Instability Analysis of Torispherical Pressure Vessel Heads with Triangular Thin-Shell Finite Elements

1977 ◽  
Vol 99 (1) ◽  
pp. 64-74 ◽  
Author(s):  
V. L. Kanodia ◽  
R. H. Gallagher ◽  
H. A. Mang
Keyword(s):  
Finite Element ◽  
Nonlinear Analysis ◽  
Thin Shell ◽  
Experimental Result ◽  
Elastic Instability ◽  
Nonlinear Load ◽  
Linearized Problem ◽  
Shell Finite Element ◽  
Doubly Curved ◽  
Alternative Solutions

The elastic instability of an internally-pressurized cylindrical tank with a torispherical head is investigated using a triangular, doubly curved, thin-shell finite element. The formulation of the finite element, which is based upon cubic displacement functions and a modified principle of potential energy, is first described. Then, the element is verified by comparing numerical results for the linear, stable analysis to alternative solutions for the same problem. The subsequent instability investigation includes the solution of the linearized problem of equilibrium bifurcation, that is, of the classical eigenvalue problem, and a general nonlinear analysis, based on tracing the nonlinear load-displacement path. The critical pressure, obtained with use of the general nonlinear analysis, agrees closely with an experimental result as well as with a numerical solution stemming from an axisymmetric formulation.

Two-way coupling of thin shell finite element magnetic models via an iterative subproblem method

2020 ◽  
Vol 39 (5) ◽  
pp. 1085-1097 ◽  
Author(s):  
Vuong Quoc Dang ◽  
Christophe Geuzaine
Keyword(s):  
Finite Element ◽  
Field Distribution ◽  
Thin Shell ◽  
Iterative Procedure ◽  
Design Methodology ◽  
Content Type ◽  
Shell Models ◽  
Shell Finite Element ◽  
Corner Effects ◽  
Convergence Solution

Purpose The purpose of this paper is to deal with the correction of the inaccuracies near edges and corners arising from thin shell models by means of an iterative finite element subproblem method. Classical thin shell approximations of conducting and/or magnetic regions replace the thin regions with impedance-type transmission conditions across surfaces, which introduce errors in the computation of the field distribution and Joule losses near edges and corners. Design/methodology/approach In the proposed approach local corrections around edges and corners are coupled to the thin shell models in an iterative procedure (each subproblem being influenced by the others), allowing to combine the efficiency of the thin shell approach with the accuracy of the full modelling of edge and corner effects. Findings The method is based on a thin shell solution in a complete problem, where conductive thin regions have been extracted and replaced by surfaces but strongly neglect errors on computation of the field distribution and Joule losses near edges and corners. Research limitations/implications This model is only limited to thin shell models by means of an iterative finite element subproblem method. Originality/value The developed method is considered to couple subproblems in two-way coupling correction, where each solution is influenced by all the others. This means that an iterative procedure between the subproblems must be required to obtain an accurate (convergence) solution that defines as a series of corrections.

Stresses in the vicinity of an unreinforced mitre intersection: An experimental and finite element comparison

2007 ◽  
Vol 42 (5) ◽  
pp. 325-335 ◽  
Author(s):  
J Wood
Keyword(s):  
Experimental Investigation ◽  
Finite Element ◽  
Outer Surface ◽  
Thin Shell ◽  
Hot Spot ◽  
Bending Moment ◽  
Inside Surface ◽  
Elastic Stresses ◽  
Finite Element Approximations ◽  
Shell Finite Element

The experimental investigation reported provides elastic stresses in the vicinity of the unreinforced intersection of a single 90° mitred bend, subjected to an in-plane bending moment. The specimen was extensively strain gauged on the outer surface. A small number of rosettes were also laid on the inside surface close to the welded intersection. The procedures used for the successful installation of the inside surface gauges are discussed. In the experiment, consideration was also given to deflections and rotations. Satisfactory comparisons with adaptive- p thin-shell finite element results were obtained in general and differences are explained in terms of the known experimental variables and finite element approximations. The nature of the stresses at such intersections is discussed and various methods of obtaining fatigue ‘hot-spot’ stresses are considered.

scholarly journals Correction of thin shell finite element magnetic models via a subproblem method

2010 ◽  
Author(s):  
Patrick Dular ◽  
Vuong Q. Dang ◽  
Ruth V. Sabariego ◽  
Laurent Krahenbuhl ◽  
Christophe Geuzaine
Keyword(s):  
Finite Element ◽  
Thin Shell ◽  
Shell Finite Element
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