References of "Denoël, Vincent"
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See detailPerturbation methods for the determination of the statistical response of nonlinear Volterra systems
Denoël, Vincent ULg; Carassale, Luigi

in Proceedings of the Eurodyn 2014 Conference (2014)

The point-like quasi-steady aerodynamic loading in a turbulent flow is formally expressed as a function of the squared relative velocity between the fluid and the investigated structure. The three major ... [more ▼]

The point-like quasi-steady aerodynamic loading in a turbulent flow is formally expressed as a function of the squared relative velocity between the fluid and the investigated structure. The three major terms governing the low-order statistics of the response are known to be related to the average loading, the linear turbulent loading and the aerodynamic damping. The three other terms in the loading, namely the quadratic turbulence term, the parametric velocity feedback term and the squared velocity term, may significantly affect the higher order statistical cumulants of the response. These latter two sources of fluid-structure interaction are usually disregarded, by lack of efficient simulation tools, except a Monte Carlo simulation of the nonlinear equation. In this paper, we provide a formal analysis of the complete nonlinear model, including thus all six terms, but mainly focusing on the importance of the two nonlinear coupling terms of the loading. Closed form solutions of the response are derived for a second-order Volterra model of this problem, under the assumption of different timescales in the loading and in the structural behavior. Two major outcomes of the analysis are, on the one hand, that the squared structural velocity term has no influence on the cumulants of the response up to order 4 and, on the other hand, that the parametric velocity feedback acts as a reduction of the non Gaussianity of the response. [less ▲]

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See detailA Fast Newton-Raphson Method in Stochastic Linearization
Canor, Thomas ULg; Blaise, Nicolas ULg; Denoël, Vincent ULg

in Proceedings of the Ninth International Conference on Structural Dynamics (2014)

Owing to its accessible implementation and rapidity, the equivalent linearization has become a common probabilistic approach for the analysis of large-dimension nonlinear structures, as encountered in ... [more ▼]

Owing to its accessible implementation and rapidity, the equivalent linearization has become a common probabilistic approach for the analysis of large-dimension nonlinear structures, as encountered in earthquake and wind engineering. It consists in replacing the nonlinear system by an equivalent linear one, by tuning the parameters of the equivalent system, in order to minimize some discrepancy error. Consequently classical analysis tools such as the spectral analysis may be reconditioned to approximate the solution of structures with slight to moderate nonlinearities. The tuning of the equivalent parameters requires the solution of a set of nonlinear algebraic equations involving integrals. It is typically performed with the fixed-point algorithm, which is known to behave poorly in terms of convergence. We therefore advocate for the use and implementation of a Newton-Raphson approach, which behaves much better, even in its dishonest formulation. Unfortunately, this latter option requires the costly construction of a Jacobian matrix. In the approach described in this paper, this issue is answered by introducing a series expansion method that provides a fast and accurate estimation of the residual function (whose solution provides the equivalent parameters) and a fast and approximate estimation of the Jacobian matrix. An illustration demonstrate the good accuracy obtained with the proposed method. [less ▲]

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See detail3D analysis of gait using accelerometer measurements
Boutaayamou, Mohamed ULg; Schwartz, Cédric ULg; Stamatakis, Julien et al

Scientific conference (2013, November 07)

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See detailAn efficient formulation for the simulation of elastic wave propagation in 1-dimensional collinding bodies
Depouhon, Alexandre ULg; Detournay, Emmanuel; Denoël, Vincent ULg

in Proceedings of the 11th International Conference on Vibration Problems (2013, September 09)

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See detailA drifting impact oscillator with periodic impulsive loading: Application to percussive drilling
Depouhon, Alexandre ULg; Denoël, Vincent ULg; Detournay, Emmanuel

in Physica D: Nonlinear Phenomena (2013), 258(0), 1--10

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See detailVibrations of cables with bending stiffness by an asymptotic approach
Canor, Thomas ULg; Denoël, Vincent ULg

in Zingoni, Alphose (Ed.) Fifth International Conference on Structural Engineering, Mechanics & Computation, Cape Town, 1-4 September 2013 (2013, September)

Vibrations of cables with a small bending stiffness concerns many engineering applications such as the fatigue assessment of stay cables. With the finite element (FE) method, the analysis can be performed ... [more ▼]

