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 References of "Duysinx, Pierre"      in Complete repository Arts & humanities   Archaeology   Art & art history   Classical & oriental studies   History   Languages & linguistics   Literature   Performing arts   Philosophy & ethics   Religion & theology   Multidisciplinary, general & others Business & economic sciences   Accounting & auditing   Production, distribution & supply chain management   Finance   General management & organizational theory   Human resources management   Management information systems   Marketing   Strategy & innovation   Quantitative methods in economics & management   General economics & history of economic thought   International economics   Macroeconomics & monetary economics   Microeconomics   Economic systems & public economics   Social economics   Special economic topics (health, labor, transportation…)   Multidisciplinary, general & others Engineering, computing & technology   Aerospace & aeronautics engineering   Architecture   Chemical engineering   Civil engineering   Computer science   Electrical & electronics engineering   Energy   Geological, petroleum & mining engineering   Materials science & engineering   Mechanical engineering   Multidisciplinary, general & others Human health sciences   Alternative medicine   Anesthesia & intensive care   Cardiovascular & respiratory systems   Dentistry & oral medicine   Dermatology   Endocrinology, metabolism & nutrition   Forensic medicine   Gastroenterology & hepatology   General & internal medicine   Geriatrics   Hematology   Immunology & infectious disease   Laboratory medicine & medical technology   Neurology   Oncology   Ophthalmology   Orthopedics, rehabilitation & sports medicine   Otolaryngology   Pediatrics   Pharmacy, pharmacology & toxicology   Psychiatry   Public health, health care sciences & services   Radiology, nuclear medicine & imaging   Reproductive medicine (gynecology, andrology, obstetrics)   Rheumatology   Surgery   Urology & nephrology   Multidisciplinary, general & others Law, criminology & political science   Civil law   Criminal law & procedure   Criminology   Economic & commercial law   European & international law   Judicial law   Metalaw, Roman law, history of law & comparative law   Political science, public administration & international relations   Public law   Social law   Tax law   Multidisciplinary, general & others Life sciences   Agriculture & agronomy   Anatomy (cytology, histology, embryology...) & physiology   Animal production & animal husbandry   Aquatic sciences & oceanology   Biochemistry, biophysics & molecular biology   Biotechnology   Entomology & pest control   Environmental sciences & ecology   Food science   Genetics & genetic processes   Microbiology   Phytobiology (plant sciences, forestry, mycology...)   Veterinary medicine & animal health   Zoology   Multidisciplinary, general & others Physical, chemical, mathematical & earth Sciences   Chemistry   Earth sciences & physical geography   Mathematics   Physics   Space science, astronomy & astrophysics   Multidisciplinary, general & others Social & behavioral sciences, psychology   Animal psychology, ethology & psychobiology   Anthropology   Communication & mass media   Education & instruction   Human geography & demography   Library & information sciences   Neurosciences & behavior   Regional & inter-regional studies   Social work & social policy   Sociology & social sciences   Social, industrial & organizational psychology   Theoretical & cognitive psychology   Treatment & clinical psychology   Multidisciplinary, general & others     Showing results 101 to 120 of 127     1 2 3 4 5 6 7     Recent Progress In Preliminary Design Of Mechanical Components With Topology OptimizationDuysinx, Pierre ; Bruyneel, Michaël in Chedmail, Patrick; Cognet, Gérard; Fortin, Clément (Eds.) et al Integrated Design and Manufacturing in Mechanical Engineering (2002)Since 10 years topology optimisation has been trying to bring an efficient answer to the problem of automatic choice of morphology of mechanical components. This choice is one of the main questions to be ... [more ▼]Since 10 years topology optimisation has been trying to bring an efficient answer to the problem of automatic choice of morphology of mechanical components. This choice is one of the main questions to be addressed during the preliminary design phase of mechanical and structural components. By topology or morphology of a mechanical or structural component one means here all the basic data that touch the layout. So topology covers for example the number and the relative positions of the wholes in the structural domains, the number and the nature of the structural members, their connectivity and the character of the connecting joints. Before having topology optimisation tool, the selection of the mechanical morphology had been let to engineers’ experience or (even worse sometimes) to their intuition. For example it was a common use in industry to take the topology of an existing product and to use it as it is for the new design. With topology optimisation the choice of morphology can now rely on rational arguments and can be made in order to fit to the product characteristics. Furthermore mathematical tools, because of the optimisation formulation of the design problem, drive the determination of the structural layout. This has two advantages. At first topology optimisation can facilitate the automation of preliminary design steps. Then it can improve substantially the performance of new mechanical products. This means that topology optimisation can propose original and innovative solutions to engineering problems. Some authors suggested that in some problems topology could lead to a gain of performance that could grow up to 50 percents. This paper reports some novel contributions to topology optimisation techniques. Two areas will be addressed. The first one is concerned with recent progress related to the perimeter method of topology optimisation. The perimeter method, which was originally introduced by Haber et al (1996) in topology optimisation, consists in bounding the perimeter of the material distribution in addition to its area. At first recent research focussed on extending the method to 3-D structures. Then other work was made to new quasi-isotropic measures of the perimeter that are nearly insensitive to the mesh. The second axis of our work has been devoted to the treatment of stress constraints. We have continued along the initial work of Duysinx and Bendsøe (1998). The new developments were made to consider stress constraints in practical (industrial) design problems. Firstly we investigated the formulation of the problem in terms of global (i.e. integrated) stress constraints instead of the local stress constraints which can be very cumbersome for practical applications. A second research was devoted to extend the classic von Mises equivalent stress criterion to other kinds of criteria. Indeed in many cases such as in structures made of a material with unequal stress limits, the von Mises criterion is unable to predict a correct topology design. In order to include the effect of different behaviours in tension and compression, we are going to show that Raghava and Ishai quadratic criteria can be used. Finally in the final stage of the paper we will discuss the position of topology optimisation in the design chain. Usual answers in accordance with the current state of the art consider this topology tool as a preliminary design tool. However our experience lead us to a more complicated answer. In a similar way to stress constraints, the ‘optimal’ topology can be dependent on all the design constraints and not only stiffness performance. These constraints can come from the structural (or functional) behaviour, but they can also be related to the manufacturing aspects. Our experience showed that perimeter constraint is quite efficient to limit the design complexity in same cases, especially for planar structures. However this perimeter constraint can lead designs that are totally impossible to manufacture especially in 3-D. For example, perimeter constraint never prevents included wholes that would be impossible to carve out with some fabrication techniques. Thus we come to the conclusion that new progress in topology optimisation should be oriented towards a simultaneous approach of the design problem including most of the functional requirements as well as of the manufacturing restrictions. [less ▲]Detailed reference viewed: 44 (3 ULg) Modeling of Electro-mechanical coupling in MEMSRochus, Véronique ; Duysinx, Pierre ; Golinval, Jean-Claude Scientific conference (2002)Detailed reference viewed: 23 (4 ULg) Topology optimization with self-weight loading: (un-expected) problems and solutionsBruyneel, Michaël ; Duysinx, Pierre in Bendsoe, M. P.; Olhoff, Niels; Rassmussen, John (Eds.) Proceedings of the 2nd Max Planck Workshop on Engineering Design Optimization (2001, October)Detailed reference viewed: 36 (0 ULg) A family of MMA approximations for structural optimizationBruyneel, Michaël ; Duysinx, Pierre ; Fleury, Claude 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 ▲]Detailed reference viewed: 90 (3 ULg) Estimating diagonal second order terms in structural approximations with quasi-Cauchy techniquesDuysinx, Pierre ; Nguyen, Van Hien; Bruyneel, Michaël et alin 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 ▲]Detailed reference viewed: 20 (0 ULg) Composite structures design for strength and stiffness with respect to ply thickness and/or fibers orientationBruyneel, Michaël ; Duysinx, Pierre ; Fleury, Claude 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 ▲]Detailed reference viewed: 41 (3 ULg) L’Optimisation Topologique en MécaniqueDuysinx, Pierre Article for general public (1999)Detailed reference viewed: 24 (3 ULg) Compressor and Turbine Blade Design by OptimizationLéonard, Olivier ; Rothilde, André; Duysinx, Pierre 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 ▲]Detailed reference viewed: 70 (2 ULg) Almost Isotropic Perimeters in Topology Optimization: Theoretical and Numerical AspectsPetersson, Joakim; Beckers, Muriel; Duysinx, Pierre 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 ▲]Detailed reference viewed: 37 (2 ULg) Topology Optimization with Different Stress Limit in Tension and CompressionDuysinx, Pierre 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 ▲]Detailed reference viewed: 146 (2 ULg) Enhanced Approximation Schemes for Classical Optimization AlgorithmBruyneel, Michaël ; Vermaut, O.; Duysinx, Pierre et alReport (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 ▲]Detailed reference viewed: 18 (0 ULg) Topology Optimization of Continuum Structures with Local Stress ConstraintsDuysinx, Pierre ; Bendsoe, Martin Philipin International Journal for Numerical Methods in Engineering (1998), 43We 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 ▲]Detailed reference viewed: 63 (3 ULg) New Developments in Handling Stress Constraints in Optimal Material DistributionsDuysinx, Pierre ; Sigmund, Olein 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 ▲]Detailed reference viewed: 255 (1 ULg) Topology Optimization of Continuum Structures with Stress ConstraintsDuysinx, Pierre ; Bendsoe, Martin Philipin 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 ▲]Detailed reference viewed: 46 (1 ULg) Layout Optimization : A Mathematical Programming ApproachDuysinx, Pierre 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 ▲]Detailed reference viewed: 77 (0 ULg) Convex Approximation Methods for Large Scale Structural ProblemsDuysinx, Pierre in Proceedings of the 9th Nordic Seminar on Computational Mechanics (NSCM IX) (1996, October)Detailed reference viewed: 24 (0 ULg) Layout Optimization : A Mathematical Programming ApproachDuysinx, Pierre Conference (1996, August)Detailed reference viewed: 6 (1 ULg) Introduction à l'optimisation topologiqueDuysinx, Pierre Report (1996)Detailed reference viewed: 28 (3 ULg) OPTIMISATION TOPOLOGIQUE : DU MILIEU CONTINU A LA STRUCTURE ELASTIQUEDuysinx, Pierre Doctoral thesis (1996)Detailed reference viewed: 86 (11 ULg) A Generalized Method of Moving Asymptotes (GMMA) Including Equality ConstraintsZhang, Weihong; Fleury, Claude ; Duysinx, Pierre et alin Structural Optimization (1996), 12(2/3), 143-146Detailed reference viewed: 65 (3 ULg)