References of "Fleury, Claude"
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See detailScantling Optimization Based on Convex Linearizations and a Dual Approach
Rigo, Philippe ULg; Fleury, Claude ULg

in Marine Structures (2001)

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See detailA family of MMA approximations for structural optimization
Bruyneel, Michaël ULg; Duysinx, Pierre ULg; Fleury, Claude ULg

Conference (2001, July)

This paper deals with the approximation concepts approach applied to structural optimization. In 1987, Svanberg proposed the method of moving asymptotes for solving structural optimization problems. This ... [more ▼]

This paper deals with the approximation concepts approach applied to structural optimization. In 1987, Svanberg proposed the method of moving asymptotes for solving structural optimization problems. This approximation is monotonous and can efficiently treat problems characterized by such a behavior. Svanberg (1995) proposed a modification of the MMA approximation by making it non monotonous. This property is based on an heuristically updated parameter. The resulting approximation is called GCMMA. In Bruyneel et al. (1999), it is shown that it is possible to generate non monotonous GCMMA based approximations, called GBMMA, by using the gradient and/or the function values from previous iteration. It was shown that such approximations improve the convergence speed of the optimization process. In many optimization problems (for example composite structures optimization or simultaneous sizing and optimal configuration of truss structures), the structural responses present both monotonous and non monotonous behaviors. A mixed monotonous/non monotonous approximation scheme has to be used for approximating in the best way the optimization problem (Zhang et al., 1998 and Bruyneel and Fleury, 2000). In this paper, we propose to show that it is possible to derive a very general approximation of the MMA family based on gradients and/or functions values at two successive design step, that present a mixed monotonous/non monotonous behavior. This approximation scheme is based on the GMMA approximation of Dusyinx et al. (1995) and on the non monotonous GBMMA approximations of Bruyneel and Fleury (1999). As the approximation scheme proposed in this paper is general, it contains all the approximations of the MMA family described above, that is MMA, GCMMA, GBMMA and GMMA. According to the characteristics of the problem under consideration, one of those approximations or of a mix of them is used to solve the optimization problem. This selection can be automatic or based on the designer’s knowledge. Numerical applications will show that the derived GMMA/GBMMA approximation scheme is efficient for solving structural optimization problems. Results will be compared with the ones obtained with the other approximations of the MMA family. [less ▲]

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See detailEstimating diagonal second order terms in structural approximations with quasi-Cauchy techniques
Duysinx, Pierre ULg; Nguyen, Van Hien; Bruyneel, Michaël ULg et al

in CHENG, Gen Dong (Ed.) Proceedings of the 4th World Congress of Structural and Multidisciplinary Optimization WCSMO4 (2001, June)

This paper reports preliminary results obtained when estimating diagonal second order terms to be used in structural approximations with the quasi-Cauchy updates which was recently proposed by Zhu ... [more ▼]

This paper reports preliminary results obtained when estimating diagonal second order terms to be used in structural approximations with the quasi-Cauchy updates which was recently proposed by Zhu, Nazareth, and Wolkowicz (SIAM J. of Optimization, 9 (4), 1192-1204, 1999). At first, the theory of quasi-Cauchy updates is presented. Main characteristics of the developments that were necessary to use quasi-Cauchy updates in the context of structural optimization are drawn. The available numerical results allow comparing quasi-Cauchy second order term estimations with other estimation procedures. [less ▲]

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See detailComposite structures design for strength and stiffness with respect to ply thickness and/or fibers orientation
Bruyneel, Michaël ULg; Duysinx, Pierre ULg; Fleury, Claude ULg

in CHENG, Gen Dong (Ed.) Proceedings of the 4th World Congress of Structural and Multidisciplinary Optimization WCSMO4 (2001, June)

This paper presents an optimization approach that allows the design of composite structures under stiffness and strength criteria, with fibers orientations and plies thickness taken into account in the ... [more ▼]

This paper presents an optimization approach that allows the design of composite structures under stiffness and strength criteria, with fibers orientations and plies thickness taken into account in the same optimization loop. The approach is based on the sequential convex programming. An industrial application is presented. [less ▲]

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See detailAn improved weighting method with multibounds formulation and convex programming for multicriteria structural optimization
Zhang, W. H.; Domaszewski, M.; Fleury, Claude ULg

in International Journal for Numerical Methods in Engineering (2001), 52(9), 889-902

This paper presents an improved weighting method for multicriteria structural optimization. By introducing artificial design variables, here called as multibounds formulation (MBF), we demonstrate ... [more ▼]

This paper presents an improved weighting method for multicriteria structural optimization. By introducing artificial design variables, here called as multibounds formulation (MBF), we demonstrate mathematically that the weighting combination of criteria can be transformed into a simplified problem with a linear objective function. This is a unified formulation for one criterion and multicriteria problems. Due to the uncoupling of involved criteria after the transformation, the extension and the adaptation of monotonic approximation-based convex programming methods such as the convex linearization (CONLIN) or the method of moving asymptotes (MMA)are made possible to solve multicriteria problems as efficiently as for one criterion problems. In this work, a multicriteria optimization tool is developed by integrating the multibounds formulation with the CONLIN optimizer and the ABAQUS finite element analysis system. Some numerical examples are taken into account to show the efficiency of this approach. [less ▲]

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See detailReliable Approximation Schemes for Composite Structures Optimization"
Bruyneel, Michaël ULg; Vermaut, O.; Fleury, Claude ULg

in Van Keer, R.; Verhegghe, B.; Hogge, M. (Eds.) et al ACOMEN ’98 : an international conference on advanced computational methods in engineering : Ghent, 2-4 september 1998 (1998, September)

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See detailEnhanced Approximation Schemes for Classical Optimization Algorithm
Bruyneel, Michaël ULg; Vermaut, O.; Duysinx, Pierre ULg et al

Report (1998)

The report assesses the capabilities of the algorithms CONLIN, MDQA, an GCM available in Boss Quattro to solve composite structure optimization. The algorithms are evaluated with respect to the ... [more ▼]

The report assesses the capabilities of the algorithms CONLIN, MDQA, an GCM available in Boss Quattro to solve composite structure optimization. The algorithms are evaluated with respect to the optimization of sandwich panel parameters (ply thickness and orientation, and foam core thicknesss). [less ▲]

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See detailDamage modeling of laminated composites
Nguyen, Ba Nghiep; Fleury, Claude ULg

in Owen, D. R. J.; Onate, E. (Eds.) Computational plasticity: fundamentals and applications: proceedings of the fourth international conference held in Barcelona, Spain, 3rd-6th, April, 1995. Part I (1997)

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See detailTopology optimization involving discrete variables
Beckers, Maryse; Fleury, Claude ULg

in Gutkowski, Witold; Mróz, Zenon (Eds.) Proceedings of the second world congress of Structural and multidisciplinary optimization: May 26-30 1997, Zakopane, Poland (1997)

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See detailA modification of convex approximation methods for structural optimization
Zhang, Wei-Hong; Fleury, Claude ULg

in Computers & Structures (1997), 64(1-4), 89-95

The most popular convex approximation methods used today in structural optimization are discussed in this paper: the convex linearization method (CONLIN), the method of the moving asymptotes (MMA) and the ... [more ▼]

The most popular convex approximation methods used today in structural optimization are discussed in this paper: the convex linearization method (CONLIN), the method of the moving asymptotes (MMA) and the sequential quadratic programming method (SQP). Modifications are made to enhance the reliability of the CONLIN method. In addition, a generalized MMA (GMMA) is established. However, in view of practical difficulties of evaluating second-order derivatives, a fitting scheme is proposed in this work to adjust the convexity of the approximation based on the available function value at the preceding design iteration. Numerical results show that this simple scheme is efficient in our applications. [less ▲]

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See detailA primal-dual approach in truss topology optimization
Beekers, M.; Fleury, Claude ULg

in Computers & Structures (1997), 64(1-4), 77-88

The objective of truss topology optimization is to find, for a given weight, the stiffest truss, defined as a subset of an initially choosen set of bars called the ground structure. The restrictions are ... [more ▼]

The objective of truss topology optimization is to find, for a given weight, the stiffest truss, defined as a subset of an initially choosen set of bars called the ground structure. The restrictions are bounds on bar volumes and the satisfaction of equilibrium equations. For a single load case and without bounds on bar volumes, the problem can be written as a linear programming problem with nodal displacements as variables. The addition to the objective function of a quadratic term vanishing at the optimum allows us to use a dual solution scheme. A conjugate gradient method is well suited to maximize the dual function. Several ground structures are introduced. For large networks, those where each node is connected to those situated in a certain vicinity give a good compromise between generating a reasonable number of bars and obtaining a sufficient number of possible directions. Some examples taken from the literature are treated to illustrate the quality of the solution and the influence of initial topology. (C) 1997 Civil-Comp Ltd and Elsevier Science Ltd. [less ▲]

