摘要:

AbstractA brief review of the structural optimization literature and a description of the present status of optimization methods are presented. The scope of the review is limited and does not profess to cover the entire literature.Results of the optimization of two structures (by the optimality criteria approach) are presented. There are some conclusions and recommendations for future developments in structural optimization.

ISSN:0029-5981    

DOI:10.1002/nme.1620130202

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractPrestressed concrete members, because of the use of high strength materials and the efficient disposition of tensile forces, need considerably less material. This and other advantages, however, are offset by the high unit costs of materials and the associated specialized labour. Thus, it is important to make the most of the savings in materials through the application of optimum design procedure. Among the available optimization techniques, generalized geometric progamming (GGP) is ideally suited because the design equations of prestressed concrete members are expressible in the form of polynomials. Using the GGP, in this study, a set of minimum prestress force designs are obtained for various depths of one‐way slab. From the data thus obtained a minimum cost design procedure is explained. Moreover, the need for supplementary non‐prestressed reinforcement to obtain economical designs for depths of slab beyond a certain depth is also sh

ISSN:0029-5981    

DOI:10.1002/nme.1620130203

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe problem of optimal design of the shape of a free or internal boundary of a body is formulated by assuming the boundary shape is described by a set of prescribed shape functions and a set of shape parameters. The optimzation procedure is reduced to determination of these paramenters. For constant volume or material cost constraint, the optimality conditions are derived for the case of mean complicance design of elastic structures of a non‐linear material. Some additional conditions for the global minimum of the mean compliance are proved. The most typical cases of boundary variations are discussed. The optimal shape problem is next formulated by means of the finite element method and the iterative solution algorithm is discussed by using the optimalitycriteria. Several simple numerical examples are include

ISSN:0029-5981    

DOI:10.1002/nme.1620130204

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe problem of the axial vibration of a cantilever beam is investigated both analytically and numerically. The mass distribution that minimizes the total mass for a given value of the frequency parameter β is determined using both the sequential ordinary gradient‐restoration algorithm (SOGRA) and the modified quasilinearization algorithm (MQA). Concerning the minimum value of the mass, SOGRA leads to a solution precise to at least 4 significant digits and MQA leads to a solution precise to at least 6 significant digits.Comparison of the optimal beam (a variable‐section beam) with a reference beam (a constant‐section beam) shows that the weight reduction depends strongly on the frequency parameter β. This weight reduction is negligible for β → 0, is 11.3 per cent for β = 1, is 55.3 per cent for β = 1.4, and approaches 100 per cent

ISSN:0029-5981    

DOI:10.1002/nme.1620130205

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe paper presents a finite element method for minimum weight design of structures with lower‐bound constraints on the natural frequencies, and upper and lower bounds on the design variables.The design algorithm is essentially an iterative solution of the Kuhn‐Tucker optimatility criterion. The three most important features of the algorithm are: (i) a‐small number of design iterations are needed to reach optimal or near‐optimal design, (ii) structural elements with a wide variety of size‐stiffness may be used. The only significant restriction is the exclusion of curved beam and shell elements, (iii) the algorithm will for multiple as well as single frequency constraints.The design procedure is illustrated with three simple

ISSN:0029-5981    

DOI:10.1002/nme.1620130206

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThis paper considers the problem of solving the optimality criteria equations for a truss structure. A unique Newton‐Raphson method for optimizing redundant structures subject to multiple constrainsts on displacement and member sizes is presented. Both equality and inequality constraints are considered. The characteristics of this approach along with least squares and recursive techniques for the solution of the non‐linear optimality criteria equations are examined numerically for several sample problems. This new formulation offers the advantages of a reduction in the number of dependent variables, ease of incorporation of various types of constraints, and very rapid converge

ISSN:0029-5981    

DOI:10.1002/nme.1620130207

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThis paper treats shape optimal design of two‐dimensional structures. Sensitivity of cost and constraint functions to changes in the shape of the structure are obtained by applying theorems from the calculus of variations and by using consistent first‐order approximations of functions arising in an optimal design problem. A generalized steepest descent algorithm is presented for determination of the optimum shape. The method is applied to a load carrying shear plate that models a component of the high pressure seal in a gun launched high velocity project

ISSN:0029-5981    

DOI:10.1002/nme.1620130208

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractStructural optimization problems with constraints imposed on natural frequencies are studied, giving special attention to the inherent non‐linearity of natural frequency constraints. Assuming that the system mass and stifiness matrices are expressed as linear functions of the design variables, it is shown that there are two sources of non‐linearity for natural frequencies in such a design space. Furthermore, simple variable transformation does not alleviate these non‐linearities as it does in the static response case. Recognizing the inherent non‐linear characteristics of natural frequency constraints, a second order Taylor series approximation for each eigenvalue of the equations of motion is derived and applied successfully to improve stability and overall efficiency of the automated synthesis

ISSN:0029-5981    

DOI:10.1002/nme.1620130209

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe method of optimality criterion and recursion precedure is employed for the design of braced and unbraced structural systems subject to various static and dynamic forces. The dynamic excitations can be applied forces, ground motions, or the equivalent seismic forces of the Uniform building Code (UBC). By using a sophisticated computer program developed, it has been found that: (1) for a set of given loads and constraints, the optimum braced system is lighter than an unbraced system, (2) the use of the natural period recommended by the code in the design yields lighter structure than that based on the period of eigensolution, (3) for seismic structural design, three to five fundamental modes are needed for adequate accuracy, and theP‐Δ effect, due to vertical ground motion and the gravity load, must be considerded because it demands heavier structural design, (4) the code does not provide an adequate structural design as the actual earthquake response spectrum requires, and (5) the interaction of three‐dimensional earthquake motions can significantly influence an optimum design and is currently under investiga

ISSN:0029-5981    

DOI:10.1002/nme.1620130210

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractDerivation of an optimality criterion for finite element structural representations using constant‐moment plate‐bending triangular elements ispresented. Numerical examples of minimum‐mass design of both simply‐supported and clamped elastic plates for concentrated and distributed loading conditions under a single displacement constraint serve to illustrate the suggested procedure. Interpretation of the solution obtained and difficulties involved are discussed in the light of recent application of optimal control theory to structural optim

ISSN:0029-5981    

DOI:10.1002/nme.1620130211

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY