PLASTIC BUCKLING OF CYLINDRICAL SHELLS WITH CUTOUTS

The plastic behavior of an elastoplastic cylindrical shell with circular and rectangular cutouts under bending moment loads was investigated numerically and experimentally. A testing device (pure bending measurement) was designed and made to perform experiments on bending moment tests. The ratio of diameter to thickness of the stainless steel 304 specimens was 40.4 and the ratio of length to diameter was 7.94. The shape of the cutout on the shell was circular or rectangular. The tested specimens were categorized into five dissimilar groups. The effect of size, position and numbers of the cutout on the plastic moment is discussed. In order to investigate the strain distribution around of cutout, nine strain gauges were mounted in the longitudinal and circumferential directions on two specimens with different type of cutout. To investigate the accuracy of analytical and experimental results, numerical analysis considering the behavior of elastoplastic material were performed and good agreement was obtained between them. The strength of bending moment of cylindrical shells was decreased with increasing of sizes of cutout and it was increased with changing the location of the cutout from compression side to tension side. The effect of the number of cutouts (increasing from I to 3 (axisymmetrical)) on bending strength of tubes is negligible.