1,604 research outputs found
On the conforming and nonconforming finite elements for buckling of plates, plates on elastic foundations and cylindrical shells
No full textPaper presented at the 1970 Conference on Finite Element Techniques in Structural Mechanic
Algorithm for the large deflection of geometrically non-linear, plane and curved structures
No full textLarge deflexion, geometrically non-linear finite element analysis of circular arches
No full textThis paper presents the results of an investigation into the geometrically nonlinear behaviour of circular arches. A curved element is used, based on satisfying the condition that the circumferential strain and change in curvature, rather than the displacements, should be simple independent functions of the co-ordinate axes. The analysis was carried out using the linearized incremental method based on the mid-increment stiffness in conjunction with the Newton-Raphson iterative technique. A comparison is first made between the results obtained with this element and those using a simple polynomial shape function. The behaviour of a range of arches is then considered and the results are compared and found to agree well with an analytical method. The results include the behaviour of deeper but still shallow arches which exhibit “looping” of the load-deflexion curve, and bifurcation of the equilibrium path into unsymmetric deflexions of the arch.A computer program was developed to allow any of the generalized degrees of freedom which are designated for incrementation to be expressed as either forces, to avoid failure at the vertical tangent to the load deflexion curves, or as generalized displacements to avoid failure at the horizontal tangent. The program also allows the quantity subjected to incrementation to be changed as necessary to follow complex load-deflexion equilibrium paths.<br/
A curved cylindrical shell finite element
No full textA simplified form of Cantin and Clough's cylindrical shell element, reducing the size of the element stiffness matrix from 24 × 24 to 20 × 20, is presented, and the two elements compared by solving several problems. Comparison is also made with results obtained from triangular elements, presented by Cowper et al. (1970). If a parameter based on solution time is used as a convergence criterion instead of the number of degrees of freedom, the new element is found to be superior to all others considered. The new element has the added advantage over that of Cantin and Clough's and all other high degree displacement function finite elements, that it avoids boundary conditions that have no obvious corresponding forces.<br/
The applications of finite elements to large deflection geometrically nonlinear behaviour of cylindrical shells
No full text
Good Words (Magazine) for 1868
No full textAs Abbey writes, the fable articles here precede and are different from their first appearance in book form a year later. For it was then that Ralston published the first edition of Krilof and His Fables. See my comments on the third (1871) and fourth (1883) editions. The book smells of its many years! The three fable articles are on 39-46, including six illustrations on 40-41; 215-221, including six illustrations on 216-17; and 413-20, including six illustrations on 416-17. These are magazine articles. They comment on Krilof's views and particularly on Russian foibles. Thus one prose text after another is integrated into the article. In the book, there will be, after a preface and a memoir, a simple collection of texts. In fact, the selection of Krilof fables within the article here is excellent, and the author puts them into a good cultural and political context. At least some of the illustrations are the same as those in the third edition.. The texts are close to those found in the published books. It makes sense to see the texts in the magazine here as forerunners of those fable texts there. I presume that Ralston had opportunity to edit and amend between his magazine articles and his book's first edition. The publisher of the magazine is of course the publisher of the third edition that I have. The print is minuscule! I needed a magnifying glass for normal reading. The index just after 774 assigns J.B. Zwecker and A.B. Houghton as illustrators for the eighteen illustrations in the three fable articles. Dalziel, Houghton, and Zwecker are the names I can make out on the illustrations. Dalziel is not mentioned on the title page, but there is reference to others.This is a hardbound book (hard cover)Norman MacLeod; W.R.S. Ralston for fable
Simple drag prediction strategies for an Autonomous Underwater Vehicle’s hull shape
No full textThe range of an AUV is dictated by its finite energy source and minimising the energy consumption is required to maximise its endurance. One option to extend the endurance is by obtaining the optimum hydrodynamic hull shape with balancing the trade-off between computational cost and fluid dynamic fidelity. An AUV hull form has been optimised to obtain low resistance hull. Hydrodynamic optimisation of hull form has been carried out by employing five parametric geometry models with a streamlined constraint. Three Genetic Algorithm optimisation procedures are applied by three simple drag predictions which are based on the potential flow method. The results highlight the effectiveness of considering the proposed hull shape optimisation procedure for the early stage of AUV hull desig
The use of computational fluid dynamics to assess the hull resistance of concept autonomous underwater vehicles
No full textAutonomous Underwater Vehicles (AUV’s) provide an important tool for collecting detailed scientific information from the oceans depths. The hull resistance of an AUV is an important factor in determining the powering requirements and range of the vehicle. This paper discusses the use of Computational Fluid Dynamics (CFD) to determine the hull resistance of three existing AUV’s, of differing shape and size. The predictions are compared with available experimental data and good agreement found. This work has demonstrated that with use of suitable shape parameterisation it is possible to carry out concept design evaluation using a RANS flow solver
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