GESchwarz
Well-Known Member
Most of you know that I have been experimenting with methacrylates to bond aluminum skin to the airframe. While my testing continues I am considering my options for what type of ribs to use. I was thinking of conventional formed aluminum ribs with slightly oversized flanges of 3/4" or so, but after reading some literature I'm considering the use of PVC/Divinycell foam.
Like aluminum, adhesives are sensitive to stress risers in peel. So the best adhesives have some elasticity to them on the order of about 50% elongation. Well anyways, I was thinking of foam because a foam rib would more effectively distribute load over the entire width of the bond line than would a formed aluminum rib, where the strain would tend to concentrate along the web/flange bend line.
I have not yet handled this PVC foam material, nor do I know what density I should go with.
Exactly what sort of loading do the ribs take?
How can I compare the structural properties of a PVC foam rib to a formed aluminum rib?
I know that foam ribs have been used, particularly in sailplanes. Are they appropriate for a two-seater that goes 220 mph?
Like aluminum, adhesives are sensitive to stress risers in peel. So the best adhesives have some elasticity to them on the order of about 50% elongation. Well anyways, I was thinking of foam because a foam rib would more effectively distribute load over the entire width of the bond line than would a formed aluminum rib, where the strain would tend to concentrate along the web/flange bend line.
I have not yet handled this PVC foam material, nor do I know what density I should go with.
Exactly what sort of loading do the ribs take?
How can I compare the structural properties of a PVC foam rib to a formed aluminum rib?
I know that foam ribs have been used, particularly in sailplanes. Are they appropriate for a two-seater that goes 220 mph?
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