Hi,
I have a question regarding the mechanical properties of braided sleeve and UD fabric .
Assume two carbon tubes with the same length, diameter, thickness will be made; one with two UD layers +/-45 and the other one with two layers of braided sleeves ( each braided sleeve +/-45). Both sleeve and UD fabrics have the same areal weight and the tubes will be made with hand layup process. Considering that in braided sleeves yarns are crossing each other in a single layer, will it have lower mechanical properties compared to the tube which is made from UD fabric?

thanks

Theoretically maybe (depending on the tube diameter), practically no. In reality it isn't that easy to get ud around a small diameter tube (as sleeve is an option I guess it's a small diameter) without wrinkling it, and even harder to get a second layer orthogonal to it without wrinkling the first. In comparison it's incredible easy to get the sleeve down right. The fibres of the sleeve run continuously around the tube, the ud fibres do not. An overlap 100% as strong as the continuous fibre has to be about 25mm, according to some research I've done at university. 25mm overlap is quite a lot for a small diameter tube and will result in a dysbalance in the area moment of inertia, acting as a nucleus for failure under torsion.
A reliable stronger option is to machine wind the tube.