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This is Fig. 2 from the 2007 axialcomp paper. This slide shows the outer fiber effective stress (psi) at axial load, Nx= -3000 x 1.00516 lb/in. (-3000 lb/in is the applied uniform axial load Nx, and 1.00516 is the STAGS load factor PA.)
These results are from Case 4 in Table 4: no Koiter, yes change imperfection, ICONSV=1 . Shown here is the nonlinear equilibrium state from STAGS at the load factor, PA= 1.00516.
The imperfect shell has two initial buckling modal imperfection shapes:
1. a general buckling modal imperfection shown in Fig. 1a of the paper (similar to that shown two slides hence) with amplitude, Wimp1=+0.0625 inch, and
2. a local buckling modal imperfection shown in Fig. 61 of the paper (and shown 5 slides hence) with amplitude, Wimp2= -0.0005 inch.
Prebuckling bending of the imperfect shell causes redistribution of stresses among the shell skin and the stiffener segments.
Also, prebuckling bending gives rise to “flattened” regions with an “effective” circumferential radius of curvature that is greater than the nominal curvature of the perfect shell and that therefore causes early general buckling. (See the right-most expanded insert).
(From: AIAA 48th Structures, Structural Dynamics, and Materials Conference, Paper no. AIAA-2007-2216, 2007)
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