Vibrations of cables with a small bending stiffness concerns many engineering applications such as the fatigue assessment of stay cables. With the finite element (FE) method, the analysis can be performed with nonlinear truss elements, but bending effects are not taken into account. Otherwise, beam elements can be used, but the smallness of the bending stiffness may lead to numerical instability and mediocre results in boundary regions. In this context, the paper presents an alternative method to calculate the time evolution of the profile of bending moments in boundary layers of cables, avoiding heavy FE analysis. The developments combine the theory of vibrations of extensible rods with asymptotic methods. The equations are decoupled between the slow dynamics of the boundary regions and the fast dynamics of the span. Then, a composite solution is constructed by means of a matched asymptotic procedure. [less ▲]

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See detailEquivalent static wind loads for structures with non-proportional damping
Blaise, Nicolas ULg; Canor, Thomas ULg; Denoël, Vincent ULg

in Zingoni, A (Ed.) Fifth International Conference on Structural Engineering, Mechanics & Computation (2013, September)

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See detailEulerian Formulation for an Extensible Elastic Rod
Huynen, Alexandre ULg; Detournay, Emmanuel; Denoël, Vincent ULg

in Proceedings of the Fifth International Conference on Structural Engineering, Mechanics and Computation (2013, September)

This paper reformulates the governing equations of an extensible elastic rod by reference to a given spatial curve. This Eulerian formulation is motivated by the need to solve efficiently the constrained ... [more ▼]

This paper reformulates the governing equations of an extensible elastic rod by reference to a given spatial curve. This Eulerian formulation is motivated by the need to solve efficiently the constrained elastica problem encountered in many medical and engineering applications, in which a thin rod is inserted in a tortuous conduit. The Eulerian reformulation of the equations hinges on the restatement of the rod local equilibrium in terms of derivatives with respect to the curvilinear coordinate associated with the reference curve and the description of the rod deflection as a perturbation of this curve. The originality of the proposed formulation lays in the axially unconstrained character of the resulting system such that the determination of the rod configuration between two fixed points reduces to the resolution of a classical boundary value problem. [less ▲]

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See detailOn a modified bilinear law to model bit/rock interaction in percussive drilling
Depouhon, Alexandre ULg; Denoël, Vincent ULg; Detournay, Emmanuel

in Proceedings of the Nonlinear Dynamics in Engineering Conference (2013, August 21)

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See detailReference populations for shoulder studies should be selected carefully
Schwartz, Cédric ULg; Denoël, Vincent ULg; Bruls, Olivier ULg et al

Conference (2013, August 06)

To assess various shoulder pathologies / treatments, non pathological populations are often used as references. However, some factors may influence significantly the scapular kinematics within a healthy ... [more ▼]

To assess various shoulder pathologies / treatments, non pathological populations are often used as references. However, some factors may influence significantly the scapular kinematics within a healthy population and consequently alter the final kinematic evaluation. Results of 3D shoulder assessment found in this study show that small (≈5°) but significant differences exist between gender and between the dominant and non-dominant arms. Therefore the populations used for referential data should be selected carefully. [less ▲]

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See detailPrincipal static wind loads
Blaise, Nicolas ULg; Denoël, Vincent ULg

in 6th Proceedings of European-African Conference on Wind Engineering (2013, July 07)

The concept of static wind load is widely used in practice for structural wind design. In this context, this paper assesses the envelope reconstruction problem stated as follows: find the best set of ... [more ▼]

The concept of static wind load is widely used in practice for structural wind design. In this context, this paper assesses the envelope reconstruction problem stated as follows: find the best set of static loadings that is optimum to reproduce by static analyses, the envelope values of structural responses resulting from a formal buffeting dynamic analysis. A solution was recently derived by means of Principal Static Wind Loads which are well-suited for this problem. The concept is illustrated with a large stadium roof and the accuracy of the envelope reconstruction is analysed. [less ▲]

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See detailUncoupled spectral analysis with non-proportional damping
Canor, Thomas ULg; Blaise, Nicolas ULg; Denoël, Vincent ULg

in Proceedings of the European-African Conference on Wind Engineering (2013, July 07)

The use of normal modes of vibration in the analysis of structures with non-proportional damping reduces the number of governing equations, but does not decouple them. A common practice consists in ... [more ▼]

