摘要:

AbstractA finite difference method for solving mixed initial and boundary value problems governed by hyperbolic partial differential equations is described. The method has been developed specifically to calculate the flow field associated with any arbitrary two‐dimensional or axi‐symmetric body placed in a uniform supersonic stream. In order to preserve accuracy in the neighborhood of the body surface, the equations governing the motion are formulated so that1Streamlines form one system of co‐ordinate curves.2Two of the equations of motion correspond to characteristic relations.The boundary condition at the body is applied by omitting the equation associated with the characteristic curve reaching the body surface from inside. The method presented is a pseudo‐viscous method and flow fields which include shock waves can be treated with ease. The method has been used to calculate the flow past a particular axi‐symmetric waisted body. The shape of this body is such that a secondary internal shock wave is generated by coalescence of Mach lines behind the bow shock wave. The results obtained are compared with theoretical and experimental results obtained by other workers. The investigation has been carried out as part of a programme of work needed to validate the pseudo‐viscous

ISSN:0029-5981    

DOI:10.1002/nme.1620050202

出版商:John Wiley&Sons, Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractIn this paper finite element method for natural vibration problems, based on a modified Rayleigh‐Ritz method is presented. Numerical results of a few simple examples indicate that the method is promisin

ISSN:0029-5981    

DOI:10.1002/nme.1620050203

出版商:John Wiley&Sons, Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractThis paper presents a technique for the optimal design of a large class of structures arising in civil and mechanical engineering. Constraint conditions on stress level, magnitudes of elastic deformation, natural frequency and buckling load are admitted. A computational method is developed, which takes advantage of special features of the structural optimization problem. Numerical examples are solved to illustrate the applicability of the method. These problems are, in themselves, of engineering interest.

ISSN:0029-5981    

DOI:10.1002/nme.1620050204

出版商:John Wiley&Sons, Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractUsing a parametrie representation, it was proved in 19591that the static and kinematic approaches to the plastic collapse problem are dual linear programming problems. In this paper, the generalized parameters used previously are given physical meaning and shown to be readily programmed for computer application. One important advantage of the method is that the equations can be written in general terms such that no assumptions regarding the structural from need to be built into the program. The application is extended to the more general problem of automatic plastic design and it is shown that the inclusion of a serviceability constraint (e.g. no plastic hinges at a given load factor) is trivial in this formulation. The difficult problem of several loading cases is shown to be readily, treated by designing for a given load factor for shakedown rather than plastic collapse. Thought this latter facility, by its dependence on elastic behavior, requires iteration of the stiffness of the structure, repaid convergence appears to be generally obtained. Finally a method is suggested whereby an adequate allowance for frame instability may be made without destroying the linearity of the equations. Thought the equations, as developed, have application to steel framed structures in mind, the extension to the limit design of reinforced concrete structures appears to present no addition complications.

ISSN:0029-5981    

DOI:10.1002/nme.1620050205

出版商:John Wiley&Sons, Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractAn application of the finite element method to inelastic analysis of the Saint‐Venant torsion problem, using a triangular element formulated on the basis of the hybrid stress approach, is described. The stress field in the element is defined by a stress function which is assumed to vary linearly within the element. The warping function on the element boundary is also defined by a linear expression. Numerical results indicate that the method gives an accurate stress solution and is appropriate to the elastic‐plastic analysis of bars of arbitrary cross‐section which may include multiply connected regions. It is further shown that such phenomena as planar orthogonal plastic anisotropy, strain‐hardening and unloading of relevant twisted bar can be treated in a unified

ISSN:0029-5981    

DOI:10.1002/nme.1620050206

出版商:John Wiley&Sons, Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractA displacement method of matrix analysis for local instability of plates, stiffened panels and thin‐walled columns is presented. The analysis is applicable to stiffened panel and columns for which the cross‐section is made up of thin flat plates. For these cases it may be assumed that during buckling deformation no flat component of the cross‐section is translated in its own plane and the edge lines at the junctions between flats remain fixed in space. The analysis leads to the standard eigenvalue equation from which the buckling stress can be determined. The elastic and geometrical stiffness matrices derived for this analysis depend on the wavelength of the buckled pattern and this dependence is of a simple form since all coefficients in the resulting stiffness matrices contain the buckling wavelength only as a common factor allowing for considerable simplification in any numerical computations. With this new formulation of local instability analysis very few elements are required to obtain high accuracy for the buckling stress. Several examples illustrating typical applications of this new method have been inc

ISSN:0029-5981    

DOI:10.1002/nme.1620050207

出版商:John Wiley&Sons, Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractA FORTRAN subroutine name MESHPL is described. This routine generates an alphanumeric image of an arbitrary two‐dimensional finite element mesh on the line printer. This plotting technique can be used for fast on‐line display of nodal points, elements, boundary conditions and loads during the input data preprocessing stage of a finite element analy

ISSN:0029-5981    

DOI:10.1002/nme.1620050208

出版商:John Wiley&Sons, Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractIn finite element displacement methods for vibration and stability problems, upper bounds to eigenvalues are ensured only if consistent and conforming elements arte used, whereas the use of other elements may yield an upper or a lower bound. Here a systematic perturbation of the mass (or geometric stiffness) matrix is used to generate two classes of eigenvalue sequences whose respective members tend to a common limit from opposite sides.

ISSN:0029-5981    

DOI:10.1002/nme.1620050209

出版商:John Wiley&Sons, Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractThe accuracy and convergence properties of two new Timoshenko beam finite elements are compared to those now widely used. Both of the new elements are consistently derived from a variational principle written in terms of the transverse beam deflection and normal rotation. The deflection is expanded as a cubic and the rotation as a quadratic in the axial co‐ordinate of the beam, giving rise to a seven degrees of freedom element. The first element, called TIM7, includes all the degrees of freedom while the second, called TIM4, reduces this number to four through a constraint introduced by Egle. Both elements display monotonic covergence for beam natural frequencies as a function of the number of degrees of freedom and both will give the analyst some measure of confidence in response calculations for beams excited at high frequencie

ISSN:0029-5981    

DOI:10.1002/nme.1620050210

出版商:John Wiley&Sons, Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractThis paper is concerned with the development of a computational algorithm to find the optimal solution to the fluid network distribution design problem. The problem is formulated as a non‐linear mathematical optimization problem and is solved using a sequential unconstrained minimization technique. Illustrative examples are included and the design solutions obtained compared with the solutions obtained using a parametric metho

ISSN:0029-5981    

DOI:10.1002/nme.1620050211

出版商:John Wiley&Sons, Ltd    

年代:1972

数据来源: WILEY