Hello,
I’m considering S-2 or S glass. Is it worth the effort with KK resin?
I found this in the archives:
http://www2.swaylocks.com/comment/1063156/Re-DaleSolomonson-S-glass-vs-E-glass
Seems like the elasticity of the resin is the key to seeing any advantage over E-glass.
Josh
Howzit Monkey, What kind of blank are you going to use. S glass is stiffer than E or Warp so using epoxy with S is going to change the flex factor and the blank can also affect the end product. Aloha,Kokua
Good point!
I’m doing up a stringless 2# Marco EPS.
What I’m curious about is KK’s elasticity meshing with S glass or S2. Bert’s tests seemed to suggest that resin was the key to seeing any advantage from S cloth.
Josh
speaking only in general.
i believe much of bert's position regarding flex was in regards to polyester vs epoxy.
....and EPS vs PU foam
it does make sense that the limiting factor for any particular sandwich design will be the material to fail first.
while the stress may be different in the various components of the sandwich. the elongation/stretch of all mating materials at any place in the matrix are identical.
So if one of the system components does not have suitable elastic limits it will ultimately fail and compromise the design.
more specifically.
glass fibers will stretch about 4-5% before breaking
(s-glass a bit more than e-glass)
but polyester resins typically have only 2-3% allowable strain. so they will fail before the glass has a chance to max out.
i belive most good laminating epoxy resins are good to as high as 10% allowable strain.
(i'd put RR in that category, but i'm not sure if that is principal reason you would choose them)
definitely use a good epoxy if you need to max out the load carrying capacity of the glass.
But as mentioned already the modulus and ultimate strength and dimensions of ALL your materials (fiber,resin, core ) will dictate the flex of your board
(ben thomas did a pretty good job of scoping out real numbers for that comparison)
regards,
-bill