References of "Bruyneel, Michaël"
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See detailDiscussion on the optimization problem formulation of flexible components in multibody systems
Tromme, Emmanuel ULg; Bruls, Olivier ULg; Emonds-Alt, Jonathan et al

in Structural and Multidisciplinary Optimization (2013), 48(6), 1189-1206

This paper is dedicated to the structural optimization of flexible components in mechanical systems modeled as multibody systems. While most of the structural optimization developments have been conducted ... [more ▼]

This paper is dedicated to the structural optimization of flexible components in mechanical systems modeled as multibody systems. While most of the structural optimization developments have been conducted under (quasi-)static loadings or vibration design criteria, the proposed approach aims at considering as precisely as possible the effects of dynamic loading under service conditions. Solving this problem is quite challenging and naive implementations may lead to inaccurate and unstable results. To elaborate a robust and reliable approach, the optimization problem formulation is investigated because it turns out that it is a critical point. Different optimization algorithms are also tested. To explain the efficiency of the various solution approaches, the complex nature of the design space is analyzed. Numerical applications considering the optimization of a two-arm robot subject to a trajectory tracking constraint and the optimization of a slider-crank mechanism with a cyclic dynamic loading are presented to illustrate the different concepts. [less ▲]

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See detailComparison of parameterization schemes for solving the discrete material optimization problem of composite structures
Duysinx, Pierre ULg; Guillermo Alonso, Maria ULg; Gao, Tong et al

Conference (2013, September)

In the context of weight reduction challenges in aerospace, automotive, and energy engineering problems, composite materials are gaining a revived interested. Because of the problem complexity and the ... [more ▼]

In the context of weight reduction challenges in aerospace, automotive, and energy engineering problems, composite materials are gaining a revived interested. Because of the problem complexity and the large number of design variables, their design of composite structures is greatly facilitated by using optimization techniques. While several formulations have been proposed for composite structure design, Stegmann and Lund [1] have showed that composite optimization can take advantage of the topology optimization approach. The fundamental idea of the Discrete Material Optimization (DMO) approach is 1/ to formulate the composite optimization problem as an optimal material selection problem in which the different laminates and ply orientations are considered as different materials and 2/ to solve the optimization problem using continuous existence variables. To transform the discrete problem into a continuous one, one introduces a suitable parametrization identifying each material by a unique set of design variables while the material properties are expressed as a weighted sum of all candidate materials. Using DMO approach, one can solve within a common approach, different design problems such as laminate distribution problem, stacking sequence optimization... The inherent difficulties of the discrete material selection using topology optimization are 1/ to find efficiency interpolation and penalization schemes of the material properties and 2/ to be able to tailor an efficient solution algorithm to handle very large scale optimization problems. Besides the reference DMO scheme by Lund and his co-authors, other interpolation schemes have been proposed: In this paper, work we are considering and comparing DMO with two other schemes namely the Shape Function with Penalization Parameterization (SFP) by Bruyneel [2] and it recent extension, the Bi-value Coding Parametrization (BCP) by Gao et al. [3]. In particular, the work considers the different schemes in the perspective of solving large-scale industrial applications. The work considers several aspects of the different schemes: • Nature of the different interpolation schemes, • Penalization strategies (power law (SIMP), RAMP, Tsai-Halpin or polynomial), • Number of design variables, the size and complexity of the optimization problem, • Sensitivity to local optima, to the initial design variable, and the development of continuous penalization techniques, • Ability to be extended to various formulations from compliance problems to local restrictions and buckling. As a major drawback, DMO, SFP and BCP approaches increase dramatically the number of design variables. Because of the computational burden to solve the optimization problems, in most of DMO implementations, the considered structural responses are generally limited to compliance-like objective functions. In order to extend the DMO formulation, the work investigates the selection of the most appropriate and efficient optimization algorithms to handle the problems. Different schemes of the sequential convex programming are compared. At first the classic schemes MMA and CONLIN are tested. Then more advanced schemes of the MMA family (Bruyneel et al. [4]) are experimented. The work and the comparisons are carried out on several numerical applications related to the selection of optimal local fibre orientations (with up to 36 candidate material orientations) in membrane and shell aerospace or automotive structures. The various numerical test problems include academic examples and benchmarks inspired by industrial applications. [less ▲]

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See detailComparison of parameterization schemes for solving the discrete material optimization problem of composite structures
Duysinx, Pierre ULg; Guillermo Alonso, Maria ULg; Tong, Gao et al

in Halftka, Raphael; KIM, Nam Ho (Eds.) Proceeding of the 10th World Congress on Structural And Multidisciplinary Optimization (2013, May 19)

Optimal design of composite structures can be formulated as an optimal selection of material in a list of different laminates. Based on the seminal work by Stegmann and Lund, the optimal problem can be ... [more ▼]

Optimal design of composite structures can be formulated as an optimal selection of material in a list of different laminates. Based on the seminal work by Stegmann and Lund, the optimal problem can be stated as a topology optimization problem with multiple materials. The research work carries out a large investigation of different interpolation and penalization schemes for the optimal material selection problem. Besides the classical Design Material Optimization (DMO) scheme and the recent Shape Function with Penalization (SFP) scheme by Bruyneel, the research introduces a generalization of the SFP approach using a bi-value coding parameterization (BCP) by Gao, Zhang and Duysinx. The paper provides a comparison of the different parameterization approaches. It also proposes alternative penalization schemes and it investigates the effect of the power penalization. Finally, we discuss the solution aspects in the perspective of solving large-scale industrial applications. The conclusions are illustrated by a numerical application for the compliance maximization of an in-plane composite ply. [less ▲]

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See detailExtensions of the Shape Functions with Penalization Parameterization for Composite-Ply Optimization
Bruyneel, Michaël ULg; Duysinx, Pierre ULg; Fleury, Claude ULg et al

in AIAA Journal (2011), 49(10), 2325-2329

The SFP method proposed is an alternative to the discrete material optimization (DMO) approach developed. Both approaches are an extension of the multiphase topology optimization. Here, SFP is used to ... [more ▼]

The SFP method proposed is an alternative to the discrete material optimization (DMO) approach developed. Both approaches are an extension of the multiphase topology optimization. Here, SFP is used to select composite plies in a set of candidate orientations, in a formulation including ontinuous design variables. [less ▲]

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See detailNew developments for an efficient solution of the discrete material topology optimization of composite structures
Duysinx, Pierre ULg; Gao, Tong; Zhang, Weihong et al

in Faester, S.; Juul Jensen, D.; Ralph, B. (Eds.) et al Composite materials for structural performance: towards the higher limits (2011, September 05)

Optimal design of composite structures can be formulated as an optimal selection of material in a list of different laminates. Based on the seminal work by Stegmann and Lund (2005), the optimal problem ... [more ▼]

Optimal design of composite structures can be formulated as an optimal selection of material in a list of different laminates. Based on the seminal work by Stegmann and Lund (2005), the optimal problem can be stated as a topology optimization problem with multiple materials. The research work carries out a large investigation of different interpolation and penalization schemes for the optimal material selection problem. Besides the classical Design Material Optimization (DMO) scheme and the recent Shape Function with Penalization (SFP) scheme by Bruyneel (2011), the research introduces a generalization of the SFP approach using a bi-value coding parameterization (BCP) (Gao, Zhang, and Duysinx, 2011) The paper provides a comparison of the different parameterization approaches. It also proposes alternative penalization schemes and it investigates the effect of the power penalization. Finally, we discuss the solution aspects in the perspective of solving large-scale industrial applications. The conclusions are illustrated by a numerical application for the compliance maximization of an in-plane composite ply. [less ▲]

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See detailInterface element for delamination simulation. A good usage for accuracy and performances.
Delsemme, Jean-Pierre; Bruyneel, Michaël ULg; Jetteur, Philippe et al