The use of normal modes of vibration in the analysis of structures with non-proportional damping reduces the number of governing equations, but does not decouple them. A common practice consists in decoupling the equations by disregarding the off-diagonal elements of the modal damping matrix. This paper proposes a method based on the asymptotic expansion of the modal transfer matrix to take into account the modal coupling in Gaussian spectral analysis. First, the mathematical background is introduced, then the relevance of the method is illustrated within the context of the analysis of a large and real structure submitted to wind loadings. [less ▲]

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See detailEquivalent static wind loads for structures with non-proportional damping
Blaise, Nicolas ULg; Canor, Thomas ULg; Denoël, Vincent ULg

in Proceedings of the 11th International Conference on Recent Advances in Structural dynamics (2013, July)

In current practice, wind structural design is often carried out using the concept of equivalent static wind loads. The main characteristic of such loadings is to reproduce, with static analyses, the same ... [more ▼]

In current practice, wind structural design is often carried out using the concept of equivalent static wind loads. The main characteristic of such loadings is to reproduce, with static analyses, the same extreme structural responses as those resulting from a formal buffeting analysis. This paper proposes a method for the computation of equivalent static wind loads for structures with slight non-proportional damping in a modal framework. Because of the smallness of the out-of diagonal terms, this method is based on recent developments related to asymptotic expansion of the modal transfer matrix of such structures. As a main benefit, the static loading is described as a perturbation of the equivalent loading that would be obtained for the uncoupled system. The main contribution of this paper is to formalize the expression of the correction terms resulting from the non-proportionality of damping. The method is presented with a detailed illustrative example. [less ▲]

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See detailValidation of an accelerometer-based approach to quantify gait events
Boutaayamou, Mohamed ULg; Schwartz, Cédric ULg; Stamatakis, Julien et al

Poster (2013, June)

Researchers rarely provide solid performance and validation information about their acceleometer-based approaches to human gait analysis. We present here a novel signal processing and analysis algorithm ... [more ▼]

Researchers rarely provide solid performance and validation information about their acceleometer-based approaches to human gait analysis. We present here a novel signal processing and analysis algorithm that automatically extracts four consecutive fundamental events of walking: heel strike (HS), toe strike (TS), heel off (HO), and toe off (TO). In addition, we validate this accelerometer-based technique by comparing these extracted gait events with those obtained by a kinematic 3D analysis system and a force plate, used as gold standards. [less ▲]

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See detailTransient Fokker-Planck-Kolmogorov equation solved with smoothed particle hydrodynamics method
Canor, Thomas ULg; Denoël, Vincent ULg

in International Journal for Numerical Methods in Engineering (2013), 94(6), 535553

Probabilistic theories aim at describing the properties of systems subjected to random excitations by means of statistical characteristics such as the probability density function (pdf). The time ... [more ▼]

Probabilistic theories aim at describing the properties of systems subjected to random excitations by means of statistical characteristics such as the probability density function (pdf). The time evolution of the pdf of the response of a randomly excited deterministic system is commonly described with the transient Fokker-Planck-Kolmogorov equation (FPK). The FPK equation is a conservation equation of a hypothetical or abstract fluid, which models the transport of probability. This paper presents a generalized formalism for the resolution of the transient FPK equation using the well-known mesh-free Lagrangian method, Smoothed Particle Hydrodynamics (SPH). Numerical implementation shows notable advantages of this method in an unbounded state space: (i) the conservation of total probability in the state space is explicitly written, (ii) no artifact is required to manage far- eld boundary conditions , (iii) the positivity of the pdf is ensured and (iv) the extension to higher dimensions is straightforward. Furthermore, thanks to the moving particles, this method is adapted for a large kind of initial conditions, even slightly dispersed distributions. The FPK equation is solved without any a priori knowledge of the stationary distribution; just a precise representation of the initial distribution is required. [less ▲]

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See detailL'apport de l'analyse biomécanique 3-D dans les stratégies préventives à partir de 2 exemples
Schwartz, Cédric ULg; Croisier, Jean-Louis ULg; Tubez, François ULg et al

in Julia, M; Croisier, Jean-Louis; Perrey, S (Eds.) et al Prévention des troubles musculo-squelettiques chez le sportif (2013)

De nouveaux outils de mesure permettent de quantifier la cinématique et la dynamique articulaire fonctionnelle des athlètes (systèmes optoélectroniques 3D, plateforme de forces, électromyographie, …). Ces ... [more ▼]

