Browsing by Author "Akay, H. U."

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Citation - Scopus: 1
Improved Parallel Preconditioners for Multidisciplinary Topology Optimisations
(Taylor & Francis Ltd, 2016) Akay, H. U.; Oktay, E.; Manguoglu, M.; Sivas, A. A.
Two commonly used preconditioners were evaluated for parallel solution of linear systems of equations with high condition numbers. The test cases were derived from topology optimisation applications in multiple disciplines, where the material distribution finite element methods were used. Because in this optimisation method, the equations rapidly become ill-conditioned due to disappearance of large number of elements from the design space as the optimisations progresses, it is shown that the choice for a suitable preconditioner becomes very crucial. In an earlier work the conjugate gradient (CG) method with a Block-Jacobi preconditioner was used, in which the number of CG iterations increased rapidly with the increasing number processors. Consequently, the parallel scalability of the method deteriorated fast due to the increasing loss of interprocessor information among the increased number of processors. By replacing the Block-Jacobi preconditioner with a sparse approximate inverse preconditioner, it is shown that the number of iterations to converge became independent of the number of processors. Therefore, the parallel scalability is improved.
Citation - WoS: 46
Citation - Scopus: 54
Parallelized Structural Topology Optimization and Cfd Coupling for Design of Aircraft Wing Structures
(Pergamon-elsevier Science Ltd, 2011) Oktay, E.; Akay, H. U.; Merttopcuoglu, O.
A set of structural optimization tools are presented for topology optimization of aircraft wing structures coupled with Computational Fluid Dynamics (CFD) analyses. The topology optimization tool used for design is the material distribution technique. Because reducing the weight requires numerous calculations, the CFD and structural optimization codes are parallelized and coupled via a code/mesh coupling scheme. In this study, the algorithms used and the results obtained are presented for topology design of a wing cross-section under a given critical aerodynamic loading and two different spar positions to determine the optimum rib topology. (C) 2011 Elsevier Ltd. All rights reserved.