Conference (2011, June 29)

This paper deals with the use of interface element for the simulation of crack propagation. The questions: "how to choose mesh size, material properties and model parameters in order to get a correct ... [more ▼]

This paper deals with the use of interface element for the simulation of crack propagation. The questions: "how to choose mesh size, material properties and model parameters in order to get a correct result in a reasonable time" will be discussed. An industrial test case with skin-stringer separation will also be presented. [less ▲]

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See detailAdvances in optimization of flexible components in mutlibody systems: Application to robot-arms design
Duysinx, Pierre ULg; Emonts-Alt, Jonhatan; Virlez, Geoffrey ULg et al

in Proceedings of the 5th Asian Conference on Multibody Dynamics (2010, August)

The paper considers the optimization of the flexible components of mechanical systems modeled as multibody systems. This approach aims at considering as precisely as possible the dynamic loading of the ... [more ▼]

The paper considers the optimization of the flexible components of mechanical systems modeled as multibody systems. This approach aims at considering as precisely as possible the dynamic loading of the structural components under service conditions in their mechanical systems. While most of the structural optimization developments have been conducted under static or quasi static conditions, the approach is clearly a challenge. Naïve applications of this approach generally lead to fragile and unstable results. To elaborate a robust and reliable approach, we investigate and compare several formulations of the optimization problem. Different optimization algorithms are also tested. To explain the efficiency of the various solution approaches, the complex nature of the design space is investigated. The developments are illustrated using the test-case of the structural design of the links of a two-arm robot subject to a trajectory tracking constraint. [less ▲]

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See detailTopology and generalized shape optimisation: why stress constraints are so important?
Duysinx, Pierre ULg; Van Miegroet, Laurent ULg; Lemaire, Etienne ULg et al

in International Journal of Simulation & Multidisciplinary Design Optimization (2008), 2(4), 253-258

The paper continues along the work initiated by the authors in taking into account stress constraints in topology optimization of continuum structures. Revisiting some of their last developments in this ... [more ▼]

The paper continues along the work initiated by the authors in taking into account stress constraints in topology optimization of continuum structures. Revisiting some of their last developments in this field, the authors point out the importance of considering stress constraints as soon as the preliminary design phase, that is, to include stress constraints in the topology optimization problem in order to get the most appropriate structural lay-out. Numerical applications that can be solved using these new developments make possible to exhibit interesting results related to the specific nature of strength based structural lay out for maximum strength compared to maximum stiffness. This particular character of stress design is clearly demonstrated in two kinds of situations: once several load cases are considered and when unequal stress limits in tension and compression are involved. [less ▲]

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See detailStress constrained topology and shape optimization : Specific character and large scale optimization algorithms
Duysinx, Pierre ULg; Fleury, Claude; Van Miegroet, Laurent ULg et al

in Proceedings of the 8th World Congress on Computational Mechanics (WCCM) (2008)

Detailed reference viewed: 12 (2 ULg)
See detailCOMBOX: A Distributed Computing Process for Pre-Sizing of Composite Aircraft Box Structures
Krog, L.; Bruyneel, Michaël ULg; Remouchamps, Alain et al

Conference given outside the academic context (2007)

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See detailAn augmented Lagrangian optimization method for inflatable structures analysis problems
Bruyneel, Michaël ULg; Jetteur, Pierre ULg; Granville, D. et al

in Structural and Multidisciplinary Optimization (2006), 32(5), 383-395

This paper describes the development of an augmented Lagrangian optimization method for the numerical simulation of the inflation process in the design of inflatable space structures. Although the Newton ... [more ▼]

This paper describes the development of an augmented Lagrangian optimization method for the numerical simulation of the inflation process in the design of inflatable space structures. Although the Newton-Raphson scheme was proven to be efficient for solving many nonlinear problems, it can lead to lack of convergence when it is applied to the simulation of the inflation process. As a result, it is recommended to use an optimization algorithm to find the minimum energy configuration that satisfies the equilibrium equations characterizing the final shape of the inflated structure subject to an internal pressure. On top of that, given that some degrees of freedom may be linked, the optimum may be constrained, and specific optimization methods for constrained problems must be considered. The paper presents the formulation and the augmented Lagrangian method (ALM) developed in SAMCEF Mecano for inflatable structures analysis problems. The related quasi-unconstrained optimization problem is solved with a nonlinear conjugate gradient method. The Wolfe conditions are used in conjunction with a cubic interpolation for the line search. Equality constraints are considered and can be easily treated by the ALM formulation. Numerical applications present simulations of unconstrained and constrained inflation processes (i.e., where the motion of some nodes is ruled by a rigid body element restriction and/or problems including contact conditions). [less ▲]

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See detailSolution of topology optimization problems with sequential convex programming
Duysinx, Pierre ULg; Bruyneel, Michaël ULg; Fleury, Claude ULg

Speech (2003)

Introduction to efficient solution algorithms to large scale topology optimization problems.

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

in Structural and Multidisciplinary Optimization (2002), 24(4), 263-276

This paper proposes a new first-order approximation scheme used for solving structural optimization problems. It is based on approximations of the MMA family (MMA and GCMMA), but it utilizes the gradients ... [more ▼]

This paper proposes a new first-order approximation scheme used for solving structural optimization problems. It is based on approximations of the MMA family (MMA and GCMMA), but it utilizes the gradients and/or the function values at two successive design points to improve the quality of the approximation. In addition, this scheme can consider simultaneously monotonous and nonmonotonous structural behaviour. According to the characteristics of the treated problem, one of the approximations or a mix of them is automatically selected. Based on this approach, the accuracy of the approximated subproblems is improved and the solution process can be sped up. Numerical results compare the effectiveness of the method with previously derived approximations of the MMA family for shape optimization of trusses and for composite design problems. The benefit of using mixed approximations is also discussed. [less ▲]

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See detailSelection of approximation schemes in topology optimization
Bruyneel, Michaël ULg; Duysinx, Pierre ULg

in Hogge, Michel (Ed.) Proceedinsg of the ACOMEN 2002, 2nd International Conference on Advanced Computational Methods in Engineering (2002, May)

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See detailComposite structures optimization using sequential convex programming
Bruyneel, Michaël ULg; Fleury, Claude ULg

in Advances in Engineering Software (2002), 33(7-10), 697-711

The design of composite structures is considered here. The approximation concepts approach is used to solve the optimization problem. The convex approximations of the MMA family are briefly described ... [more ▼]

The design of composite structures is considered here. The approximation concepts approach is used to solve the optimization problem. The convex approximations of the MMA family are briefly described. Several modifications of these approximations are presented. They are now based on gradient information at two successive iterations, avoiding the use of the expensive second-order derivatives. A two-point fitting scheme is also described, where the function value at the preceding design point is used to improve the approximation. Numerical examples compare these new purely non-monotonous schemes to the existing ones for the selection of optimal fibers orientations in laminates. It is shown how these two-point based approximations are well adapted to the problem and can improve the optimization task, leading to reasonable computational efforts. A procedure is also derived for considering simultaneously monotonous and non-monotonous structural behaviors. The resulting generalized approximation scheme is well suited for the optimization of composite structures when both plies thickness and fibers orientations are considered as design variables. It is concluded that the newly developed approximation schemes of the MMA family are reliable for composite structures optimization. All the studied approximations are convex and separable: the optimization problem can then be solved using a dual approach. (C) 2002 Civil-Comp Ltd and Elsevier Science Ltd. All rights reserved. [less ▲]

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See detailRecent Progress In Preliminary Design Of Mechanical Components With Topology Optimization
Duysinx, Pierre ULg; Bruyneel, Michaël ULg

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 ▲]

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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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