摘要:

AbstractA shear panel element of general quadrilateral shape is so formulated that it assumes a state of constant shear flow. This is achieved by using isoparametric shape functions to approximate the displacement field and then using the mean of the strain‐displacement matrix to evaluate shear strain and the resulting stiffness matrix. Numerical examples show that the element reproduces analytical solutions when its shape is rectangular and behaves satisfactorily when its shape is not rectangula

ISSN:0748-8025    

DOI:10.1002/cnm.1630080102

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractA method is given which can be used for finding approximate solutions to problems in linear elasticity. It is an extension of the use of an extremum principle mentioned by Prager and Synge1involving both the stresses and the strains. By using this principle Hooke's Law can be approximately imposed on statically admissible stress fields and kinematically admissible strain fields which contain adjustable parameters. The extension uses the same extremum principle to impose approximately the symmetry of the stress tensor as well. This allows the use of a vector stress function, applicable to 2D and 3D problems, which, while ensuring that the equations of force equilibrium are satisfied, does not impose the symmetry of the stress tensor.A mixed finite‐element formulation is developed with the displacement vector and a vector stress function as nodal variables. A simple 2D finite‐element program is described which implements this method and an example of its use is discussed. Advantages over some existing mixed formulations are: it allows permissible stress jumps across a surface; the global matrix is symmetric and positive‐definite; onlyC0continuity is needed between the elements for both types of var

ISSN:0748-8025    

DOI:10.1002/cnm.1630080103

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe paper addresses the problem of plate modelling within the framework of theh–p‐version of the finite‐element method. A natural hierarchy of models is constructed. The lowest member of the hierarchy is the well‐known Reissner–Mindlin model. It is shown that higher degree elements do not show any locking effects for the models under cons

ISSN:0748-8025    

DOI:10.1002/cnm.1630080104

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe mapped infinite element of Zienkiewiczet al.is investigated for three‐dimensional wave scattering applications. The optimal location of the infinite elements as a function of frequency is considered. Near‐field and far‐field convergence are each examined. The results demonstrate that the mapped infinite element is an extremely effective absorbing boundary condition for many applications. In addition, if far‐field accuracy is the desired computational quantity, the infinite elements can be located extremely close to the scatterer surface, significantly reducing the problem dimensi

ISSN:0748-8025    

DOI:10.1002/cnm.1630080105

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

ISSN:0748-8025    

DOI:10.1002/cnm.1630080106

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractNumerical computation of laser beam refraction may involve difficulties associated with ray paths through a caustic, where first‐order amplitude values become infinite. We choose the special test case of a stratified gas, and compare the results obtained by numerical integration of the ray differential equations with both asymptotic results and direct numerical solution of the exact wave equation. A final section evaluates the numerical solution of a parabolic approximation to the Helmholtz equation, with particular reference to the effect of the caustic. The final conclusion is that, with appropriate safeguards, any of these methods can effectively deal with the presence of a caustic surfac

ISSN:0748-8025    

DOI:10.1002/cnm.1630080107

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractAn iterative procedure for calculating eigenvector derivatives has been developed based on the subspace iteration concept. The basic formulation is derived directly from the first variation of the resulting equations of subspace iteration for solving eigenvalue problems. Since the basic formulation conserves the convergence properties of the original subspace iteration for eigen‐problems, an overrelaxation scheme similar to Bathe's approach is employed to accelerate the subspace iteration process for calculating eigenvector derivative

ISSN:0748-8025    

DOI:10.1002/cnm.1630080108

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

ISSN:0748-8025    

DOI:10.1002/cnm.1630080109

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

ISSN:0748-8025    

DOI:10.1002/cnm.1630080101

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY