References of "Duysinx, Pierre"
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See detailModeling of Electro-mechanical coupling in MEMS
Rochus, Véronique ULg; Duysinx, Pierre ULg; Golinval, Jean-Claude ULg

Scientific conference (2002)

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See detailTopology optimization with self-weight loading: (un-expected) problems and solutions
Bruyneel, Michaël ULg; Duysinx, Pierre ULg

in Bendsoe, M. P.; Olhoff, Niels; Rassmussen, John (Eds.) Proceedings of the 2nd Max Planck Workshop on Engineering Design Optimization (2001, October)

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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 detailL’Optimisation Topologique en Mécanique
Duysinx, Pierre ULg

Article for general public (1999)

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See detailCompressor and Turbine Blade Design by Optimization
Léonard, Olivier ULg; Rothilde, André; Duysinx, Pierre ULg

in Bloebaum, C. (Ed.) Proceedings of the 3rd World Congress of Structural and Multidisciplinary Optimization WCSMO3 (1999, May)

Compressor and turbine blade design involves thermodynamical, aerodynamical and mechanical aspects, resulting in an important number of iterations. Inverse methods and optimization procedures help the ... [more ▼]

Compressor and turbine blade design involves thermodynamical, aerodynamical and mechanical aspects, resulting in an important number of iterations. Inverse methods and optimization procedures help the designer in this long and eventually frustrating process. In this paper an optimization procedure is presented which solves two types of two-dimensional or quasi-three-dimensional problems: the inverse problem, for which a target velocity distribution is imposed, and a more global problem, in which the aerodynamic load is maximized. [less ▲]

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See detailAlmost Isotropic Perimeters in Topology Optimization: Theoretical and Numerical Aspects
Petersson, Joakim; Beckers, Muriel; Duysinx, Pierre ULg

in Bloebaum, C. (Ed.) Proceedings of the 3rd World Congress of Structural and Multidisciplinary Optimization WCSMO3 (1999, May)

We consider topology optimization of elastic continuum structures including a bound on the perimeter of the structural domain. Such a bound is known to ensure existence of solutions and it stabilizes the ... [more ▼]

We consider topology optimization of elastic continuum structures including a bound on the perimeter of the structural domain. Such a bound is known to ensure existence of solutions and it stabilizes the behavior of numerical finite element (FE) solutions. However the straightforward way of calculating the perimeter is rotationally mesh-dependent. In this paper we present new perimeter formulae with weaker rotational dependence i.e. perimeters that are almost isotropic. An overview of some theoretical results as well as numerical tests are given. [less ▲]

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See detailTopology Optimization with Different Stress Limit in Tension and Compression
Duysinx, Pierre ULg

in Bloebaum, C. (Ed.) Proceedings of the 3rd World Congress of Structural and Multidisciplinary Optimization WCSMO3 (1999, May)

This report presents new progresses in topology optimization of continuum structures with stress constraints. One principal contribution consists in the consideration of equivalent stress criteria which ... [more ▼]

This report presents new progresses in topology optimization of continuum structures with stress constraints. One principal contribution consists in the consideration of equivalent stress criteria which can generalization of von Mises criterion and which are able to take into account non equal stress limits in tension and compression. A literature review led us to consider Raghava and Ishai criteria, which include a contribution of hydrostatic pressure. With the help of these criteria topology optimization can predict more realistic designs in which structural members are able to withstand better tension loads than compression loads, or vice-versa, as it is sometimes encountered in civil engineering or in composite material design. The implementation and sensitivity analysis aspects of Raghava and Ishai criteria in the Finite Element context are presented. We also present recent advanced developments to the solution of topology problems with stress constraints like the stress constraint relaxation technique and the numerical optimization procedure based on convex approximations and dual optimizers. Finally numerical applications will show the original character of the stress based topology designs ad versus compliance designs when there are unequal stress limits or when there are more than one load case. [less ▲]

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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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Peer Reviewed
See detailTopology Optimization of Continuum Structures with Local Stress Constraints
Duysinx, Pierre ULg; Bendsoe, Martin Philip

in International Journal for Numerical Methods in Engineering (1998), 43

We introduce an extension of current technologies for topology optimization of continuum structures which allows for treating local stress criteria. We rst consider relevant stress criteria for porous ... [more ▼]

We introduce an extension of current technologies for topology optimization of continuum structures which allows for treating local stress criteria. We rst consider relevant stress criteria for porous composite materials, initially by studying the stress states of the so-called rank 2 layered materials. Then, on the basis of the theoretical study of the rank 2 microstructures, we propose an empirical model which extends the power penalized sti ness model (also called SIMP for Solid Isotropic Microstructure with Penalization for intermediate densities). In a second part, solution aspects of topology problems are considered. To deal with the so-called 'singularity' phenomenon of stress constraints in topology design, an -constraint relaxation of the stress constraints is used. We describe the mathematical programming approach that is used to solve the numerical optimization problems, and show results for a number of example applications. [less ▲]

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See detailNew Developments in Handling Stress Constraints in Optimal Material Distributions
Duysinx, Pierre ULg; Sigmund, Ole

in Proceedings of 7th AIAA/USAF/NASA/ISSMO symposium on Multidisciplinary Design Optimization (1998)

There is a general interest to consider stress constraints in topology optimization of continuum structures. By their very nature stress constraints are local constraints which result in large scale ... [more ▼]

There is a general interest to consider stress constraints in topology optimization of continuum structures. By their very nature stress constraints are local constraints which result in large scale optimization problems that are often expensive to solve. Here in order to reduce the computing the effort we explore an alternative technique based on equivalent global (that is integrated) constraints. We define two global stress constraints based on the p-norm and p-mean of the epsilon-relaxed overall stress criteria in the finite elements. We present a new formulation of the epsilon-relaxation technique which is better suited to topology optimization of continuum structures and which makes the relaxation process automatic. The "p-mean" and "p-norm" functions bound by lower and upper value the maximum value of the epsilon-relaxed overall stress criterion. Based on numerical experiments this study compares the global and the local constraint formulations. Even if the use of integrated constraints leads a reduction of the computing time by one or two orders of magnitude, they definitely give a weaker control of local stress level. This sometimes can lead to solutions that are a bit different. [less ▲]

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See detailTopology Optimization of Continuum Structures with Stress Constraints
Duysinx, Pierre ULg; Bendsoe, Martin Philip

in Gutkowski, W.; Mroz, Z. (Eds.) Proceedings of the Second World Congress of Structural and Multidisciplinary Optimization (WCSMO2) (1997, May)

We introduce an extension of topology optimization of continuum structures to deal with local stress criteria. We first consider relevant stress criteria for porous composite materials, initially by ... [more ▼]

We introduce an extension of topology optimization of continuum structures to deal with local stress criteria. We first consider relevant stress criteria for porous composite materials, initially by studying the stress states of the so-called rank 2 layered materials. Then, an empirical model is proposed for the power law materials (also called SIMP materials). In a second part, solution aspects of topology problems are considered. To deal with the so-called 'singularity' phenomenon of stress constraints in topology design, an $\epsilon$ constraint relaxation of the stress constraints is used. We describe the mathematical programming approach that is used to solve the numerical optimization problems. The proposed strategy is applied to illustrative applications. [less ▲]

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See detailLayout Optimization : A Mathematical Programming Approach
Duysinx, Pierre ULg

Report (1997)

This paper presents applications of specially tailored methods of the mathematical programming approach for solving topology design problems formulated as an optimal material distribution, providing a way ... [more ▼]

This paper presents applications of specially tailored methods of the mathematical programming approach for solving topology design problems formulated as an optimal material distribution, providing a way to enlarge the scope of potential applications of topology optimization. The first feature of the methodology is to resort to dual maximization to solve optimization problems with a huge number of design variables, using the concept of Sequential Convex Programming (SCP). Here a central theme is the choice of convex approximations suited to the problems. First order approximations are firstly considered and compared. However, to increase the performances of the procedures (for example, to reduce the number of steps to arrive to a stationary design), a new approach to build un-expensive second approximation schemes, especially relevant for large scale problems, have been developed and validated. To illustrate the efficiency of the mathematical programming approach, the final part of the paper deals with an efficient treatment of perimeter constraints. Such constraints are essential to regularize material distribution with non optimal microstructures, but perimeter constraints are very difficult to handle in a numerical procedure for practical designs. The paper presents a solution to this problem that has been implemented and validated on a wide range of applications. [less ▲]

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See detailConvex Approximation Methods for Large Scale Structural Problems
Duysinx, Pierre ULg

in Proceedings of the 9th Nordic Seminar on Computational Mechanics (NSCM IX) (1996, October)

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See detailLayout Optimization : A Mathematical Programming Approach
Duysinx, Pierre ULg

Conference (1996, August)

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See detailIntroduction à l'optimisation topologique
Duysinx, Pierre ULg

Report (1996)

Detailed reference viewed: 44 (5 ULg)
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See detailOPTIMISATION TOPOLOGIQUE : DU MILIEU CONTINU A LA STRUCTURE ELASTIQUE
Duysinx, Pierre ULg

Doctoral thesis (1996)

Detailed reference viewed: 216 (23 ULg)
Peer Reviewed
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 ▲]

Detailed reference viewed: 96 (2 ULg)