Lets say you have a plain weave carbon fabric and wanted the same anisotropic properties lets say at 0 and 90 degrees but without the downfalls of a weave such as crimp. So you used unidirectional fabric at these specific angles. Would the result be similar but surperior to the weave since there is no crimp and fibers are as flat as possible?
You can achieve superior stiffeness with UNI tapes, but, while a fabric is intrinsecally balanced AND symmetrical, the tape is not.
This difference is very important to keep in mind whenever you decide the ply stack you intend to use.
And if you heat it, keep in mind the Poisson’s ratio too.
Would it still not be balanced if two sheets are layered at what ever angles but you only use a small portion. Like if a 1’x1’ ply is made but you cut and use only a small 1"x" sqaure from the center.
Stitched bidirectional uni where multiple layers of uni are stitched together. Pretty common in high margin applications. Plus flows resin well for VIP.
That seems exactly what I was looking thanks!
Also keep in mind fiber properties.
Wovens are mostly T300 or similar, and unis T700 or similar.
Large yacht hulls are often built with roll width uni carbon (pre pregs) and sandwich construction.
stiching reduces fiber’s adaptability to curves, etc. I prefer to use “normal” unis and building the arrangement I want by multiple layers on the desired orientation.
If you have a wide, big, heavy, cuasi-flat laminate, stiched unis will help to handle without fibre movement.
(I personaly only like multiaxials for big áreas and weights, is easier to handle)
Drapability of multiaxials is totally dependant on construction and stitching. A tricot stitching is much more drapable than regular chain stitching.
Also 90 degree stabilisation fibers are sometimes used to stabilise a biax45, actually to reduce drapability.
yes … biax may be a nightmare without proper stitching …