Can someone explain in layman’s terms what shear is and how it can adversely affect a flat carbon panel?
In a solid laminate, shear is the stress that appear when one ply try to slide over the next one.
If you have a laminate and you flex it (imagine it reach a convex curved shape) the outer ply will describe an elongation while the inner will compress. Every intermediate ply will have intermediate elongation. Two next plies will try to length diferently, causing a shear stress between them. Paralell to surface.
In a certain line, it´ll be the change from compression to elongation, neutral line, with cero shear and no elongation/compression.
Max shear on both the outer and inner surfaces.
The resin has to support such stress by its worthy interlaminar shear strength.
To “see” it, think in a thick pile of papers same size, flat, in a table. Now intorduce an stick below the paper´s pile. You´ll see how each paper slides over the next to adopt the new, curved shape. The resin wouldn´t allow the sliding between plies.
Hope my bad english is enough to explain the concept.
Or in a sandwich construction you can also have core shear where the laminate could be fine but the core fails.
(In fact you HAVE shear on the core, from outer skin to inner skin. From max comp to max tenssion, linear transition thorough the thickness. Most important parameter on cores is just interlaminar shear strength)
Thanks guys, I understand what you’re saying. Well said.