Nonlinear Analysis of Shells by Finite Elements

Finite- and boundary-element linear and nonlinear analyses of shells and shell-like structures: A bibliography (1999–2001)

Procedures are investigated by which nonlinear finite element shell analysis algorithms can be simplified to provide more cost effective approximate analyses of orthogonally-reinforced concrete flat plate structures. Two alternative effective stiffness formulations, and an unbalanced force formulation, are described. These are then implemented into a nonlinear shell analysis algorithm. Nonlinear geometry, three-dimensional layered stress analyses, and other general formulations are bypassed to reduce the computational burden. In application to standard patch test problems, these simplified approximate analysis procedures are shown to provide reasonable accuracy while significantly reducing the computational effort. Corroboration studies using various simple and complex test specimens provide an indication of the relative accuracy of the constitutive models utilized. The studies also point to the limitations of the approximate formulations, and identify situations where one should revert back to full nonlinear shell analyses.

Nonlinear large deformation analysis of shells using the variational differential quadrature method based on the six-parameter shell theory

Geometrically nonlinear analysis of laminate composite plates and shells using the eight-node hexahedral element with one-point integration

A three-node C 0 ANS element for geometrically non-linear structural analysis

A refined non-conforming triangular plate/shell element for linear and geometrically nonlinear analysis of plates and shells is developed in this paper based on the refined non-conforming element method (RNEM). A conforming triangle membrane element with drilling degrees of freedom in Cartesian coordinates and the refined non-conforming triangular plate-bending element RT9, in which Kirchhoff kinematic assumption was adopted, are used to construct the present element. The displacement continuity condition along the interelement boundary is satisfied in an average sense for plate analysis, and the coupled displacement continuity requirement at the interelement is satisfied in an average sense, thereby improving the performance of the element for shell analysis. Selectively reduced integration with stabilization scheme is employed in this paper to avoid membrane locking. Numerical examples demonstrate that the present element behaves quite satisfactorily either for the linear analysis of plate bending problems and plane problems or for the geometrically nonlinear analysis of thin plates and shells with large displacement, moderate rotation but small strain.

Investigation of the nonlinear dynamics of thin sandwich shells composed of functionally graded materials with double curvature in thermal environments

In this paper, a mixed spline boundary element and finite element method is suggested to analyse non-linear bending of plates and shells. Only the fundamental solutions for plates are required in order to establish the boundary integral equations. A quadratic rectangular spline element is adopted to deal with the membrane effects of plates and shells. Numerical examples show that the approach developed in this paper is very effective and especially promising for the non-linear analysis of plates and shells.

Geometrically non-linear analysis of arbitrary elastic supported plates and shells using an element-based Lagrangian shell element

This paper provides information on hyperboloids of revolution surfaces and their classification, using methods of differential geometry and computer design. All surfaces are plotted by means of computer graphics. The geometric nonlinear numerical analysis of thin shells in the form of hyperboloid of revolution surfaces on buckling resistance and stress-strain state is given in this paper, using the finite elements method in a computer software. Comparison is done with the result of the finite elements linear analysis of their buckling resistance.

A Geometric non-linear analysis of composite shells under thermomechanical loading has been discussed here. From the literature, it may be seen that the thermal stress analysis of structural elements has continued to remain a research topic for a couple of decades. No one computationally verified the geometric non-linear buckling of composite shells under thermomechanical loading using semiloof element. In this work, linear buckling analysis of Kari Thangaratnam (2) is extended to geometric non-linear analysis of composite shells under thermomechanical loading. A general shell element called the semiloof shell element has been extended to thermal stress analysis of laminated shells. The formulation is based on nonlinear theory and the finite element method using semiloof element. The validation checks on the program are carried out using results on homogeneous isotropic shells available in the literature. The parameters considered in analysis are (1) number of layers in the laminate, (2) Lay-up sequence (symmetry, antisymmetry, cross-ply etc.), (3) Fibre orientation angle, (4) Different aspect ratios, (5) Orthotrophy ratio, (6) Boundary conditions (simply supported, clamped and combination of boundary conditions).

The nonlinear analysis of thin-walled shells is not a rarity, particularly the nonlinear strength one. Many works are devoted to linear and nonlinear analyses of shells of classical form: cylindrical, spherical, hemispherical, shallow, conical. The concept of shells of complex geometry appears when the coefficients of the first and second quadratic forms of their middle surfaces are functions of the curvilinear coordinates. Concerning nonlinearity, it is generally accepted that four different sources of nonlinearity exist in solid mechanics: the geometric nonlinearity, the material nonlinearity and the kinetic nonlinearity. The above theoretical aspect of the nonlinearity, applied to a sinusoidal velaroidal shell with the inner radius r0=1m, the outer radius R=20m and the number of waves n= 8, will give rise to the investigation of its nonlinear buckling resistance. The building material is a concrete. The investigation emphasizes more on the material and the geometric nonlinearities, which are more closed to the reality. Finite element model of the shell consists of 6400 elements and 3280 nodes, the total number of nodal unknown - 18991. For surface modelling was used flat shell elements with six degrees of freedom in the node. The boundary conditions cor- respond to hinged bearing on the outer and inner contours. The result of the investigation is the buckling force of the shell under self-weight and uniformly vertically distributed load on its area, the corresponding numerical values of displacements and the buckling mode

Nonlinear analysis of FG-sandwich plates and shells

Geometrically nonlinear analysis of shallow shells using higher order finite elements

In this study, the nonlinear free vibrations behaviour of nano-truncated conical shells was analysed, using the first-order shear deformable shell model. The analysis took into account the structure size through modified strain gradient theory, and differential quadrature and Fréchet derivative methods in von Kármán-Donnell-type approach to kinematic nonlinearity. The governing equations were obtained, utilizing Hamilton's principle. Partial differential equations plus the non-classical and classical boundary conditions were used to obtain the shells’ equations of motion. Discretizing the boundary conditions and equations of motion were performed based on a generalized differential quadrature analogy. The eigenvalue system was considered based on the harmonic balance technique. The Galerkin and Fréchet derivative approaches were used to determine the nonlinear free vibration behaviour of the carbon nano-cone, which was modelled in the simply- and clamped-supported boundary conditions. Comparisons were made between the findings from the new model versus the couple and classical stress theories, indicating that the classical and modified couple stress theories are distinct representations of modified strain gradient theory. The results also revealed that the degree of hardening of nano-truncated conical shells in the modified strain gradient theory is less than that of modified couple stress and classical theories. This led to a rise in the non-dimensional amplitude and frequency ratios. This study investigated the effect of size on free nonlinear vibrations of nano-truncated conical shells for various apex angles and lengths. Finally, we evaluated and compared our findings versus those reported by previous studies, which confirmed the precision and accuracy of our results.