Carbon Fiber Parts

Bloody awesomely good looking Groper !

Perhaps that is why so few actually sail their rigs... scared something is going to scrape it It's almost as bad as the land rover blokes that want to rough it in the bush, then half way down the mountain he locks brakes, jump out with a little weed scissors to clip the little twig just in case it is going to scrape the paint job

And btw, a practical application should never look like that. A shiny boat like that will give you arc eyes and it is going to be as slippery as hell.
That ssssss...*splotch* ! you hear was you sliding off the boat into the water.

I'm roughly half-way with the glass cutter. I cad-ed a whole thing up to be laser cut and then decided what the heck, I'm going to make it from pieces lying around my scrap yard. I still have to add a boom with which you can pull and retrieve the blade over the full length of the glass you're cutting, sideways it's 1m300 and if you cut 45o then it's going to be near 2m.

The frame where the car runs on can swivel around the one end so one can adjust the angle to anything you like.

 

Mistakes made, that I will fix later. The channel should have only 3 bearings (dummy !) that runs on the outside to ensure all the bearings make contact. No matter how precise you make it, with four bearings it's always like a dog lifting it's leg against a tree with one bearing standing up and not working.

 

It is because published values are most often quoted in Ultimate Tensile Strength (Uts). In marine application, when the laminate has fractured (or yielded), it is considered a failure. This yield point is about 50-60% of the Uts value if laminated with a good resin but falls to about 10-14% when a poor grade of resin is used.

With a good grade of resin, a safety factor of two would just about land you in the yield point. Bad choice because it would really translate to a safety factor of one.

This yield point is (based on standard strength formula of Classification Societies) is normally called the Ultimate Strength and must not be exceeded.

Just a matter of terminology.

First graph is for composite, second one is for metal.

 

You are right, I was equating ultimate tensile strength with Ultimate Strength.

Dino

 

Vacuum infusion gone wrong...

 

Just could'nt get uni directional to work for this one though.....

 

Suki, if you look closely at that guitar back, just above center and to the right, you'll see one of the biggest issues with working with this stuff. I suspect those are the laminator's fingers, as he tried to manipulate the fabric in place.

 

Actually PAR, it would be pretty hard to get one's fingers that side of the fabric! except after moulding. Certainly it is not perfect, but not far out and on the limit of what you can get this stuff to do. Might just be marks on the surface. I could have shot it in a studio or studio environment to get nice advertising quality images - without Photoshop!.

I will be making a couple more over the next year, including a smaller version so we shall see how they turn out. Main thing is just keeping everything so so clean when moulding as the fabric just picks up dirt so easily. Prototype has taken 20 tears use with no distortion and always fully stressed ie strung at concert pitch.

 

Where's the rest of the lessons RX ?

Have you given up or do you think I must give up



How do one know if a beam is strong enough, iow how much load, or how much bending is acceptable ? So if you load a part and it starts to bend, when do one know it's on the verge of bending too much ?

Most cats have only two beams. Is there something to gain by adding a third beam if one make all the beams lighter ?

 

To get the most from these types of materials, you have to do the calculations and physically engineer the laminate schedules to suit. Composites are generally highly engineered structures, which is part of the reason they're also expensive, material costs aside. JimBob and JoeLaryy can laminate up a carbon spar for you and it might be strong enough, but they'll likely not know how strong, until you break it and they elect to apply a few more layers of fabric, on the replacement. On the other hand, you can get a pro to do up the same schedule and it'll be lighter, probably stronger then the JoeLarry stick, though you'll have to pay for the engineering involved to get it to this level. There's absolutely no reason to use these materials and techniques, unless you need to for some reason. If you NEED to, then get it done right on paper first, if only to save materials and labor, to help mitigate the engineering costs.

 

Fanie, I am still working on it.

As PAR has said, it is a highly engineered structure and expensive. I would like to present it in a very simple way that can be understood withouth the calculations, or using the beam calculators that can be downloaded from the net.

For starters, I am concentrating on filament winding method of carbon fiber mast, closed ends, cantelever load model. With a mast diameter of 250-300 mm, wall thickness of 7.5 mm, there would be about 50 layers of ply. This will be divided into 4 sub layers, one for the inner layer consisting of hoops(90 degree), 2nd layer of axial wound(15 to 30 degree), 3rd layer of polar or 0 degree layer, last of +45-45 to wrap it up.

We have to start somewhere. What is your sail area/dimensions? How big is the boat or displacement so that the max righting moment (maximum force the mast will be subjected to) can be calculated.