Analysis of paraboloid of revolution type shell structures using isoparametric doubly curved shell elements

1990 ◽  
Vol 36 (5) ◽  
pp. 791-800 ◽  
Author(s):  
Bimalendu Ghosh ◽  
J.N. Bandyopadhyay
2021 ◽  
pp. 103028
Author(s):  
Masahito Takezawa ◽  
Yuto Otoguro ◽  
Kohei Matsuo ◽  
Tadahiro Shibutani ◽  
Akio Sakurai ◽  
...  

Acta Numerica ◽  
2001 ◽  
Vol 10 ◽  
pp. 215-250 ◽  
Author(s):  
Dominique Chapelle

This article, a companion to the article by Philippe G. Ciarlet on the mathematical modelling of shells also in this issue of Acta Numerica, focuses on numerical issues raised by the analysis of shells.Finite element procedures are widely used in engineering practice to analyse the behaviour of shell structures. However, the concept of ‘shell finite element’ is still somewhat fuzzy, as it may correspond to very different ideas and techniques in various actual implementations. In particular, a significant distinction can be made between shell elements that are obtained via the discretization of shell models, and shell elements – such as the general shell elements – derived from 3D formulations using some kinematic assumptions, without the use of any shell theory. Our first objective in this paper is to give a unified perspective of these two families of shell elements. This is expected to be very useful as it paves the way for further thorough mathematical analyses of shell elements. A particularly important motivation for this is the understanding and treatment of the deficiencies associated with the analysis of thin shells (among which is the locking phenomenon). We then survey these deficiencies, in the framework of the asymptotic behaviour of shell models. We conclude the article by giving some detailed guidelines to numerically assess the performance of shell finite elements when faced with these pathological phenomena, which is essential for the design of improved procedures.


Author(s):  
Juan Camilo Medina ◽  
Andrés Tovar

Topography optimization is an innovative technique that can significantly improve the response of certain type of structures. The most challenging aspect of topography optimization is the sensitivity analysis. In this manuscript two methods to approximate the sensitivities for problems in topography optimization are introduced. The gradient is supplanted with either a stochastic approximation, or a physical approximation. Initially, an overview of the state-of-the-art in topography optimization is presented, and some key issues are explored. Subsequently, the technique is outlined, and the proposed methods are introduced. Furthermore, a numerical example in which a structure composed of shell elements is subject to a blast load is provided. This example is solved employing stochastic gradient approximation, and approximate gradient. They are compared to the widely used finite differences approximation. It is possible to observe that the proposed method significantly reduces the computational effort required to solve the problem, while considerably improving the objective function.


Author(s):  
Vladimyr Meish ◽  
◽  
Yuliia Meish ◽  

Thin-walled shell structures in the form of plates and shells of various shapes have a high bearing capacity, lightness, and relative ease of manufacture. Three-layer shell elements, which consist of two bearing layers and a filler, which ensures their joint work, are widely used in mechanical engineering, industrial and civil construction, aviation and space technology, shipbuilding. When calculating the strength of three-layer shell structures with a discrete filler under dynamic loads, it becomes necessary to determine the stress-strain state both in the area of a sharp change in the geometry of the structure and at a considerable distance from the heterogeneity. The complexity of the processes that arise in this case necessitates the use of modern numerical methods for solving dynamic problems of the behavior of three-layer shell elements with a discrete filler. In this regard, the determination of the stress-strain state of three-layer shells with a discrete filler under non-stationary loads and the development of an effective numerical method for solving problems of this class is an urgent problem in the mechanics of a deformable solid. On the basis of the theory of threelayered shells with applying the hypotheses for each layer the nonstationary vibrations threelayered shells of revolution with allowance of discrete fillers are investigated. Hamilton-Ostrogradskyy variational principle for dynamical processes is used for deduction of the motion equations. An efficient numerical method for solution of problems on nonstationary behaviour of threelayers shells of revolution with allowance of discrete fillers are used. The wide diapason of geometrical, and physico-mechanical parameters of nonhomohenes threelayered structure are considerated. On the basis of the offered model nonstationary problems of the forced nonlinear vibrations of threelayered shells of revolution of various structure are solved and analysed. The basis of the developed numerical method for the study of nonstationary oscillations is the application of explicit finite-difference schemes to solve the initial differential equations in partial derivatives. The theory is based on the relations of the theory of three-layer shells of revolution taking into account the discreteness of the filler, which are based on the hypotheses of the geometrically nonlinear theory of shells and rods of the Timoshenko type.


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