It is difficult to get effective section since both the panel and its ribs are rectangular and not square. When you say simple support is that on all four edges? The effective section is the inertia of the repeating cross section (including face sheet, ribs, and the bottom reduced flange). For...
Hi @Ferdiss
No, you cannot compute strain that way. Unlike a bar in pure tension under axial load, this is a beam bending problem where strain is maximum at the outer fibers of the beam at the beam center location. If you have a plot of load vs displacement z, you can get the 0.002 z yield...
If spring is linear, then F = kx and k is the same, a constant. Greater force gives greater deflection but k is constant and the same, as long as it is a linear spring.
You may have your answer by now but you are confusing tensile thread stress in the bolt and nut shear stress. The tensile stress is force/area independent of thread number.
The nut shear stress is force/ nut shear area which is pi x D x nut depth, usually three thread engagement
Let's say you apply M/3 to both ends - then the stress is M/3 times c/J. Since one end applies M then there is no equilibrium and rod accelerates since free to rotate. So max twist moment is M/3