Title: Creep Deformation And Buckling of a Circular Cylindrical Shell Under Axial Compression
Abstract: In a recent paper, FFA Report No. 100, a theory of elastic deformation and secondary creep of a circular cylindrical shell under axisymmetrical loads was derived, and an approximate criterion for buckling was proposed. The theory was based on the “1-membrane” analogy, and numerical solutions were derived for the special case of a “double-membrane” shell. In the present report, the general equations were solved for an arbitrary, odd number of membranes and the results were compared with those of the previous report. It was found that the double-membrane analogy yields an over-estimate of the deflection and stress rates, but the effect on the creep buckling time as calculated from the approximate method was small in comparison with the scatter normally obtained at creep buckling tests. Therefore, the double-membrane shell was found to provide sufficiently accurate results for practical use. However, if a higher degree of accuracy is wanted, the 3-flange model was found to yield a very close approximation to the solution provided by a multi-membrane shell. A few creep buckling experiments were carried out on thin aluminium-alloy cylinders under various stress levels. The number of circumferential lobes developed on collapse was found to decrease with a decreasing load level, and at a very low axial mean stress an axisymmetrical buckling configuration was noted. The approximate buckling condition proposed in FFA Report No. 100 was applied to the test cylinders and fairly good agreement with the experimental results was found.