摘要:

AbstractThe paper addresses the performance of square elements of typeQ(p) andQ′(p). (Q(p) andQ′(p) are elements of degreep, analogous to the well‐known 9‐ and 8‐noded elements forp= 2.) The performance is analysed theoretically for the class of analytic functions. Numerical experiments confirm the conclusions drawn from the theory. The computational complexity of a solution algorithm is studied using timings of the computation on an Alliant FX/8 computer. The data show that high‐order elements are very effective for the considered class o

ISSN:0029-5981    

DOI:10.1002/nme.1620361502

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA unified approach is presented for establishing exact integration of the constitutive equations in elastoplasticity, assuming the total strain‐rate direction to be constant. This unified approach includes all previous exact integration procedures as special cases and, in addition, some new closed‐form solutions are derived for combined kinematic and isotropic hardening. Special emphasis is laid on combined kinematic and isotropic hardening for von Mises' material and on isotropic hardening for Mohr‐Coulomb and Tresca mate

ISSN:0029-5981    

DOI:10.1002/nme.1620361503

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe rigid‐ice model of frost heave is one of the most comprehensive frost‐heave models but is restricted to one‐dimensional cases in its present form. In this paper, the model is extended to two‐dimensional problems. The complete formulation of the partial differential equations governing heat, moisture and ice transport in freezing soils is provided. The equations are subsequently solved using the Galerkin finite element method in space and the finite difference method in time. A computer program is developed for the two‐dimensional rigid‐ice model. A case of freezing around chilled gas pipeline is solved and the numerical results are compared with experimental values, with good agreement between the two sets

ISSN:0029-5981    

DOI:10.1002/nme.1620361504

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA three‐dimensional dynamic infinite element which satisfies the following requirements: (1) displacement compatibility on the interface between finite and infinite elements; (2) definition of the wave propagation and amplitude attenuation behaviours in the infinite element using wave propagation functions; (3) convergence of the generalized integrals related to mass and stiffness matrices of the infinite element: and (4) displacement continuity along the common boundary of neighbouring infinite elements in the case of simulating multiple material layers or multiple wave numbers within the foundation, is presented in this paper. Since P‐waves, S‐waves and R‐waves in the foundation can be simulated Simultaneously in the present infinite element, the seismic response of an arch‐dam‐foundation system, especially a thin double‐curvature arch‐dam‐foundation system where the boundary element loses its competitive capacity with the finite element, can be economically calculated by coupling this infinite element with conventional finite elements. The good accuracy obtained using the present infinite element and finite element coupling model to simulate foundation wave problems has been proven by comparing the current numerical results with previous a

ISSN:0029-5981    

DOI:10.1002/nme.1620361505

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA novel technique is presented for the control of mapped quadrilateral and hexahedral meshes generated inside a collection of connected subregions. Target division numbers on the subregion edges are given as input. By allowing these numbers to vary, meshes can be found which satisfy both the subregion constraints imposed by the mesh patterns being employed, and the compatibility constraints on edges shared by two or more adjacent subregions. Among all such feasible solutions the optimal one is obtained by minimizing the changes to the division numbers, using an integer programming technique.

ISSN:0029-5981    

DOI:10.1002/nme.1620361506

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractNumerical integration of stiff first‐order systems of differential equations is considered. It is shown how aC0‐continuous polynomial time discretization, in conjunction with a weighted residual method, can be used to derive methods corresponding to the diagonal and first subdiagonal Padé approximants. In this manner A ‐stable schemes of order 2kandL‐stable schemes of order 2k‐lare obtained, at least fork⩽ 4. The methods are hierarchical in the sense that a scheme with a given accuracy embraces the equations of all lower‐order methods that have the same stability type. We show how this feature may be utilized to perform partial refinements in the integration process, and how an error estimation by an embedding approach naturally follows. An adaptive algorithm based on the error estimator is suggested. Some numerical experiments that illustrate the idea

ISSN:0029-5981    

DOI:10.1002/nme.1620361507

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA new boundary element solution algorithm for two‐dimensional and axisymmetric contact problems with friction, based on an independent discretization of the contacting surfaces and under static and proportional loading conditions, is presented. The solution procedure uses the element shape functions to distribute the geometry, tractions and displacements on each contact element. The contact constraints are then applied between each contacting node and the opposite contact segment. The overall boundary element matrix equations for the contacting bodies are coupled using the contact conditions at the interface without introducing any additional variables into the solution matrix. The algorithm is applied to several two‐dimensional and axisymmetric frictional contact examples and the results obtained are in very good agreement with finite element and analytical soluti

ISSN:0029-5981    

DOI:10.1002/nme.1620361508

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe paper presented here reviews the numerical techniques used currently to calculate the singular integrals and nearly singular integrals in the boundary element analysis. Some incorrect algorithms published before are discussed and a new numerical technique to calculate the nearly singular integral is developed. The numerical results show a significant improvement in both accuracy and efficiency compared to the traditional adaptive Gaussian quadrature and subdivision techniques.

ISSN:0029-5981    

DOI:10.1002/nme.1620361509

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe sequential linear programming (SLP) method is one of the easiest optimization techniques used to treat non‐linear optimization problems. The successful application of the method is based on the proper choice of the move limits, which are unfortunately uncertain in the SLP algorithm. To enhance the efficiency and reliability of the SLP algorithm, six methods are proposed to calculate the move limits. The first three methods use the constraint equations to compute the minimum variations needed from the current design point to reach the constraint boundaries. The fourth method incorporates the cost function information as well as the constraints to figure out the move limits. The last two methods form a quadratic programming (QP) subproblem and solve for the change of the quadratic cost function. The move limits used in SLP are then computed from the estimated change of the linear cost function from the QP solution. Four numerical examples are employed to demonstrate the solution process by the methods proposed. The advantages and disadvantages of these methods are discusse

ISSN:0029-5981    

DOI:10.1002/nme.1620361510

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:0029-5981    

DOI:10.1002/nme.1620361511

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY