摘要:

AbstractThe design of a composite laminate involves the determination of layer thicknesses and orientation angles. The problem is posed as the optimum weight (or volume) design of composite laminates which withstand the specified loads without failure. The modified Hill‐Mises or Tsai‐Wu failure criterion is taken as a constraint, each layer being subjected to this criterion. The design variables considered are the layer thicknesses and orientation angles. Based on the finite‐element analysis capability of composite laminates provided by NISA II, a composite laminate optimization procedure has been developed. Nonlinear optimization techniques are used to approach the optimum design of the composite laminates. Efficient design sensitivity analysis procedures are implemented based on the direct differentiation and adjoint variable methods. Example problems illustrate that the program offers an efficient and practical design tool for composite lami

ISSN:1069-8299    

DOI:10.1002/cnm.1640091102

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA simple automatic time‐step control procedure is devised for use in implicit one‐step time‐integration schemes. First‐ and second‐order semi‐discrete systems of equations emanating from finite‐element spatial discretization are considered. The varying time‐step interval is controlled by the relative distance between the solution in two consecutive time steps, using the solution update formula of the time integrator under consideration. A model problem involving the vibrations of a membrane is used to demonstrate the performanc

ISSN:1069-8299    

DOI:10.1002/cnm.1640091103

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractElastic contact between a thick shell of revolution and a rigid plate in the case when the plate is brought into contact with the shell by giving a finite displacement to the plate is analysed by the finite‐element method. Field‐consistent higher‐order strain‐displacement relations with vanishing shear stresses on the surfaces are used. A finite element based on these relations is developed and used for the analysis. The contact conditions are imposed by use of the Lagrangian multipliers method, and the resulting minimization problem is solved iteratively. This procedure will lead to reduced memory requirements and computati

ISSN:1069-8299    

DOI:10.1002/cnm.1640091104

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractAn explicit formulation and a procedure for the computation of isotropic tensor‐valued tensor functions is discussed. The formulation is based on a spectral decomposition in terms of second‐order eigenvalue bases, which avoids the costly computation of eigenvectors. As an important result a compact structure of the fourth‐order derivatives of general second‐order isotropic tensor functions is pr

ISSN:1069-8299    

DOI:10.1002/cnm.1640091105

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractStructural models of large space structures have a substantial number of degrees of freedom (DOF) and possess semi‐positive‐definite stiffness matrices. The paper presents an efficient co‐ordinate reduction procedure for structural dynamic analysis of large space structures. The method is based on the superposition of load‐dependent Ritz vectors, which are computed in block form using a shifted stiffness matrix. Comparative transient dynamic analyses are performed on a 2803 DOF model of the space station Freedom using the load‐dependent method (LDM) and the mode‐displacement method (MDM) based on the superposition of eigenvectors. It is shown that the LDM is able to provide convergence of displacements with a small number of vectors. The acceleration response is found to be more sensitive to vector truncation than the displacement response. Error norms based on the representation of the dynamic load by the vector basis are developed to provide an indication of the effect of vector truncation on the structur

ISSN:1069-8299    

DOI:10.1002/cnm.1640091106

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractBoundary integral equations are generally derived by employing a Cauchy Principal Value definition for the singular integral involving the derivative of the Green function. As a consequence, evaluation of this integral requires special attention, and computing the associated ‘solid angle coefficient’ can often pose difficulties. As discussed herein, these problems can be avoided by defining the integral directly, in terms of a limit to the boundary. This approach leads to a straightforward evaluation proced

ISSN:1069-8299    

DOI:10.1002/cnm.1640091107

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe reduction of stress concentration around a circular hole in a dynamically loaded plate by introducing auxiliary holes around the original hole is studied numerically. The solution of this plane stress problem is carried out in the Laplace transformed domain with the aid of the boundary‐element method, and subsequently the time domain response is obtained by numerically inverting the transformed solution. Numerical examples are presented which demonstrate a stress reduction as high as 18 per pent by the introduction of two auxiliary holes in the loading direction for the uniaxial cas

ISSN:1069-8299    

DOI:10.1002/cnm.1640091108

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThree strain recovery techniques are investigated in the framework of the mixed iterative method. The need for appropriate strain recovery for low‐order elements is shown. The three techniques compared are: C‐lumping, strain‐smoothing and a new technique called C‐splitting. It is shown that the use of C‐lumping has negative effects on the convergence of the mixed iterative method. Both strain‐smoothing and C‐splitting deliver convergent results, but the new technique con

ISSN:1069-8299    

DOI:10.1002/cnm.1640091109

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:1069-8299    

DOI:10.1002/cnm.1640091110

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:1069-8299    

DOI:10.1002/cnm.1640091101

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY