GEOMETRIC EFFECTS ON SHAKEDOWN AND RATCHETTING OF AXISYMMETRICAL CYLINDRICAL-SHELLS SUBJECTED TO VARIABLE THERMAL LOADING

This paper presents results obtained from numerical simulations of the responses of an elastic-plastic thin cylindrical shell to fluctuating axisymmetric temperature in the presence of uniform axial stresses. T he engineering situation considered has practical importance in nuclea r reactors and has been the subject of a number of earlier studies. Th e main purpose is to assess quantitatively the influence of geometry c hanges, primarily due to plastic yielding, on shakedown and ratchettin g (incremental collapse) phenomena. In particular, these phenomena are investigated with respect to both the stabilizing effects of tensile primary stresses on them, and their strong interference with elastopla stic buckling. The systematic evolutive analyses presented herein are also intended to critically assess the validity of earlier results (ma inly condensed in the so-called Brussels diagrams) which have been est ablished by simplified methods of shakedown based on the small deforma tion (no geometric effects) hypothesis.