ORIGINAL: Chuckr53-RCU
I'm just curious...why are they called "shear" webs? I thought the main goal of the shear web was to restrict the opposing lateral movements of the top and bottom spars under stress to add stiffness to the wing, to resist the bending of the wing when subjected to positive or negative G's.
That's what I thought.
If you apply an upward load to a wing, the bending of the wing imposes a compression load on the top spar cap and a tension load on the bottom spar cap. If we place a web between the top and bottom spar caps, that difference in tension and compression becomes shear in the web, hence the name "shear web"... clever, no?
Tension loads can be resisted until the spar cap reaches its max strength and breaks.
Compression loads are different. Take a soda straw, and place it vertically on a table while you press down on it from the top. Everything's fine as long as the straw is dead straight... Give it a tap across the middle, and the straw will fail at a load far less that its maximum tension failure load..... Since the top spar cap is in compression, it behaves the same way, and being firmly attachted to the shear web keeps it from failing in compression until its ultimate load is imposed.... HTH
Cheers!
Jim