I noticed that my new epoxy (laminate over foam, not sandwich construction) flexes a little where there is denting, and wondered what the properties of a thin layer (2-4 mm?) of EVA between, say, two layers of 4 oz s-cloth would be? not for a whole board, but as kind of an under the glass stomp-patch on the deck? Anybody ever try EVA as a sandwich core, and if so what were some of the properties of the resulting sandwich? could it be a way to add flex to a sandwich-core type of board? or would the resultant loss in strength be too much of a compromise?
Wacky I know, and I’ll probably just test it and see what happens, but thought I’d check with the list first…
Although I appreciate the intention of distributing flexural energy by absorbing the load I think that a foam sandwich core should have a robust shear resistance. In addition, panel stiffness will distribute energy through a widened load path. With that said, energy could be absorbed in time-wise fashion (like a bumper) like what you see with traction pads. Conceivably one could coat a surfboard that is glassed with a layer of absorbing foam aht would act as an absorbing layer. By glassing this soft outer layer, the new layer of glass has very little support beneath it. The load will not distrubute very much below the given area, and the outer skin will most likely fail. in summary, the EVA foam core wion’t work so good.