Showing papers by "George I. N. Rozvany published in 1991"

Applications of the COC Algorithm in Layout Optimization

Abstract: Whilst the advantages of iterative continuum-based optimality criteria (COC) methods in cross-section optimization (“sizing”) were discussed elsewhere (e.g. [4, 5]), this paper is devoted to applications of the above technique in layout optimization. Earlier studies of the latter field by others used a two-stage process consisting of separate topological and geometrical optimization and considered only a very small number of members. It will be shown here that the COC algorithm achieves a simultaneous optimization of the topology and geometry in layout problems with many thousand potential members. Moreover, some observations on shape optimization by the “homogenization” method are offered and an alternative approach to global shape optimization is suggested.

A note on truss design for stress and displacement constraints by optimality criteria methods

Abstract: One of the difficulties with the optimization of large structural systems by optimality criteria (OC) methods, in which stress constraints are stated in terms of relative displacements, is the need to evaluate a large number of Lagrangians. An improved OC method, which does not require Lagrangians for stress constraints, is outlined in this note in the context of problems with stress constraints and a single displacement constraint. Whilst general formulae giving continuum-type optimality criteria for elastic systems are available (e.g. Rozvany 1989), the criteria for trusses are confirmed here by a simple derivation and verified on a ten-bar truss, for which the proposed technique and a dual programming method are shown to give a twelve-digit agreement.