摘要:

AbstractA recently developed recursive quadratic programming (RQP) algorithm is applied to dynamic response design problems. The algorithm incorporates updated Hessians of the Lagrange function and uses an active set strategy in which only a subset of the constraints is included in the direction finding QP subproblem. Hessian updating with dynamic response constraints presents some difficulties. The primary difficulty is that the total number of constraints and the location of time points where they have to be imposed can change from iteration to iteration. This can cause inconsistencies in Hessian updating if proper numerical procedures are not used. A numerical procedure to handle the situation is developed, implemented and evaluated. Automatic restarting procedures are necessary for proper convergence of the algorithm. The new algorithm is robust as well as more efficient than the purely linear algorithm. The active set strategy plays an important role for application to dynamic response problems. The RQP algorithms that do not use such a strategy are not applicable to this class of problems.

ISSN:0029-5981    

DOI:10.1002/nme.1620241002

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractIn this paper, the effects of selecting initial vectors on computation efficiency for a subspace iteration method are investigated. Four algorithms are used for selecting the initial vectors. First, arbitrary starting iteration vectors are chosen according to Bathe and Wilson's algorithm.1In the other algorithms, the initial vectors are the retrieved eigenvectors from the Guyan and quadratic reduction methods. Improvement of the eigenvalue approximations of the subspace iteration method over reduction methods is presented. The computation effort is examined for the various algorithms used for initial iteration vectors.

ISSN:0029-5981    

DOI:10.1002/nme.1620241003

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractGalerkin's method is applied to random operator equations. Appropriate Hilbert spaces are defined for random functions and solutions are projected into these spaces, allowing the first‐ and second‐moment properties of the solution to be calculated. An equivalent energy‐based approach similar to the Rayleigh–Ritz method is developed, from which a stochastic finite element technique is derived. Several one‐ and two‐dimensional example problems are solved and the result

ISSN:0029-5981    

DOI:10.1002/nme.1620241004

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractSensitivity analysis is presented as a natural addition to interactive multiobjective optimization methods based on compromise programming. It is shown that useful information regarding trade‐offs in the objectives can be generated effectively by means of an analysis of the sensitivity of solutions to variations in preference structures. An implementation based on sequential quadrative programming is provided and examples are given for illustratio

ISSN:0029-5981    

DOI:10.1002/nme.1620241005

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThe problem of interest in this paper is the calculation of the motion of the solid–liquid interface and the time‐dependent temperature field during solidification of a pure metal. An iterative implicit algorithm has been developed for this purpose using the boundary element method (BEM) with time‐dependent Green's functions and convolution integrals.The BEM approach requires discretization of only the surface of the solidifying body. Thus, the numerical method closely follows the physics of the problems and is intuitively very appealing.The formulation and the numerical scheme presented here are general and can be applied to a broad range of moving boundary problems. Emphasis is given to two‐dimensional problems. Comparison with existing semi‐analytical solutions and other numerical solutions from the literature reveals that the method is fast, accurate and without major time step li

ISSN:0029-5981    

DOI:10.1002/nme.1620241006

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThis paper describes how the theorems of structural variation may be used in finite element analysis. The efficiency of the theorems is examined and their application to structural and geotechnical problems illustrated.

ISSN:0029-5981    

DOI:10.1002/nme.1620241007

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractA theory is described which guarantees an upper and lower bound estimate of the discretization error in numerical solutions of elliptic boundary value problems. This method gives bounded global estimates of the error in the energy norm. Pointwise estimates of the error in the solution variable or its derivatives can then be obtained if the numerical solution is exhibiting pointwise monotonic convergence.The versatility of this method is illustrated by its application to numerical solutions from finite element, finite difference and boundary element methods.

ISSN:0029-5981    

DOI:10.1002/nme.1620241008

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThe stiffness matrix is derived for a finite element representing a beam column with rectangular cross section and a single edge crack. The element has zero length, and the standard nodal degrees of freedom associated with beam‐column elements. To illustrate its capabilities, the element is used to model propagation of multiple cracks in a self‐loaded fixed b

ISSN:0029-5981    

DOI:10.1002/nme.1620241009

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractA finite element model suitable for the analysis of column‐supported shells of revolution is presented. This model combines in a single analysis axisymmetric shell elements with nodal circles and column elements with nodal points. Thus, it takes advantage of the axisymmetry of the shell, while the non‐axisymmetric nature of individual columns is fully accounted for. The compatibility between the two different types of elements is achieved through the use of a co‐ordinate transformation. The accuracy of the solutions is demonstrated through numerical examples. When a shell of revolution supported on equispaced columns of the same stiffness is subjected to a harmonically varying load in the circumferential angle, it is found that the resulting displacements are associated with selective harmonic terms. An equation which precisely defines this coupling mechanism is also de

ISSN:0029-5981    

DOI:10.1002/nme.1620241010

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractA new algorithm for self‐adaptive stress analysis is presented. The algorithm is based onh‐convergence and uses the measured stress convergence rate as an error indicator. A theoretical relation between stress convergence rate and pointwise error of stresses is derived for both the 1‐D and 2‐D case. Some examples are presented to illustrate the behaviour of the al

ISSN:0029-5981    

DOI:10.1002/nme.1620241011

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY