Showing papers in "Thin-walled Structures in 1988"
TL;DR: In this article, the behavior of thin, circular, isotropic elastic plates with immovable edges and undergoing large deflections was investigated by the numerical technique of differential quadrature, and approximate results were determined with the aid of a symbolic manipulation computer program and a Newton-Raphson technique to solve the nonlinear systems of equations.
Abstract: The behavior of thin, circular, isotropic elastic plates with immovable edges and undergoing large deflections is investigated by the numerical technique of differential quadrature. Approximate results are determined with the aid of a symbolic manipulation computer program and a Newton-Raphson technique to solve the nonlinear systems of equations. Bending stresses, membrane stresses, and deflections are calculated for clamped and simply supported flexural edge conditions and for a uniform pressure load and a concentrated load at the center.
101 citations
TL;DR: In this paper, an energy method was developed for studying the distortional buckling of monosymmetric I-section beams subjected to elastic restraints, and the buckling solution was developed in terms of an eigenproblem for four by four symmetric matrices.
Abstract: An energy method is developed for studying the distortional buckling of monosymmetric I-section beams subjected to elastic restraints. The buckling solution is developed in terms of an eigenproblem for four by four symmetric matrices. The distortional buckling of monosymmetric I-beams with translational, minor axis rotational and twisting restraint applied to the smaller tension flange is considered, and the solutions are compared with predictions which assume non-distortion of the cross-section.
39 citations
TL;DR: In this paper, an analytical technique is described for expanding a measured geometric imperfection surface in the buckling modes of a structure, which is applied to a channel section which buckles interactively in an overall flexural mode in the plane of symmetry and a primary local buckling mode.
Abstract: An analytical technique is described for expanding a measured geometric imperfection surface in the buckling modes of a structure. The surface is expanded longitudinally as well as transversely. In the transverse expansion, the constituent plates are treated as a plate assembly so that the imperfections of the individual plates can be interrelated. The technique is applied to a channel section which buckles interactively in an overall flexural mode in the plane of symmetry and a primary local buckling mode. The imperfection components of these modes are determined, as are the components of the secondary local buckling modes which may be triggered as a result of the interaction between the overall and local modes. The imperfection components are determined approximately from imperfection measurements taken at six points in each cross-section along the length of the column. The application of the technique to other cross-section types is mentioned.
33 citations
TL;DR: In this article, a potential energy functional for the non-linear flexural-torsional behavior of straight slender elastic beams with arbitrary cross sections is derived for situations where the strains are small and the Bernoulli hypotheses are valid.
Abstract: A potential energy functional for the non-linear flexural-torsional behaviour of straight slender elastic beams with arbitrary cross sections is derived. The result is generally applicable to situations where the strains are small and the Bernoulli hypotheses are valid. It is shown that special theories can be derived from the general expressions in a consistent manner, by neglecting some specific terms.
19 citations
TL;DR: In this article, a semi-numerical method for the analysis of orthotropic rectangular plates subjected to uniform, linearly-varying and partial inplane loads is presented.
Abstract: A semi-numerical method is presented for the analysis of orthotropic rectangular plates subjected to uniform, linearly-varying and partial inplane loads. The solution procedure is based on the classical method of separation of variables. The basic functions are chosen as the eigenfunctions for straight prismatic beams in free vibration. The two-dimensional governing partial differential equation is first reduced to an ordinary differential equation. The classical unidirectional finite difference method is then employed to solve the resulting ordinary differential equation. Results are presented for plates with different edge and loading conditions.
17 citations
TL;DR: In this paper, the authors presented several simplified methods of determining the strength and behavior of offshore cylindrical members and simple frames subjected to monotonic and reversed loading conditions, including the effects of the external hydrostatic pressure, the local buckling, the residual stresses, and the initial geometrical imperfections on the member behavior and strength.
Abstract: This paper presents several simplified methods of determining the strength and behavior of offshore cylindrical members and simple frames subjected to monotonic and reversed loading conditions. The important factors such as the effects of the external hydrostatic pressure, the local buckling, the residual stresses, and the initial geometrical imperfections on the member behavior and strength are all considered in the analysis. Typical results for the ultimate strength and behavior of these members and simple frames are given. Ultimate strength-design interaction equations recommended and proposed in the United States for different categories of beam-columns are also presented. The first part of the paper deals with the monotonic loading behavior and strength, and the latter part deals with the reversed and one-cycle loading behavior. Directions of further research are also indicated. In addition to an extensive citation of references in the paper, a Bibliography containing general references relevant to the subject area and reported recently in the North American literature is also included.
15 citations
TL;DR: In this article, the effect of delamination on the flexural stiffness of advanced composite laminates was investigated. But the results showed that the delaminations did not cause any degradation of the four-point bending stiffness.
Abstract: This paper presents the results of a study on the effect of delamination on the flexural stiffness of advancedcomposite laminates. Three- and four-point bending tests were conducted on graphite-epoxy laminates with embedded delaminations. The experimental results were corroborated with finite element method results as well as with simple beam theory models. The delaminations did not cause any degradation of the four-point bending stiffness. However, the three-point bending stiffness test showed that the delamination did degrade the stiffness by as much as 34%.
14 citations
TL;DR: Theoretical and experimental results for the buckling and vibration of three ring-stiffened thin-walled cones constructed from mild steel are presented in this article, where the cones were subjected to a gradually applied uniform external pressure until instability occurred.
Abstract: Theoretical and experimental results are presented for the buckling and vibration of three ring-stiffened thin-walled cones constructed from mild steel. For vibration, the study consisted of exciting the cones in air and while partially and fully submerged in water. For the buckling study, the cones were subjected to a gradually applied uniform external pressure until instability occurred.
12 citations
TL;DR: In this paper, a series of tests on ring and orthogonally stiffened thin-walled shells were carried out to investigate the collapse behaviour of the shells subjected to simulated damage and then tested under a combination of external pressure and axial compressive loading.
Abstract: This paper is the second of two parts describing the procedure of, and results from, a series of tests on ring and orthogonally stiffened thin-walled shells. The primary purpose of the work was to investigate the collapse behaviour of the shells subjected to simulated damage and then tested under a combination of external pressure and axial compressive loading. The test specimens consisted of two five-bay cylinders stiffened with plain ring stiffeners; two three-bay cylinders stiffened with T-ring stiffeners and two three-bay orthogonally stiffened cylinders, one with twenty stringers, and the other with forty. This Part II deals with the tests on the T-ring and orthogonally stiffened shells. It is concluded from the test results that the T-ring stiffeners were much more effective than the corresponding plain-rings with regard to limiting the deformations which would result from minor impacts and practical conditions of loading. It is generally recommended that plain rings should not be used in shells which form parts of structural components potentially liable to damage from a minor collision, etc. It is also recommended that further work be done, including analysis and testing, to determine the optimum design of T-ring stiffeners to limit the effects of damage in an effective manner.
11 citations
TL;DR: A theoretical study of the local buckling k of thin-walled girders with closed polygonal cross-sections is presented in this paper, where the load of the girder consists of compression, asymmetrical bending and shear.
Abstract: A theoretical study of the local buckling kof thin-walled girders with closed polygonal cross-sections is presented. The load of the girder consists of compression, asymmetrical bending and shear. The parabolic distribution of shear stresses in webs is included in the theoretical considerations. The energy method is employed and sine and polynomial series are applied to describe the deflections of any wall. A sample of the results of numerical calculations is presented for a girder with rectangular cross-section subjected to bending and shear. Some results for a girder under asymmetrical bending are also included.
10 citations
TL;DR: In this paper, the Marguerre large deflection thin plate equations are used to represent both the plate and the stiffener so enabling the lateral-torsional behaviour to be accurately modelled.
Abstract: The development of a numerical model describing the large-deflection elasto-plastic behaviour of flat plates and attached flatbar stiffeners including the effects of interaction is described in this paper. The Marguerre large deflection thin plate equations are used to represent both the plate and the stiffener so enabling the lateral-torsional behaviour to be accurately modelled. Complete interaction is achieved by satisfying the full set of equilibrium and kinematic conditions acting along the intersection.
TL;DR: In this paper, a more rational and accurate analysis for the torsion of braced thin-walled open section bars with transverse connections is presented, based on Vlasov's thin-wall beam theory in conjunction with the continuous medium method.
Abstract: A more rational and accurate analysis is presented for the torsion of braced thin-walled open section bars with transverse connections. The approach is based on Vlasov's thin-wall beam theory in conjunction with the continuous medium method. Shearing deformations in the middle surface of the thin wall are also taken into account. The analysis gives a generalized sectorial coordinate to estimate the realistic torsional stiffness of the thin-walled member, and provides a better physical interpretation of the relationship between the sectorial properties and the applied torque.
TL;DR: In this paper, a series of tests to determine the strength of small scale model, laterally unrestrained, doubly symmetric and monosymmetric beams is described, and the test results demonstrate that the current ultimate limit state design curves are conservative and will yield lower bound predictions with significant margins.
Abstract: A systematic series of tests to determine the strength of small scale model, laterally unrestrained, doubly symmetric and monosymmetric beams is described. The test results demonstrate that the current ultimate limit state design curves are conservative and will yield lower bound predictions with significant margins.
TL;DR: In this paper, the capacity of a plate to sustain shear load greater than the critical load was studied and the concept of effective width for square plates loaded in shear was developed.
Abstract: The capacity of a plate to sustain shear load greater than the critical load is studied. The concept of effective width for square plates loaded in shear is developed to consider rectangular plates loaded in shear. The deformation of the plate at failure is formulated. Very good agreement is observed between the theoretical results and experimental measurements carried out on aluminium web plates.
TL;DR: Based on a mixed variational principle and introducing the co-ordinate functions in the cross-section, this paper derived a method of solution for thin-walled members of open cross-sections in general bending and torsion.
Abstract: The classical theory of thin-walled members has been applied extensively in practice. Since the theory was based on the assumption of no shear deformation, it is unable to reflect some of the important phenomena such as shear lag in structures. In mixed variational principles, both stresses and displacements are taken as variables, and they create equal possibilities to yield good results both in stresses and in displacement. Based on a mixed variational principle and introducing the co-ordinate functions in the cross-section, a mixed variational method has been presented.1 Following this method, the method of solution for thin-walled members of open cross-sections in general bending and torsion is derived in this paper. This method is more general than the classical one and can be applied to members with rows of openings. It can also be applied to problems involving tension, bending and torsion actions, and simple analytical solutions in closed form can be obtained. Both warping and shear lag phenomena can be dealt with.
TL;DR: In this paper, a combination of numerical and analytical solutions in which the Rayleigh-Ritz variational principle and the Prandtl-Reuss equations are used are used.
Abstract: The paper is concerned with the theoretical prediction of the complete collapse behaviour of square plates, when subjected to in-plane compression. The plates are initially imperfect and four types of boundary conditions along their unloaded edges are considered. The method is a combination of numerical and analytical solutions in which the Rayleigh-Ritz variational principle and the Prandtl-Reuss equations are used. Numerical calculations have been carried out for different geometrical and material properties in order to compare this method and its results with other theoretical and experimental works.
TL;DR: In this article, the Rayleigh-Ritz method is extended to thin-walled structures on continuous supports by means of the combinations of frame modes transversely and continuous beam modes longitudinally.
Abstract: The Rayleigh-Ritz method is extended to thin-walled structures on continuous supports by means of the combinations of frame modes transversely and continuous beam modes longitudinally. Effects of warping, distortion and shear-lag are considered simultaneously. The thin-walled structure problem is reduced to simpler plane frame and continuous beam problems. Numerical results are compared to the finite element and finite strip methods. The present method is advantageous over both the finite element and finite strip methods in the reduced number of generalised coordinates and its ability to use the existing frame programmes to analyse thin-walled structures. No new elements are required to be generated.
TL;DR: In this article, an analytical method for thin-walled members of open cross-section in general bending and torsion has been derived, based on a mixed variational principle, and the solution of thin-wall members of closed sections will be presented.
Abstract: In a previous paper,1 based on a mixed variational principle, an analytical method for thin-walled members of open cross-section in general bending and torsion has been derived. In this paper the solution of thin-walled members of closed sections will be presented.
TL;DR: In this paper, a simple rigid plastic mechanism analysis, incorporating strain-hardening effects, is presented for the analysis of the plastic postbuckling response of a circular ring under external pressure.
Abstract: A simple rigid plastic mechanism analysis, incorporating strain-hardening effects, is presented for the analysis of the plastic post-buckling response of a circular ring under external pressure. Results are found to compare favourably with those obtained through more elaborate studies.