De nouveaux outils de mesure permettent de quantifier la cinématique et la dynamique articulaire fonctionnelle des athlètes (systèmes optoélectroniques 3D, plateforme de forces, électromyographie, …). Ces données sont importantes dans le sens où elles donnent à l’équipe médicale et sportive des informations objectives sur le geste du sportif dans sa pratique réelle. Elles favorisent la compréhension et l’amélioration de la performance ainsi que la prévention lésionnelle et la détection de situations à risque. Dans le cadre d’un suivi longitudinal des sportifs, ces mesures sont intéressantes pour mettre en place des critères objectifs et spécifiques à l’athlète de retour sur le terrain après une blessure. Ce document a pour objectif de présenter les principaux outils disponibles dans les laboratoires de biomécanique et d’illustrer leurs utilisations à travers 2 exemples : l’influence de la raideur de l’épaule sur la mobilité de l’épaule et l’analyse cinématique du service au tennis. [less ▲]

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See detailPrincipal static wind loads
Blaise, Nicolas ULg; Denoël, Vincent ULg

in Journal of Wind Engineering & Industrial Aerodynamics (2013), 113

In current wind design practice, static wind loads are usually defined to obtain, by simple static analyses, the extreme values of any structural response that would be formally obtained with a strict ... [more ▼]

In current wind design practice, static wind loads are usually defined to obtain, by simple static analyses, the extreme values of any structural response that would be formally obtained with a strict dynamic buffeting analysis. The minimum and maximum values that may reach any response define the envelope. Equivalent static wind loads (ESWLs) allow to recover extreme responses in the envelope. As a first objective, this paper formalizes a general method to determine ESWL, in a nodal basis, by extending the concept of load-response correlation, which is only valid in the background range. The general method, the displacement-response-correlation (DRC) method, covers the background and resonant contributions of the considered response. As a second objective, the paper addresses the problem of building a set of static wind loads that adequately reconstructs the envelopes of responses. The concept of principal static wind loads (PSWL) is introduced to form a reduced basis of representative loads well-suited for envelope reconstruction. Its optimality is demonstrated both analytically and with a detailed illustrative example. [less ▲]

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See detailElements de processus stochastiques
Denoël, Vincent ULg

Learning material (2013)

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See detailDynamic Computation and Design of a World’s Record Death-Ride
Denoël, Vincent ULg; Canor, Thomas ULg; Demanet, Johan

in Proceedings of the 4th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (2013)

A death-ride is a long cable anchored between two dead ends, allowing the crossing of wide valleys. Besides these mobility purposes, it is also operated in rescue operations, or simply for leisure. From a ... [more ▼]

A death-ride is a long cable anchored between two dead ends, allowing the crossing of wide valleys. Besides these mobility purposes, it is also operated in rescue operations, or simply for leisure. From a serviceability viewpoint, a death-ride design should offer a comfortable and/or enjoyable journey to the riders, which is typically expressed in terms of maximum velocity. From a strength viewpoint, a death-ride should be designed in order to safely withstand the cable self-weight, wind forces, the rider’s load and at last but not least, the initial tension in the cable. Actually, the tensioning operation is usually subtle. Indeed, in case of a loose cable, the rider may be stopped in the in-span sagging area. Conversely a too tight cable will generate large stresses but also large outlet velocity at the end of the ride. The design of a death-ride is a tradeoff between all these aspects. The paper presents the dynamic model that was used for the design of a 1.2km long death-ride, with an only 10-mm diameter, a constraint fixed in the very first stages of this project for compatibility reasons, with the existing equipment. This death-ride, built and used in May 2010 in a Grimp competition [1], has a world record of the longest death-ride in urban area. The structural part of the dynamic model is rather common, with a co-rotational description of the cable by means of a chain-like model [2]. An interesting feature, however, concerns the interaction between the rider and the cable. In fact, because the pulley is rolling on the cable, the position of the force acting on the cable, resulting from the ride, depends on the rider’s velocity, which itself depends on the cable inclination. This coupling is solved in a staggered manner, and the details of the algorithm are given in the full paper. In some limiting cases, a comparison with analytical solutions is also provided, where these analytical solutions are available [3]. Experimental validation and observation of the operated death-ride will also be presented. [less ▲]

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