摘要:

AbstractBased on a refined third‐order shear deformation plate theory recently proposed by the author, a three‐node, fully conforming, multilayered anisotropic plate element of arbitrary triangular shape is developed in this paper. The element incorporates 10 nodal d.o.f., namely the two in‐plane displacements, the two shear rotations, the transverse displacement and its first and second derivatives, thus giving a total of 30 d.o.f. The formulation includes extension, bending and transverse shear deformation states; moreover, it fulfilsa priorithe geometric and stress continuity conditions at the interfaces, and it requires only five generalized displacements to describe the kinematics of the plate deformation. The formulated plate element is assessed for its performance comparing its predictions either with exact solutions from the plate model or with other approximate two‐dimensional so

ISSN:0029-5981    

DOI:10.1002/nme.1620380102

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe paper presents an algorithm for the solution of problems that are discretized partly by the finite element method and partly by the boundary element method. The algorithm is based on the conjugate gradient method with preconditioning by an auxiliary conjugate projector that reduces the iterations to the interface. A numerical example is presented to illustrate the performance of the algorithm. The method may prove useful also in parallel environment.

ISSN:0029-5981    

DOI:10.1002/nme.1620380103

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractAn extremal principle is formulated for the linear viscoelastic problem with general viscous kernel. This is an extension of the classical total potential energy principle of the linear elasticity. Then a discretized formulation in space and time is shown for frame structures, using finite element technique. Several numerical examples, for two different kinds of viscoelastic materials, testify the accuracy and reliability of the proposed method. The matrix conditioning indexes obtained are compared with those achieved by applying the least square method.

ISSN:0029-5981    

DOI:10.1002/nme.1620380104

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe aim of this work is to calculate the optimum history of boundary cooling conditions that, in two‐dimensional conduction driven solidification processes, results in a desired history of the freezing interface location/motion. The freezing front velocity and heat flux on the solid side of the front, define the obtained solidification microstructure that can be selected such that desired macroscopic mechanical properties and soundness of the final cast product are achieved.The so‐called two‐dimensional inverse Stefan design problem is formulated as an infinite‐dimensional minimization problem. The adjoint method is developed in conjunction with the conjugate gradient method for the solution of this minimization problem. The sensitivity and adjoint equations are derived in a moving domain. The gradient of the cost functional is obtained by solving the adjoint equations backward in time. The sensitivity equations are solved forward in time to compute the optimal step size for the gradient method. Two‐dimensional numerical examples are analysed to demonstrate the performance of the prese

ISSN:0029-5981    

DOI:10.1002/nme.1620380105

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractA finite element formulation is developed to determine the order and angular variation of singular stress states at material and geometric discontinuities in anisotropic materials subject to antiplane shear loading. The displacement field of the sectorial element is quadratic in the angular co‐ordinate direction and asymptotic in the radial direction measured from the singular point. The formulation of Yamada and Okumura14for in‐plane problems is adapted for this purpose. The simplicity and accuracy of the formulation are demonstrated by comparison to several analytical antiplane shear solutions for both isotropic and anisotropic multi‐material wedges and junctions with and without disbonds. The nature and speed of convergence of the eigensolution suggests that the solution presented here could be used in developing enriched elements for accurate and computationally efficient evaluation of stress intensity factors in problems having complex global geome

ISSN:0029-5981    

DOI:10.1002/nme.1620380106

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThis paper presents a method for generating tetrahedral meshes in three‐dimensional primitives. Given a set of closed and convex polyhedra having non‐zero volume and some mesh controlling parameters, the polyhedra are automatically split to tetrahedra satisfying the criteria of standard finite element meshes. The algorithm tries to generate elements close to regular tetrahedra by maximizing locally the minimum solid angles associated to a set of a few neighbouring tetrahedra. The input parameters define the size of the tetrahedra and they can be used to increase or decrease the discretization locally. All the new nodes, which are not needed to describe the geometry, are generated automatica

ISSN:0029-5981    

DOI:10.1002/nme.1620380107

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractA parameter study involving a feasibility factor, adaptive tolerance refinement and active set and move limits is conducted on the interior feasible direction method with successive approximations (SAM). The study involves the sizing design of five structural problems of which one is a large power transmission tower to be designed in adherence with a standard design code. It is concluded that a move limit is dispensable for this application while adaptive tolerance refinement makes the algorithm more efficient. Optimal ranges for the feasibility factor and active set limits are suggested. This study reaffirms and quantifies the exceptional stability and robustness of the SAM algorithm.

ISSN:0029-5981    

DOI:10.1002/nme.1620380108

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe physical problem considered in this paper is that of a non‐linear elastic body being indented by a rigid punch. The treatment is based on finite element discretization and sequential quadratic programming (SQP). The finite element formulation is obtained through a variational formulation, which generalizes to frictionless contact a three‐field principle which involves deformation, volume strain and hydrostatic pressure as independent fields. We compare an incremental load method and a method where the indentation for the final load is sought directly. Crucial for the second method is the use of a line search with respect to a merit function which measures the infeasibility in the optimality criteria for the problem; this line search also includes a check of the orientation‐preserving condition of a positive determinant of the deformation gradient. Each iteration within an SQP method requires the solution of a quadratic programming (QP) subproblem, and four different methods for the solution of these subproblems are compared. The performance of the overall procedure is also compared to that of a commercially available system. Test examples ranging from 23 to 770 displacement degrees of freedom are treated. The computational results show that the proposed solution concept is feasible and efficient. Furthermore, it can be applied to general non‐linear elastic contact problems, since it does not include anyad h

ISSN:0029-5981    

DOI:10.1002/nme.1620380109

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

ISSN:0029-5981    

DOI:10.1002/nme.1620380110

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

ISSN:0029-5981    

DOI:10.1002/nme.1620380111

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY