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Publications (124)
To refine the prediction of the satellite harness dynamic behavior, this paper proposes an approach to characterize and identify the nonlinearities of the harness to enrich its dynamic model. In that regard, the characterization process based on several simple experimental tests is first detailed. The nonlinear properties of the cable harness are t...
This study examines the potential of elongated periodic three-dimensional lattice structures for the design of vibration filters using so-called absolute band gaps. These filters are generally obtained by modifying the total stiffness of the structure, which decreases the propagation velocity of all wave polarisations. With a view to optimisation,...
Identification of flutter margins in modern aeroelastic systems is a challenging task due to increased nonlinearities in novel designs, which can result in instabilities occurring below the linear flutter speed. These instabilities pose a significant risk as they may involve multiple stable solutions, such as large-amplitude self-sustained oscillat...
Galloping is a self-excited vibration problem that structures immersed in fluid flow can experience. Due to its essential nonlinear phenomena, the structure exhibits limit cycle oscillations (LCOs), which, at high levels, can lead to failure of the systems. This work proposes an investigation of electromagnetic-enhanced Nonlinear Energy Sinks (NES-...
The aim of this article is to investigate the parameter sensitivity of the (Non-Linear) Unsteady Vortex Lattice Method-Vortex Particle Method [(NL-)UVLM-VPM] with Particle Strength Exchange-Large Eddy Simulations (PSE-LES) method on a lower Reynolds number rotor. The previous work detailed the method, but introduced parameters whose influence were...
A solution for passive aeroelastic control is presented and tested experimentally on a bidimensional wing setup. The solution consists of a flap integrated in the wing which acts as a secondary mass damper and absorbs energy when aeroelastic instability is encountered. This device is passive, which makes it safe in emergency cases and adds little m...
The application of nonlinear vibration absorbers in a variety of dynamic systems is attracting significant attention . The so-called nonlinear energy sink (NES) has the ability to provide high vibration attenuation in a broad frequency with robustness. However, the effectiveness of this device can be limited with the increase of excitation, as it m...
There is a lack of knowledge in the literature concerning Body Segment Inertial Parameters (BSIP) for children aged 4 to 15 years. Nevertheless, these data are fundamental for studying the dynamics of the healthy and pathological musculoskeletal system. One common method for obtaining BSIP is to use regression equations derived from anthropometric...
Nonlinear stability analysis plays a key role in the design and evaluation of dynamical systems. Model-based analysis methods require extensive calibration and computational resources. While data-driven methods might offer a solution to this challenge, they are limited to available data and fail to generalize. Incorporating physical information abo...
Localization of vibration due to energy localized redistribution over a structure is defined by the presence of unusually large displacement at some specific locations of the structure. This article proposes a new understanding of the localization phenomena that occur in many different fields. These fields range from structural dynamics in lumped o...
Nonlinear stability analysis plays a key role in the design and evaluation of dynamical systems. Model-based analysis methods require extensive calibration and computational resources. While data-driven methods might offer a solution to this challenge, they are limited to available data and fail to generalize. Incorporating physical information abo...
Aeroelastic systems are at risk of flutter instabilities which can lead to structural failure. Recently, an innovative design of nonlinear energy sink (NES) has been introduced to suppress flutter instabilities by adding a NES to the flap control surface as a nonlinear energy absorber resulting in a flap-NES. Optimal choice of flap-NES parameters,...
Flutter instabilities might lead to structural failure in aeroelastic systems. Recently, a flap control surface turned into a nonlinear energy absorber (flap-NES) has been introduced to suppress post-flutter oscillations. This nonlinear absorber not only benefits from aerodynamic damping but also acts in a broad range of frequencies. However, the p...
View Video Presentation: https://doi.org/10.2514/6.2022-3669.vid Nowadays, experimental analyses of fluid-structure interactions on flexible rotating blades are few widespread. For this purpose, an experimental rotor test bench for blades with variable flexibility is under development. Different sets of blades have been fabricated with different co...
This study presents a hybrid non-linear unsteady vortex lattice method-vortex particle method (NL UVLM-VPM) to investigate the aerodynamics of rotor blades hovering in and out of ground effect. The method is of interest for the fast aerodynamic prediction of helicopter and smaller rotor blades. UVLM models the vorticity along the rotor blades and n...
View Video Presentation: https://doi.org/10.2514/6.2022-0654.vid This paper proposes a methodology to design a Nonlinear Energy Sink (NES) to control passively the vibration of an unstable dynamic system. The passive device is composed of purely nonlinear stiffness (cubic stiffness), a linear damper and a mass attached directly to a simplified dyna...
View Video Presentation: https://doi.org/10.2514/6.2022-2456.vid In order to quantify the influence of cable harnesses on the dynamic behavior of a satellite structure, this paper aims to understand how a cable attached to a structure dynamically respond. In that regard, the present work proposes a dynamic model based on beam theory for attached sa...
Vibration absorbers are known for their use in vibration mitigation. In particular, nonlinear vibration absorbers have been of great interest for vibratory level reduction as they do not have to be tuned to the natural frequency of their supporting structure. In order to obtain satisfactory operations of the absorber (energy necessary for its activ...
In this paper, a passive vibration damping concept based on multifunctional materials was studied for thermoplastic composite structures. The synergy between piezoelectric and conductive particles brings a new contribution of energy dissipation based on the local transduction-dissipation phenomenon. While piezoelectric fillers ensure the conversion...
The unsteady aerodynamic and aeroelastic behavior of a 2D wing section with and without flap is analyzed with Theodorsen theory and Unsteady Vortex Lattice Method (low fidelity), Euler (medium fidelity) and Reynolds-Averaged Navier Stokes (high fidelity) methods. The aeroelastic studies are carried out for linear cases and non-linear structural con...
This paper focuses on the experimental validation of a new methodology for substitution of Liquid Hydrogen (LH2) on a simplified model of launcher cryogenic tank in vibration analysis by using pre-stressed grains as surrogate materials. The objective of the experiments presented here is to analyze the modal behavior of the (Tank and Granular materi...
Acoustic black hole (ABH) is a well-established phenomenon in the field of acoustic. It consists in confining the vibration in the structure edge by controlling its thickness profile. This paper aims to achieve acoustic black-hole-like phenomenon by implementing a profile gradient instead of a thickness variation. To accomplish this, a composite sa...
Vibrations can cause several damages in industrial applications, heavy machinery, vehicles, equipment , and tools. In order to dissipate energy in vibrating structures, damping systems are designed for given frequency ranges. Vibration-reducing materials (such as viscoelastic films) outwardly disperse energy, thereby reducing the amplitude and freq...
Graphene and carbon black have been dispersed in a high performance thermoplastic polymer, the poly(ether ketone ketone), to improve its electrical conductivity. The dispersion of graphene has a significant influence on the percolation threshold. A simple exfoliation protocol to obtain graphene monolayers has led to a significant decrease of the pe...
This article investigates the use of a recently developed fibrous core material to increase vibration damping in sandwich beams. The entangled cross-linked fibre (ECF) material is made of short carbon fibres cross-linked with epoxy resin. Dry friction between fibres provides energy dissipation when the material is deformed. Previous measurements on...
This paper evaluates the effects and effectiveness of a dynamic vibration absorber (DVA) designed for mitigation of unstable oscillations of helicopters when it is on the ground, i.e.: ground resonance phenomenon. For this purpose, firstly, a parametric analysis shows the stability charts obtained for helicopters without and with DVA as function of...
The objective of this paper is to understand and study the effect of morphological parameters on the shear stiffness of an entangled cross-linked fibrous material made with carbon fibres where some of the contacts are bonded by the epoxy resin. This current work presents a 3D finite element model using ABAQUS/Standard in order to characterize the m...
The design of vibration absorbers is a challenging task for complex real-life structures. Although several technological solutions have now reached maturity,
a need for better efficiency in terms of added mass, broadband frequency range and level of reduction requires the study of new ideas and concepts coming from nonlinear dynamics. In this paper...
The analysis of an entangled cross-linked fibrous material at low deformation is explored as way of predicting
the shear behaviour, especially the shear hysteresis. This paper presents a 3D finite element model to characterize
the carbon fibre network rigidified by epoxy cross-links. The morphology of the representative volume
element (RVE) is stud...
Nonlinear vibration absorbers, commonly referred to as Nonlinear Energy Sinks (NESs), have been the object of several theoretical and experimental studies over the past decade. This work illustrates the theoretical design and experimental realization of a Nonlinear Energy Sink coupled to an energy harvester. The mass of the Magnetic-Strung NES is a...
A new entangled cross-linked material was recently developed in order to present a new core material that can resolve the drawbacks of the honeycomb. The optimization of entangled carbon fibres requires a deep understanding of the influence of the parameters of a fibre network on its macroscopic behaviour. This paper presents a 3D finite element mo...
In this paper, the dynamics of a system composed of a harmonically forced single-degree-of-freedom linear oscillator coupled to a vibro-impact nonlinear energy sink (VI-NES) is experimentally investigated. The mass ratio between the VI-NES and the primary system is about \(1\%\). Depending on the external force’s amplitude and frequency, either a s...
Lead-free piezoelectric nanocomposites based on poly(ether ketone ketone) (PEKK) and sodium niobate (NaNbO3) particles were elaborated. The presence of submicronic particles does not influence the thermal stability of the matrix so that no degradation phenomenon is observed before 500 °C. The conservative mechanical modulus G′ increases linearly wi...
The objective of this paper is to characterize and model the vibration behaviour of entangled carbon fibres cross-linked with epoxy resin. The material is tested in shear, in a double lap configuration. Experimental testing is carried out for frequencies varying from 1 Hz to 80 Hz and for shear strain amplitudes ranging from 5·10−4 to 1·10−2. Measu...
Designing innovative solutions for future aircraft is one the concerns of aeronautical engineers. Among the studied technologies, Counter Rotating Open Rotor (CROR) propeller technologies are appearing as a promising, though highly challenging, alternative solution to Ultra High Bypass Ratio (UHBR) engines. Amongst these challenges, the interaction...
In this work the dynamics of a Vibro-Impact Nonlinear Energy Sink (VI-NES) is experimentally investigated via a harmonically forced single-degree-of- freedom linear oscillator (LO) to which a VI-NES is attached. Depending on external force amplitude and frequency, either a Strongly Modulated Response (SMR) or a constant amplitude response (CAR) is...
The bending-torsion coupling for a sandwich beam is analysed from the static and vibrational point of view. Off-axis orientations in the skin and transverse graded core are proposed to perform the coupling. Solutions are first compared numerically from a static point of view using a complete beam theory. The natural frequencies and mode shapes are...
The performance of a linear tuned vibration absorber (LTVA) and a nonlinear energy sink (NES) for the vibrationcert mitigation of an unain linear primary system is investigated. An analytic tuning rule for the LTVA when the primary system contains uncertainty is derived. The behavior of the linear system coupled to the NES is analyzed theoretically...
In helicopter with hinged rotor, an unstable dynamic phenomenon known as ground resonance may occur, leading to the total destruction of the aircraft. The prediction of the stability boundary has been addressed for various helicopter configurations by using different methods. However, in order to develop control strategies for this phenomenon, the...
Recently, it has been demonstrated that a vibro-impact type nonlinear energy sink (VI-NES) can be used efficiently to mitigate vibration of a linear oscillator (LO) under transient loading. The objective of this paper is to investigate theoretically and experimentally the potential of a VI-NES to mitigate vibrations of an LO subjected to a harmonic...
This paper investigates the effect of a fibrous core material on the transient response of a sandwich structure. The core material studied is made of entangled carbon fibers cross-linked with epoxy resin. In order to understand its complex behavior, the material is characterized in shear oscillation, and the obtained shear-stress loops are describe...
The dynamic loads transmitted from the rotor to the airframe are responsible for vibrations, discomfort and alternate stress on components. A new and promising way to minimize vibration is to reduce dynamic loads at their source by performing an aeroelastic optimization of the rotor. This optimization uses couplings between the flapwise-bending mot...
