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From:
Ahmet Zafer Senalp (Dept. of Mechanical Engineering, Gebze Institute of Technology, 41400, Gebze, Kocaeli, Turkey), “Investigation of the effects of geometric and load perturbation to buckling in multilayered torispherical pressure vessel heads”, Journal of Thermal Engineering, Vol. 1, Special Issue 3, No. 6, pp. 203-209, May 2015
ABSTRACT: The object of this paper is to investigate the effects of geometry and load perturbation to buckling in multilayered pressure vessel heads. The pressure vessel head in concern is thin walled torispherical geometry. Geometric and load perturbation can alter both the critical load for buckling and the buckled shape. Two and three layered torsispherical heads are considered. Two layered models include steel–aluminum and titanium–aluminum configurations and three layered models include copper–steel–copper configuration. Internally pressurized three-dimensional torispherical pressure vessel head model that is previously used in literature is constructed. As a first step eigenvalue solutions are obtained for each model. After this instability solutions with large deformation effects are conducted to obtain more realistic instability pressure values nonlinear. The solution is performed by finite element program ANSYS Workbench. In nonlinear analyses, perfectly plastic material model is used. It is concluded that geometric and load perturbations cause the instability pressure to decrease and cause the structure to buckle at a lower pressure value. It is also observed that for steel-aluminum configuration geometric perturbation is more critical than load perturbation whereas for aluminum-titanium the reverse is valid.
Notice that there are many, many circumferential waves in the buckling mode in the knuckle region of the pressure vessel head where the hoop resultant, Ny, is locally negative under the internal pressure.
In the post-buckling regime there are fewer isolated localized buckles, as displayed in several of the following slides.
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