If I have a honeycomb sandwich sheet, and I need to be sure it doesnt flex or “pop” at extreme altitudes-
Can I simply drill a 1/16" hole in each cell to vent it? Or will it significantly weaken the structure? (1/4" cell)
using fiberglass right now (3-4 ply woven and mat) but can use CF if necessary due to this problem.
thanks!
Are you using vacuum/or autoclave?
Given the adequate adhesion to the core cell edges, altitude is not a problem.
Autoclave? Sorry, still a newbie. Is that oven curing?
I did wet layup and 150lb weights to press the honeycomb into the FG sheet & resin. Once cured- flip over and repeat.
I need to make sure there is zero flex or print-thru in the panel surface which would come from the air pressure in the cells. That’s why I would need to somehow vent it.
I see perforated honeycomb available, haven’t tried it. I thought it might be weaker since the vertical structure is weakened.
Is the effect of a 1/16" hole into a 1/4" cell enough to have any significant effect on strength? (drilled into the FG sheet, not the honeycomb wall.)
I have a finished product that I need to take to a few different people so they can qualify my work. Bad part is I didn’t consider altitude when I made this. If I made it in San Francisco, but I need to take it to someone on Mt Everest- I’m pretty sure the panel will flex from the air difference with sealed cells. Can’t have any flex in it.
So now I’m stepping backwards to fix this issue. Trying to decide if I should make extra-extra-extra reinforcements so I can vent it, or simply drill small holes into the existing piece.
If you would cure under vacuum, pressure inside would be vacuum if laminate is sealed. No worries about altitude there, if the laminate isn’t sealed, again, no worries. Even at sea level pressure, I can’t see the panel deforming under less pressure, with enough skin thickness. Easy to test though.
if i do vacuum bag, does the resin fill the cells? would the vac pressure cause the alu cells to collapse while curing?