The photos and links below illustrate one kind of analysis for predicting buckling of shells, an example of a computerized analysis of the static and dynamic buckling of shells, and advice about what to do as an engineer/designer faced with a system in which shell buckling is of concern.
Falstaff’s boots have experienced both nonlinear axisymmetric collapse (the top part of Falstaff’s left boot) and non-axisymmetric bifurcation buckling and post-bifurcation deformation (lower down in both boots).
Nonlinear static equilibrium state from a 360-degree STAGS model of a stiffened, imperfect cylindrical shell loaded by uniform axial compression and previously optimized by PANDA2. The shell has external T-shaped stringers and internal T-shaped rings. The imperfection is in the shape of the general buckling mode shape obtained by STAGS from a linear bifurcation buckling analysis. Prebuckling bending of the imperfect shell causes redistribution of stresses among the shell skin and the stiffener segments. This figure shows the outer fiber effective stress in pounds per square inch (psi) at the load (the “design load”) for which the shell was previously optimized by PANDA2.
An enlarged view of the region in which the external T-shaped stringers are modeled as flexible shell units.
An enlarged view of the deformed shell, showing the internal T-shaped rings. The prebuckling bending of the imperfect shell gives rise to “flattened” regions with an “effective” circumferential radius of curvature that is larger than the nominal radius of the perfect cylindrical shell and that therefore leads to general buckling at a load that is significantly less than that corresponding to buckling of the perfect shell.
- View more photos that illustrate concepts in buckling.
- Read the advice paper, on buckling.