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See detailA Generalized Method of Moving Asymptotes (GMMA) Including Equality Constraints
Zhang, Weihong; Fleury, Claude ULg; Duysinx, Pierre ULg et al

in Structural Optimization (1996), 12(2/3), 143-146

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See detailA New Separable Approximation Scheme for Topological Problems and Optimization Problems Characterized by a Large Number of Design Variables
Duysinx, Pierre ULg; Zhang, Weihong; Fleury, Claude ULg et al

in Olhoff, Niels; Rozvany, Georges I.N. (Eds.) Proceedings of the First World Congress of Structural and Multidisciplinary Optimization (WCSMO1) (1995, May)

This paper is dedicated to a new convex separable approximation for solving optimization problems characterized by a very large number of design variables as in topology design. For such problems, the ... [more ▼]

This paper is dedicated to a new convex separable approximation for solving optimization problems characterized by a very large number of design variables as in topology design. For such problems, the convergence speed can be accelerated if one uses high quality approximation schemes for structural responses. To achieve this task, we propose, here, a new approximation procedure that belongs to the GMMA family. The originality of this new scheme is to rely on an automatic selection procedure of the asymptotes, using only first and zero order information accumulated during the previous iterations. This is possible owing to a diagonal Quasi-Newton update technique. Firstly, the new approximation procedure is validated on classical "benchmarks" of structural optimization. Then, it is compared to other schemes on a typical topology optimization problem. [less ▲]

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See detailStructural shape optimization and convex programming methods
Zhang, W. H.; Fleury, Claude ULg

Conference given outside the academic context (1995)

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See detailStructural Shape Optimization with Error Control
Duysinx, Pierre ULg; Zhang, Weihong; Zhong, H. G. et al

in Proceedings of 20th ASME Design Automation Conference (1994, September)

A robust and automatic shape optimization procedure is presented in this paper, which incorporates recent developments in the field of computer-aided design (CAD) of mechanical structures, such as ... [more ▼]

A robust and automatic shape optimization procedure is presented in this paper, which incorporates recent developments in the field of computer-aided design (CAD) of mechanical structures, such as geometric modelling, automatic selection of independent design variables, sensitivity analysis using reliable mesh perturbation schemes, error estimation and adaptive mesh refinement. A numerical example is given to show the efficiency of the procedure. [less ▲]

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See detailA primal-dual approach in truss topology optimization
Beckers, Maryse; Fleury, Claude ULg

in Topping, B. H. V.; Papadrakakis, Manolis (Eds.) Advances in Structural Optimization (1994)

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See detailRecent advances in convex approximation methods for structural optimization
Zhang, W. H.; Fleury, Claude ULg

in Topping, B. H. V.; Papadrakakis, Manolis (Eds.) Advances in Structural Optimization (1994)

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See detailSensitivity Analysis With Unstructured Free Mesh Generators in 2-D Shape Optimization
Duysinx, Pierre ULg; Zhang, Weihong; Fleury, Claude ULg

in Herskowitz, José (Ed.) Proceedings of Structural Optimization 93, The World Congress on Optimal Design of Structural Systems (1993, August)

Shape optimization has to consider new progress in mesh generators to take full benefits from the use of free unstructured meshes in realistic industrial optimization. The main difficulty relies in the ... [more ▼]

Shape optimization has to consider new progress in mesh generators to take full benefits from the use of free unstructured meshes in realistic industrial optimization. The main difficulty relies in the mesh flow determination during sensitivity analysis. The authors present their experience in applying smoothing techniques to transmit boundary perturbations to the inner mesh. It is explained how smoothing can be used to evaluate velocity fields in a simple and inexpensive way while guarantying reliability, efficiency and precision. A wide range of smoothing procedures are compared and confronted with other velocity field approaches to investigate their advantages and drawback. Finally, applications of smoothing procedures in the commercial optimization package OPTI-SAMCEF are described. [less ▲]

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See detailA Parametric Design Based Approach to Structural Shape Optimization
ZHANG, W. H.; Beckers, Pierre ULg; Duysinx, Pierre ULg et al

Conference given outside the academic context (1993)

Detailed reference viewed: 47 (2 ULg)