Strong beam design

General Composites Discussions Composites Talk
#1

Hi there!

My english arent super. I´m from Sweden you know.

Recently i came into contact with carbon fiber and i must say i am impressed!(Or i understod its advantages) But i have some wonderings.
I would like to build/produce a small beam. In its original form i has the shape of an I(an I-beam) and is made out of aluminum. It´s about ½" wide 2" high and 2’ long(15x50x1200mm). The “body” of the I-beam are about 8mm.
The stress that the beam have to take comes from all axels. Horizontal, vertical, twisting and turning you name it. But the worst stress comes “the natural way for an I-beam”. If you lay the beam across two chairs and sit on it. That is what i call “natural” stress. The beam has to have some holes in the “body” for axels and other things. Can that drasticly affect the durabillity of the pice?
What would be the best shape of the beam? I would prefer if the beam had the shape of a rectangular pipe. But i gues an oval shape would be best?

#2

My wife is Swedish and I lived in Malmö for a time.
So I have a few contacts in the South and the West of
Sweden. I could perhaps send you in the right direction.

Jim

#3

I live in the northern parts of Sweden. An hour drive from UMEA
If you know someone who could help with some consultation that would be great! But i dont want to hire someone to “do the math”. Not att this point.

This “devlopment” are on a hobby basis. Perhaps in the future it can become something to make a living on. It would cost to much money to hire someone to do the scientiffic devlopment work. I don´t mind larning by doing. But i WILL not start doing things if i dont have a clue. Does that sound smart?
What i want to have help with are basic stress resistant parameters.
If an aluminiumpipe like this(picture) is made out of carbon fiber it will get stronger i guess. If we assume it will get four times as strong will it be equaly strong if you would use four times less material?

#4

If you are thinking of making a full Composite “I” beam or square tubing, you are looking at major machine costs as those would have to be extruded. Or Pultrustioned…

For round tubes, you could “hobby” make them (we do them in the classroom with alum tubes, peel ply, Dunstone shrink wrapping, CF Pre-preg and oven curing) but you have to have some draft angle from one end to the other to be able to remove the composite part from the mandrel (tool).

Another way to make structural materials is getting too thin alum. tubing and get them composite winding / wrap like some soft water and propane tanks are.

I have asked our website “techy” here to look into a spell checker or langauge transferer, but no luck, yet.