ISSN:0029-5981    

DOI:10.1002/nme.1620121202

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractIn this paper, the application of a particular class of computational methods, the alternating direction implicit methods applied to the solution of time dependent heat conduction problems in regions involving circular symmetry is presented.

ISSN:0029-5981    

DOI:10.1002/nme.1620121203

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe stream function‐vorticity method for solving Navier‐Stokes equations with finite elements is often disregarded in view of the necessity of an iterative proceudre for satisfying the boundary conditions. The present work shows briefly that such iterations are unnecessary. Sample solutions for flows in a square cavity and in a channel with a step show good agreement with existing soluti

ISSN:0029-5981    

DOI:10.1002/nme.1620121204

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe present paper describes a hybrid stress finite element formulation for geometrically non‐linear analysis of thin shell structures. The element properties are derived from an incremental form of Hellinger‐Reissner's variational principle in which all quantities are referred to the current configuration of the shell. From this multi‐field variational principle, a hybrid stress finite element model is derived using standard matrix notation. Very simple flat triangular and quadrilateral elements are employed in the present study. The resulting non‐linear equations are solved by applying the load in finite increments and restoring equilibrium by Newton‐Raphson iteratioin. Numerical examples presented in the paper include complete snap‐through buckling of cylindrical and spherical shells. It turns out that the present procedure is computationally efficient and accurate for non‐linear shell problems of hi

ISSN:0029-5981    

DOI:10.1002/nme.1620121205

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractA common method for numerically approximating two‐point parabolic boundary value problems of the formut=L[u]+f(u) defined of the semi‐infinite strip S = [0, 1]×[0, ∞]is to first discretize the spatial operator in the differential equation and then solve for the time evolution. Such an approach typically involves solving a system of algebriaic equations at a sequence of time steps. In this paper we take a different approach and subdivideSinto a collection of semi‐infinite substripsSi= [xi, xi+1]×[0, ∞], and use blending function techniques to derive finite parameter functionsei(x, t) defined onSi. Spectral matching methods are used in derivingeito ensure that (u −ei) can be made small onSi. Galerkin's method, with associated integration sover the entire space‐time domainS, is then used to generate approximations tou(x, t) based upon the so defined infinite element (ei, Si). Approximations are hence found for all (x, t) inSby solving one well structed system of algebraic equations. We apply the method to several linear and non

ISSN:0029-5981    

DOI:10.1002/nme.1620121206

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractIn this paper a technique previously developed for the analysis of rigid‐plastic structural frames is adapted to provide a formal procedure for finding the limit load of any structure formed from rigid blocks. In this procedure the load factor is maximized subject to the euilibrium equations of the structure and linear constraints imposed by criteria of failure at the block interfaces.In part I of the paper it is assumed that the limiting shear force associated with sliding at a block interface is independent of the normal component of force across the interface. This assumption means that the normality rule is satisfied, so that the upper‐ and lower‐bound theorems of classical limit analysis apply. This part includes a description of computer program for the collapse analysis of masonry arches with joints incapable of carrying tension.In part II the limit on the Shear force at a block interface is assumed to be that associated with Coulomb friction. It is not difficult to extend the computational algorithm described in part I to deal with this situation. However, the failure mechanism computed by the algorithm will not necessarily satisfy the normality rule. The corresponding limit load may therefore be an over‐estimate of the true failure load, even though it is computed by a lower‐bound (equilibrium) approach. A criterion is established for testing the validity of a failure load computed in these circ

ISSN:0029-5981    

DOI:10.1002/nme.1620121207

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractA new and a simple algorithm for approximate calculation of optimal output‐constrained feedback regulators is presented. computational simplicity is achieved by using properties of weakly coupled linear systems. The algorithm has been shown to be very effective in solving high dimensional control problem

ISSN:0029-5981    

DOI:10.1002/nme.1620121208

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

ISSN:0029-5981    

DOI:10.1002/nme.1620121209

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

ISSN:0029-5981    

DOI:10.1002/nme.1620121210

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractSymmetric three point quadrature schemes are at present available for triangles for exact integration of polynomials of degree 2. There are other possible symmetries, which provide higher accuracies. Exact integration of polynomials of a higher degree is possible. General formulations are made and a set of three integration points for improved accuracy is given.

ISSN:0029-5981    

DOI:10.1002/nme.1620121211

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY