References of "Tromme, Emmanuel"
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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 detailContact model between superelements in dynamic multibody systems
Virlez, Geoffrey ULg; Bruls, Olivier ULg; Sonneville, Valentin ULg et al

in Proceedings of ASME2013 International Design Engineering Technical Conference & Computers and Information in Engineering Conference IDETC/CIE 2013 (2013, August)

In this paper, a new contact formulation defined between flexible bodies modeled as superelements is investigated. Unlike rigid contact models, this approach enables to study the deformation and vibration ... [more ▼]

In this paper, a new contact formulation defined between flexible bodies modeled as superelements is investigated. Unlike rigid contact models, this approach enables to study the deformation and vibration phenomena induced by hard contacts. Compared with full-scale finite element models of flexible bodies, the proposed method is computationally more efficient, especially in case of a large number of bodies and contact conditions. The compliance of each body is described using a reduced-order elastic model which is defined in a corotational frame that follows the gross motion of the body. The basis used to reduce the initial finite element model relies on the Craig-Bampton method which uses both static boundary modes and internal vibration modes. The formulation of the contact condition couples all degrees of freedom of the reduced model in a nonlinear way. The relevance of the approach is demonstrated by simulation results first on a simple example, and then on a gear pair model. [less ▲]

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See detailStructural optimization of flexible components under dynamic loading within a multibody system approach: a comparative evaluation of optimization methods based on a 2-dof robot application.
Tromme, Emmanuel ULg; Bruls, Olivier ULg; Virlez, Geoffrey ULg et al

in Proceedings of the 10th World Congress on Structural and Multidisciplinary Optimization: Orlanda (USA), 19-24 mai 2013 (2013, May)

This paper is dedicated to a comparative evaluation between two methods of optimization to realize the structural optimization of flexible components in mechanical systems modeled as multibody systems. A ... [more ▼]

This paper is dedicated to a comparative evaluation between two methods of optimization to realize the structural optimization of flexible components in mechanical systems modeled as multibody systems. A nonlinear finite element method based formalism is considered for the dynamic simulation of the flexible multibody system. The first method is the Equivalent Static Load method which enables to transform a dynamic response optimization problem into a set of static response optimization problems. The second method treats directly the dynamic optimization problem in an integrated manner where the optimization process is carried out directly based on the time response coming from the multibody system approach. However, the first method proposed by Kang, Park and Arora was developed under the assumption that the multibody system is described using a floating frame of reference. Therefore, in order to carry on the comparison using a unique multibody system approach, a method is first proposed to derive the equivalent static loads when using a nonlinear finite element method based formalism. The comparative evaluation is then carried out on the simple academic example of the mass minimization of a two-arm robot subject to tracking deviation constraints. Conclusions are finally drawn for future work and stringent comparison. [less ▲]

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See detailModeling of joints with clearance and friction in multibody dynamic simulation of automotive differentials
Virlez, Geoffrey ULg; Bruls, Olivier ULg; Tromme, Emmanuel ULg et al

in Theoretical and Applied Mechanics Letters (2013), 3(1), 013003

Defects in kinematic joints can sometimes highly influence the simulation response of the whole multibody system within which these joints are included. For instance, the clearance, the friction, the ... [more ▼]

Defects in kinematic joints can sometimes highly influence the simulation response of the whole multibody system within which these joints are included. For instance, the clearance, the friction, the lubrication and the flexibility affect the transient behaviour, reduce the component life and produce noise and vibration for classical joints such as prismatics, cylindrics or universal joints. In this work, a new 3D cylindrical joint model which accounts for the clearance, the misalignment and the friction is presented. This formulation has been used to represent the link between the planet gears and the planet carrier in an automotive differential model. [less ▲]

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See detailEigenproblem formulation for electromechanical microsystem pull-in voltage optimization
Lemaire, Etienne ULg; Van Miegroet, Laurent ULg; Tromme, Emmanuel ULg et al

Conference (2013)

Electrostatic actuators are often used in MEMS since they are relatively easy to manufacture and provide a short response time. Previous studies have already considered topology optimization of such micro ... [more ▼]

Electrostatic actuators are often used in MEMS since they are relatively easy to manufacture and provide a short response time. Previous studies have already considered topology optimization of such micro-actuators like the work by Raulli and Maute [1] and by Yoon and Sigmund [2]. Raulli considers maximization of the actuator output displacement for given electric potential input locations. The paper by Yoon et al. goes further by replacing the staggered modeling used by Raulli by a monolithic approach where both physical fields (electric and mechanical) are solved at once. However, electrostatic micro-actuators possess a limit input voltage called the pull-in voltage, beyond which they become unstable. If a voltage greater than the pull-in voltage is applied to the device, elastic forces of the suspension system are not able to balance electrostatic forces and electrodes stick together. In some cases, the pull-in effect can damage the device. Previous researches by the authors [3] have considered the possibility to control pull-in voltage using topology optimization. In this first approach, pull-in voltage itself was included in the optimization problem and treated as objective function. Nevertheless, in some applications, the developed pull-in voltage optimization procedure suffers from design oscillations that prevent from reaching solution. As illustrated in this paper, the issue is similar to the mode switching problem that arises in eigenvalue optimization problems. The classical solution to this issue consists in including several eigenvalues in a ‘max-min’ formulation. However as the classical pull-in voltage optimization problem is not formulated as an eigenproblem, direct application is not possible. Indeed, pull-in being a nonlinear instability phenomenon, strictly speaking, it is only possible to compute one instability mode and upcoming instability modes cannot be captured. Therefore, this paper is dedicated to the development of a linear eigenproblem approximation for the nonlinear stability problem after the work on nonlinear buckling by Lindgaard and Lund [4]. The proposed stability eigenproblem leads to an alternative optimization procedure aiming at maximizing pull-in voltage. The first eigenmode corresponds to the actual pull-in mode while higher order modes allow estimating upcoming instability modes. Using a multiobjective formulation to maximize the smallest eigenvalue of the stability problem, it is possible to circumvent oscillation issues met with pull-in voltage optimization. Moreover, numerical results show that even if the eigenproblem formulation is an approximation of the actual pull-in voltage optimization problem, eigenproblem formulation leads to significant improvement of pull-in voltage. References [1] M. Raulli and K. Maute, Topology optimization of electrostatically actuated Microsystems, Struct. & Mult. Opt., 30(5):342-359, November 2005. [2] G.H. Yoon and O. Sigmund, A monolithic approach for topology optimization of electrostatically actuated devices, Comput. Methods Appl. Mech. Engrg., 194:4062-4075, 2008. [3] E. Lemaire, V. Rochus, J.-C. Golinval, and P. Duysinx, Microbeam pull-in voltage topology optimization including material deposition constraint, Comput. Methods Appl. Mech. Engrg., 194:4040-4050, 2008. [4] E. Lindgaard and E. Lund, Nonlinear bucking optimization of composite structures, Comput. Methods Appl. Mech. Engrg., 199:37-40, 2010. [less ▲]

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See detailModelling of contact between stiff bodies in automotive transmission systems
Virlez, Geoffrey ULg; Bruls, Olivier ULg; Poulet, Nicolas et al

in Fisette, Paul; Samin, Jean-Claude (Eds.) Multibody Dynamics: Computational Methods and Applications (2013)

Many transmission components contain moving parts, which can come into in contact. For example, the TORSEN differentials aremainly composed of gear pairs and thrust washers. The friction involved by ... [more ▼]

Many transmission components contain moving parts, which can come into in contact. For example, the TORSEN differentials aremainly composed of gear pairs and thrust washers. The friction involved by contacts between these two parts is essential in the working principle of such differentials. In this chapter, two different contact models are presented and exploited for the modelling of differentials. The former uses an augmented Lagrangian technique or a penalty method and is defined between two flexible bodies or between a rigid body and a flexible structure. The second contact formulation is a continuous impact modelling based on a restitution coefficient. [less ▲]

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See detailModelling of joints with clearance and friction in multibody dynamic simulation of automotive differentials
Virlez, Geoffrey ULg; Bruls, Olivier ULg; Tromme, Emmanuel ULg et al

in Proceedings of the 6th Asian Conference on Multibody Dynamics (2012, August 27)

Defects in kinematic joints can sometimes highly influence the simulation response of the whole multibody system within which these joints are included. For instance, the clearance, the friction, the ... [more ▼]

Defects in kinematic joints can sometimes highly influence the simulation response of the whole multibody system within which these joints are included. For instance, the clearance, the friction, the lubrication and the flexibility affect the transient behaviour, reduce the component life and produce noise and vibration for classical joints such as prismatic, cylindric or universal joint. In this work, a new 3D cylindrical joint model which accounts for the clearance, the misalignment and the friction is presented. This formulation has been used to represent the link between the planet gears and the planet carrier in an automotive differential model. [less ▲]

Detailed reference viewed: 28 (12 ULg)
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See detailInvestigations on a Level Set based approach for the optimization of flexible components in multibody systems with a fixed mesh grid
Tromme, Emmanuel ULg; Bruls, Olivier ULg; Van Miegroet, Laurent ULg et al

in Proceedings of The 6th Asian Conference on Multibody Dynamics: Shanghai (China), 26-30 aout 2012 (2012, August)

This paper considers the optimization of flexible components in mechanical systems thanks to a "fully integrated" optimization method which includes a flexible multibody system simulation based on ... [more ▼]

This paper considers the optimization of flexible components in mechanical systems thanks to a "fully integrated" optimization method which includes a flexible multibody system simulation based on nonlinear finite elements. This approach permits to better capture the effects of dynamic loading under service conditions. This process is challenging because most state-of-the-art studies in structural optimization have been conducted under (quasi-)static loading conditions or vibration design criteria and also because this ``fully integrated" optimization method is not a simple extension of static optimization techniques. The present paper proposes an approach based on a Level Set description of the geometry. This method leads to an intermediate level between shape and topology optimizations. Gradient-based optimization methods are adopted for their convergence speed. Numerical applications are conducted on the optimization of a connecting rod of a reciprocating engine with cyclic dynamic loading to show the feasibility and the promising results of this approach. [less ▲]

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See detailTopology optimization of compliant mechanisms: Application to vehicle suspensions.
Tromme, Emmanuel ULg; Lemaire, Etienne ULg; Duysinx, Pierre ULg

Conference (2011, November 14)

An efficient method to design a compliant vehicle suspension with only topology optimization.

Detailed reference viewed: 73 (13 ULg)
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See detailOptimization of flexible components in reciprocating engines with cyclic dynamic loading
Tromme, Emmanuel ULg; Bruls, Olivier ULg; Duysinx, Pierre ULg

in Samin, Jean-Claude; Fisette, Paul (Eds.) Proceedings of Multibody Dynamics 2011, Eccomas Thematic Conference: Brussels (Belgium), 4-7 juillet 2011 (2011, July 05)

This work considers the optimization of flexible components of mechanical systems modeled as multibody systems. This approach permits to better capture the effects of dynamic loading under service ... [more ▼]

This work considers the optimization of flexible components of mechanical systems modeled as multibody systems. This approach permits to better capture the effects of dynamic loading under service conditions. This process is challenging because most state-of-the-art studies in structural optimization have been conducted under static or quasi-static conditions. The formulation of the optimization problem for dynamic systems is fundamental; it is not a simple extension of static optimization. Naive implementation leads to fragile and unstable results. The present paper addresses the optimization of a connecting rod of a reciprocating engine with cyclic dynamic loading. Gradient-based methods are adopted for their convergence speed. Different formulations are investigated and compared. A first numerical application considers the optimization of the connecting rod regarding its mass and its elongation. After, another numerical application is carried on considering the stresses in the connecting rod. A conclusion on the influence of the optimization problem formulation is realized. [less ▲]

Detailed reference viewed: 60 (13 ULg)