5HS Prepreg

General Composites Discussions Composites Talk
#1

I’m looking at getting some prepreg and am considering picking up a 5HS weave in 300gsm/9oz, as opposed to getting a regular plain weave or 2x2 twill. This is partially because the company that I’m ordering it from only has 5hs in regular stock for a 300gsm weight whereas they would have to order the dry fabric if I asked for it in 2x2.

So my question is - is there any reason I wouldn’t want to use 5HS in a prepreg application? It would actually be more drappable and have less crimp, and this more stiffness, than a regular 2x2, and since it’s a prepreg, it shouldn’t have any issues with loose fibers falling apart and just being a general pain to work with as a dry 5HS fabric would be. I have just never seen a 5HS used in a prepreg form before, and given benefits I listed above I’m just a bit nervous because I keep on thinking that I’m overlooking something that might detract from its usefulness. Anyone have any ideas? Why don’t you see 5hs used more frequently in prepregs?

Thanks

#2

The 5hs should be good to work with especially with curved surfaces. It us of the strongest wooven type and i dont see any reason not to use it.

#3

5HS isnt a balanced fabric, so you need to flip the fabric to make it symmetrical and balanced.

#4

That is right .
If you plan to use one layer then you got a problem.

#5

I was under the impression that a 5HS is actually symmetrical, and the bias is just dependent on whether you are looking at the a side or the b side of the fabric? Is that not true, and it is biased on both sides with 4 tows running in one direction and 1 tow perpendicular?

#6

The 0 degree is mostly on one side anx the 90 almost completely on the other (except where they cross). It’s more like a ply of 0 and 90 uni stacked together and “self stitched”.

A simple balanced layup would be A-side up, and then B-side up.

Any harness fabric, especially the higher number harness, is going to be less damage tollerant. Any hole (drilled or punctured) is more likely to fray or crack with a harness fabric than a plain weave. Still, it’s a good compromise between a woven and uni.