I vaguely remember that fiberglass is stronger one way than the other i.e. if you wanted to reinforce a stringerless flextail, would you add more glass on the deck or on the bottom? (As I remember it, if you bend/flex it, it will fail on the inside of the curve rather than on the outside, right or wrong…???)
Compression failures seem to happen more often. It starts with a delam so layers are separated and weakened.
Thank you Lee. So in above example, to strengthen, I’d need to add layers on the bottom of the board…
Hey Doc, in a typical aircraft sandwich, compression failure is usually the first to occur, which, as LEED says, would be proceeded by the delamination of your surfboard top skin from the core followed by buckling of the skin.
I guess it depends what you mean by “strengthen”.
Do you want it stiffer or more impact resistant? I’d guess stiffer, but we’re dealing with a monocoque structure here, and possibly adding more glass either top or bottom will make it stiffer, thus bending less, thus being stronger.
Also, you might consider the rate of springback rather than just absolute stiffness… Just a quick comment about reinforcing to stiiffen a flex tail; skin compression will be one of your “weakest links” in the composite system. Carbon graphite has approximately the same tensile strength as glass but the nice thing about graphite is that it has almost equal strength in compression! whereas glass has almost none. So, you may consider laying graphite strips in key areas of the deck/tail. I did a lot of design and structural analysis when I worked in the aerospace industry utilizing graphite and other fibers. Strangely, Dr., one of the most useful design tools were the concepts behind leafspring design in the auto industry. Just take the spring stack apart and lay all the steel out with the longest strip in the center. You get an elliptical pattern, hmmmm. Place a patch of graphite in the shape of an ellipse in the right place and who knows, maybe you will get a lot of “drive” out of your flextail… (sorry, couldn’t help that one.)
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I guess it depends what you mean by "strengthen".Do you want it stiffer or more impact resistant? I’d guess stiffer, but we’re dealing with a monocoque structure here, and possibly adding more glass either top or bottom will make it stiffer, thus bending less, thus being stronger.
Really neither; more like durablity without loosing flex and snap. Guess that’s not really possible but increasing its life span would probably mean more stiffness. That should, with same materials, increase the snap back some too? Impact resistence not a factor.
You might want to look into using epoxy too. Especially w/carbon fiber.
Has anyone tried pre-forming carbon fiber with a slight curve to it, and then sandwiching it “flat” - so it would be “loaded” to push against the flex?
Taylor
Adding anything would increase stiffness, so…
Materials breakdown never stops, so maybe you need to add layers as it breaks down, instead of an overall cure one time right now.
That’s why flex tails were never embraced in surfing, they all look like homemade patch jobs after 20 days of usage.
Don’t care too much how it looks as long as it snaps back from a load and doesn’t break!