Local Buckling by Complex Finite Strip Method Using Bubble Functions

Bubble functions are finite element shapes that are zero on the boundary of the element, but are nonzero at the other points. They have been hitherto used to augment finite element formulations to obtain rapid convergence. The paper augments bubble functions to the ordinary semi‐analytical complex finite strip treatment in order to calculate the elastic local buckling stress of plate assemblies. The results show that the use of bubble functions improves significantly the convergence of finite strip method in terms of strip subdivision, and leads to much smaller storage required for the structure stiffness and stability matrices. Numerical studies are included, including long plates in compression and shear, a channel section in pure compression and shear, a stiffened plate, and an I‐section with a longitudinal stiffener. These studies illustrate the power of the bubble function based method for studying the elastic stability of plates and plate assemblies.