much this thin tube bend (how much flexion), but it seems to ne small, so may be an 80mm diameter with 2,5mm thickness could make it without too much risk.

From the theoorical approach, I think the best to find the E*I and then ask the filament winding company what tthey can do.

Otherwise, as kindly suggested by RXComposite, "I will be lost in the wood" before to be able to desiign a rocket motor case.

Thanks to alll and best rregards

Erwan

 

May be the best solution would be to ask Steve Clarke , what kind of tube section he would recommend, and of course it woulld be a consulting service for fees, !!

It could make sense to have a generic structure for A-Cat /B-Cat /C-cat, and around it each wing conceptor will focuse on fluid mechanic issues like slot adjustment, twist trade-off (It will be quite easy, as any answer to any question is already on some forum).
And each boat using the Cogito-like twisting structure will pay a symbolic royalty to the conceptors (S.Clark D.Hubbart.. ) something like 50 to 100$ /year, or an up-front architect fees.

As the number of filament winding companies is quite small, it will be easy to implement.

Whithout any more structural issues, I feel confident the number of wingsail on the water is likely to grow faster.

As a positive side-effect it could federate the wing-sail community more formally, provide more bargaining power at ISAF if require.

Thanks and best regards

Erwan

 

Erwan, I've saved this for reference-might help for mast tubes and beam tubes: http://www.fiberfoam.net/Default.aspx?tabid=87