A new hybrid nanocomposite for vibration damping has been elaborated. Ferroelectric lead zirconate titanate particles and carbon nanotubes are dispersed simultaneously in an engineering semi-crystalline thermoplastic matrix by an extrusion processing. Ferroelectric particles have been made piezoelectric once incorporated into the polymer matrix thr...
In helicopters with hinged blades an unstable dynamical phenomenon known as ground resonance may occur during take-off and landing and lead to the total destruction of the aircraft. Predicting the phenomenon is necessary to determine the stability of periodical equations of motion. The instability boundaries can be easily obtained for isotropic rot...
In this paper, the dynamic response of a harmonically forced linear oscillator (LO) strongly coupled to a nonlinear energy sink (NES) is investigated both theoretically and experimentally. The system studied comprises an LO with an embedded, purely cubic NES. The behavior of the system is analyzed in the vicinity of 1 : 1 resonance. The complexific...
In this paper, the use of entangled cross-linked fibers as core material in vibrating sandwich beams is investigated. The aim is to analyze the effect of this specific core material in terms of damping. The dynamic shear properties of the material are first studied experimentally. The shear modulus is shown to decrease with increasing shear strain...
The dynamic loads transmitted from the rotor to the airframe are responsible for vibrations, discomfort and alternate stress of components. A new and promising way to minimize vibration is to reduce dynamic loads at their source by performing an aeroelastic optimization of the rotor.
This optimization is done thanks to couplings between the flapwis...
Recently, it has been demonstrated that a Vibro-Impact type Nonlinear Energy Sink (VI-NES) can be used efficiently to mitigate vibration of a Linear Oscillator (LO) under transient loading. In this paper, the dynamic response of an harmonically forced LO, strongly coupled to a VI-NES is investigated theoretically and experimentally. Due to the smal...
This paper presents the interest of an original absorber of vibration in order to reduce chatter vibration in turning process. The device is composed of a linear oscillator corresponding to a flexible cutting tool subject to chatter strongly coupled to a Nonlinear Energy Sink (NES), with purely cubic stiffness. The novelty of this work is the use o...
The aim of this study is to provide a structural damping solution for space applications to enhance mission performance of honeycomb structures. Classical particle dampers are enclosures partially filled with small metallic or glass spheres, attached to a vibrating structure. The induced damping mechanism is mainly due to frictional losses and coll...
Operational modal analysis (OMA) techniques enable the use of in-situ and uncontrolled vibrations to be used to lead modal analysis of structures. In reality operational vibrations are a combination of numerous excitations sources that are much more complex than a random white noise or a harmonic. Numerous OMA techniques exist like SSI, NExT, FDD a...
A particle damper can be defined as a container partially filled with particles (eg sand, beads), which is attached to or within a vibrating structure. There is a need for a methodology to design and to qualify a "soft" damping particle adapted to space applications. The aim of this work is to make 'space useable' damping particles without degradin...
This paper presents a stability robustness analysis of the helicopter ground-resonance phenomenon. By using the lifting procedure the uncertain linear-time-periodic model of the helicopter is transformed into an augmented uncertain linear-time-invariant model that allows the application of mu-analysis tools. The lifting procedure involves a periodi...
Recent works study the ground resonance in helicopters under the aging effects. Indeed, the blades lead-lag stiffness may vary randomly with time and be different from each other (i.e.: anisotropic rotor). The influence of stiffness dissimilarities between blades on the stability of the ground resonance phenomenon is determined through numerical in...
In this paper, the dynamic response of a harmonically forced Linear Oscillator (LO) strongly coupled to a Nonlinear Energy Sink (NES) is investigated theoretically and experimentally. The system studied comprises a linear oscillator subject to an imposed displacement with an embedded, purely cubic, NES. The behavior of the system is analyzed in the...
The present work is aimed at verifying the influence of high asymmetries in the variation of in-plane lead-lag stiffness of one blade on the ground resonance phenomenon in helicopters. The periodical equations of motions are analyzed by using Floquet's Theory (FM) and the boundaries of instabilities predicted. The stability chart obtained as a func...
This paper investigate the different response regimes of a cutting tool on a lathe strongly coupled to a nonlinear energy sink. The equations of motion are analysed via the method of multiple scales. Condition of elimination of secular terms permit to derive equation of the slow invariant manifold (SIM) and the behavior of the system has been expla...
This paper explores analytically the nonlinear dynamic behavior of rotors. Coupled nonlinear equations of motion are formulated using Hamilton's principle. The rotor model is composed of a rigid disk and a flexible shaft which is characterized as a beam of circular cross section. Various influences are taken into account like the effect of higher o...
Dynamic behavior of the inner ear is very remarkable. However, due to the complexity of in vivo experimentations, still some aspects of physiological functions need to be investigated. This paper focuses on the comparison between an experimental setup reproducing the passive behaviour of the inner ear and the corresponding modelling. As in the inne...
Inner ear is a remarkable multiphysical system and its modelling is a great challenge. The approach used in this paper aims to reproduce physic with a realistic description of the radial cross section of the cochlea. A 2D?section of the organ of Corti is fully described. Wavenumbers and corresponding modes of propagation are calculated taking into...
An analysis of linear and nonlinear dynamics of rotors is presented taking into account the shear effects. The nonlinearity arises due to the consideration of large deformations in bending. The rotor system studied is composed of a rigid disk and a circular shaft. In order to study the combined effect of rotary inertia and shear effects the shaft i...
Helicopter ground resonance is an unstable dynamic phenomenon which can lead to the total destruction of the aircraft during take-off or landing phases. The earliest research in this domain was done by Coleman and Feingold around the 60's decade. The prediction of the instability was possible by using classical procedures once the rotor was conside...
The relationship which links the normal vibration occuring during the sliding of rough surfaces and the nominal contact area is investigated. Two regimes are found. In the first one, the vibrational level does not depend on the contact area while in the second one, it is proportional to the contact area. A theoretical model is proposed. It is based...
A mathematical model incorporating the higher order deformations in bending is developed and analyzed to investigate the nonlinear dynamics of rotors. The rotor system considered for the present work consists of a flexible shaft and a rigid disk. The shaft is modeled as a beam with a circular cross section and the Euler Bernoulli beam theory is app...
Impact resistance of different types of composite sandwich beams is evaluated by studying vibration response changes (natural frequency and damping ratio). This experimental works will help aerospace structural engineer in assess structural integrity using classification of impact resistance of various composite sandwich beams (entangled carbon and...
In the present works, we examine experimentally and theoretically the dynamic behavior of linear oscillator strongly coupled to a nonlinear energy sink under external periodic forcing. The nonlinear oscillator has a nonlinear restoring force realized geometrically with two linear springs that extend axially and are free to rotate. Hence, the force-...
This paper presents a practical framework and its applications of motion tracking algorithms applied to structural dynamics. Tracking points (“features”) across multiple images is a fundamental operation in many computer vision applications. The aim of this work is to show the capability of computer vision (CV) for estimating the dynamic characteri...
Helicopter ground resonance is an unstable dynamic phenomenon which can lead to the total destruction of the aircraft during take-off or landing phases. Studies have been developed by researchers which considered a simplified mathematical model. With the goal of further comprehend the phenomenon, predictions of unstable motions are done and compare...
Serpentine belt drives are often used in front end accessory drive of automotive engine. The accessories resistant torques are getting higher within new technological innovations as stater-alternator, and belt transmissions are always asked for higher capacity. Two kind of tensioners are used to maintain minimum tension that insure power transmissi...
This paper deals with experimental study and with understanding via a finite number of degrees of freedom model of the vibrations of an inclined cable linked to a continuous beam. This is a simplified version of deck and cable of a bridge. External excitation is exerted on the beam. The cable attached to the end of the beam is submitted to a vertic...
This paper presents a method for choosing the most appropriate contact model from several models, by comparing their efficiency for predicting hysteretic behaviour in different applications. The first part describes an application for a belt tensioner used for automotive engines. The second part concerns an academic application and focuses on a sim...
