NUMERICAL MODELING OF BUCKLING OF RING-STIFFENED CYLINDERS

The questions regarding the most effective technique of modeling stiff ened shells persist despite the extensive literature available, In thi s study, ring-stiffened cylinders having widely varying radius-to-thic kness ratios are analyzed by using alternative approaches for determin ation of their buckling strength under pressure, The approaches consid ered here are 1) linear stability analysis using a two-dimensional mod el, 2) linear stability analysis using a three-dimensional model, 3) n onlinear bifurcation analysis using a two-dimensional model, and 4) no nlinear bifurcation analysis using a three-dimensional model, In-house computer programs based on p-version ring elements have been develope d for these approaches. A homogenization technique has been utilized f or treating composite laminates made of a large number of repetitions of a basic sequence of plies. The results are compared with those give n by currently available computer codes such as BOSOR, ABAQUS, and oth ers, For thin shells, linear stability analysis can significantly over estimate the buckling capacity, For moderately thick shells, the linea r and nonlinear approaches give close results for overall buckling but can differ significantly for local buckling. This is largely due to e nd effects where the buckling mode is localized, For two-dimensional m odels, the precise manner of connecting the shell and stiffener seems to be important, As may be expected, as the thickness of the shell or the stiffener increases, the two-dimensional models are found to be le ss and less accurate.