Influence of out-of-roundness on the critical loads of circular rings and circular tubes under hydrostatic pressure
Received:August 25, 2009  Revised:December 28, 2009
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KeyWord:circular ring  critical load  out-of-roundness  hydrostatic pressure  least squares method
邓长根 同济大学 建筑工程系, 上海
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      The in-plane buckling problem of a circular ring with symmetric fluctuant radius of curvature under uniform hydrostatic pressure is solved with Least Squares Method, and the critical load coefficients of antisymmetric buckling and symmetric buckling are calculated, respectively. The critical load coefficient of antisymmetric buckling is reduced by 67.71% for out-of-roundness parameter β=0.4. High precision formulas, the relative errors of which are within ±0.76%, of the critical load coefficients are obtained by minimum-relative-error data fitting. Based on the plane strain hypothesis, the critical load formulas are extended to a long circular tube with fluctuant radius of curvature under uniform hydrostatic pressure. The formulas are applied to the calculation of local buckling of a long circular steel tube, and the critical load is reduced only by 2.58% for the diameter fluctuating between the allowable maximum diameter and the nominal diameter.