摘要:

AbstractAn iterative method is introduced for computing second‐order partial derivatives (sensitivities) of eigenvalues and eigenvectors of matrices which depend on a number of real design parameters. Numerical tests confirm the viability of the method and support our theoretical analysis. Alternative methods are reviewed briefly and compared with the one proposed her

ISSN:1069-8299    

DOI:10.1002/cnm.1640100102

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractIn the formulation of the semi‐Loof element the rotation of the tangent plane is derived from the interpolation of the transverse displacement, while the rotation of the normal is interpolated separately by another set of shape functions. The geometric stiffness matrix can be formulated by use of either of the two rotation representations. It is demonstrated that the use of the tangent plane representation in the geometric stiffness matrix is far superior to the common form at presen

ISSN:1069-8299    

DOI:10.1002/cnm.1640100103

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractAn efficient solution to boundary‐value problems may be based on the application of a suitably truncated T‐complete set of Trefftz functions over individual subdomains and on linking the fields by a least‐squares procedure. Although it yields a symmetric system of linear equations, this approach as originally presented by Zielinski and Zienkiewicz is not suited for implementation into FE codes. The present paper presents two equivalent formulations, which take respectively the form of the finite (FE) and non‐conventional boundary‐element (BE) approach. Both allow the resulting simultaneous equations to be assembled following the standard direct stiffness methods and can readily be implemented into existing FE codes.As in the conventional p‐method, the accuracy may be controlled within large limits without increasing the number of elements. The present approach allows substantial saving in computer time in comparison with the so‐called hybrid‐Trefftz (HT) elements, though the assumed displacement fields are identical. The practical efficiency of the new T‐element approach is assessed on the problem of stress concentration in a symmetrically compressed

ISSN:1069-8299    

DOI:10.1002/cnm.1640100104

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractReduction of reheating time saves on energy input and increases the production rate in the steel‐making process. Reductions can be achieved by allowing the centre temperature of a steel bar to be lower than the surface temperature by a small margin, before starting with the hot rolling process. This can only be done if the temperature difference does not adversely affect the quality of the final product or the rolling equipment. The paper presents numerical simulations to investigate the savings that can be obtained for various temperature differences between surface and centre temperatures to evaluate the feasibility of the concept. The results presented include the cross‐sectional temperature distribution in a typical steel bar during reheating at hourly intervals as well as the effect of various differences between centre and surface temperatures on reheating time. The reheating time predicted for various steel bar sizes as well as for various differences between surface and centre temperatures are then compared against measured reheating times. To indicate the practical applicability of the concept to the hot rolling process the detailed temperature distribution in a typical steel bar, with an initial temperature difference between the surface and centre of the bar, was simulated numerically. This was compared to a similar simulation for a well soaked steel bar for which experimental measurements are also available. The numerical method used to obtain the simulations is also presented. Boundary conditions account for radiation, convection and conduction inside the steel bar. It is concluded that the concept of allowing differences between surface and centre temperatures of a steel bar during reheating holds great potential for energy savings in the steel‐making pr

ISSN:1069-8299    

DOI:10.1002/cnm.1640100105

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractA method is presented for the solution of elliptical problems defined on general‐shape multiconnected three‐dimensional domains approximated by means of polyhedra. The boundary conditions may be of the Neumann type. The differential operator and the normal derivative are discretized by generalized finite‐difference (GFD) methods using an orthogonal non‐uniform Cartesian grid. The convergence properties are analysed and the solutions of some Poisson and biharmonic problem are pr

ISSN:1069-8299    

DOI:10.1002/cnm.1640100106

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractA heuristic optimization design methodology based on redesign rules for composite laminated plates is presented. It is modelled on the cyclic approach to the design process observed in designers of structural components using composites. In comparison with a simple weight minimization algorithm it gives quasioptimal ply thicknesses, but takes under ten iterations. It is thereby shown to be most suitable for initial design studies. Multiaxial combinations of in‐plane loads and bending moments are considered in the design procedur

ISSN:1069-8299    

DOI:10.1002/cnm.1640100107

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractIn this paper, an iterative method of statistic linearization (IMSL) is presented to solve non‐linear stochastic vibration equations. This method represents an improvement over the classical linearization method. The method uses the solution of the corresponding linear vibration equation as an initial value in an iterative procedure. To obtain information about essential statistical average values, the method uses a ‘boot‐strapping’ procedure, which defines a pseudorandom process based on the statistical characteristics of the linear solution and then uses samples from the process to estimate them. For Gaussian input excitation, the statistical average values are obtained by theoretical a

ISSN:1069-8299    

DOI:10.1002/cnm.1640100108

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractStandard isoparametric finite elements can be used as singular crack‐tip elements in fracture mechanical computations by placing the middle nodes in the neighbourhood of the crack tip. Such elements have already been applied to several plane and three‐dimensional problems, so this method can be considered as commonly well accepted. The paper shows that singularity of orderr(1 − m)/mis obtained with annth‐order isoparametric

ISSN:1069-8299    

DOI:10.1002/cnm.1640100109

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractDynamic stress intensity factors of cracked linear viscolastic solids under conditions of plane stress are computed by the boundary‐element method in conjunction with the numerical Laplace transform and the correspondence principle of linear viscoelasticity. Quadratic isoparametric conventional and quarter‐point boundary elements are employed. The multidomain approach is used in cases where symmetry cannot be invoked. Dynamic stress intensity factors are computed for cracked viscoelastic rectangular plates subjected to suddenly applied loads, and comparisons are made against results obtained by other numerical meth

ISSN:1069-8299    

DOI:10.1002/cnm.1640100110

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

ISSN:1069-8299    

DOI:10.1002/cnm.1640100111

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY