Gaël Chevallier

• Professor
• Professor (Full) at University Bourgogne Franche-Comté

Vibroimpact absorption is a vibration attenuation strategy that consists of transferring the energy of a vibrating structure to high frequencies during impacts with a secondary oscillating mass. The energy transferred is dissipated, and the process thus generated is irreversible. The efficiency of a single absorber has been the subject of various e...

The Payne or Fletcher-Gent effect is a particular behavior occurring in viscoelastic materials containing fillers. It induces a nonlinear dependency of the viscoelastic storage modulus on the amplitude of the applied strain. This amplitude dependency must be taken into account in engineering applications as it does change the elastodynamic behavior...

This study presents a concept for a straightforward method to enhance the actuation performances of magneto‐active elastomer membranes. The concept is based on a characteristic magnetization pattern and offers a solution to two major difficulties in the actuation of thin and mechanically soft magnetic actuators: the localization of actuation forces...

Viscoelastic materials are widely utilized in engineering for their advantageous damping properties , which enable effective energy dissipation. They are also valued for their stiffness properties, particularly in the case of suspension design. The behavior of these materials is complex, making it challenging to accurately incorporate them into sim...

This paper investigates how to improve the performance of a classifier of tightening torque in bolted joints by applying transfer learning. The procedure uses vibration measurements to extract features and to train a classifier using a Gaussian Mixture Model (GMM). The key to enhancing the surrogate model for torque loss detection is considering th...

FE models to simulate aeroengines rotordynamics become more and more complex thanks to the improvement of computational resources. Numerical simulations for industrial scale applications are nevertheless expensive in terms of computational effort because of their size and the presence of nonlinearities. In many-query frameworks (sensitivity or reli...

FE models to simulate aeroengines rotordynamics become more and more complex thanks to the improvement of computational resources. Numerical simulations for industrial scale applications are nevertheless expensive in terms of computational effort because of their size and the presence of nonlinearities. In many-query frameworks (sensitivity or reli...

The major challenge in detecting the loss of tightening torque in bolted connections using indirect vibration measurements is the considerable variability and noise presented in the data. This issue is more complex, assuming a heterogeneous population of a set of bolted connections with incomplete data or unlabeled information, i.e., where only som...

This paper introduces a new concept for shape memory based on elastic forces and magnetically induced friction forces in composite materials consisting of magnetoactive elastomers (MAEs). Magnetic attraction forces between two MAEs generate a contact pressure at their interface and the friction allows to maintain stable deformed shapes of the so-ca...

The interpretation of unlabeled acoustic emission (AE) data classically relies on general-purpose clustering methods. While several criteria have been used in the past to select the hyperparameters of those algorithms, few studies have paid attention to the development of dedicated objective functions in clustering methods able to cope with the spe...

Vibro-impact (VI) phenomenon can be used in vibration absorbers to reduce low frequency vibrations on a fast time scale. VI absorbers are effective on a wide range of frequency, they are also known to be robust and insensitive to temperature changes, and they do not rely on visco-elastic materials. This solution offers very interesting and promisin...

Finite element models representing industrial scale turbo-machines have reached today a very large number of degrees of freedom. The large size of these models requires the use of reduced order modelling to make the simulations computationally affordable. However, the physical characteristics (i.e. modes shapes and natural frequencies) of a rotatin...

The design of complex engineering structures largely relies on computational intelligence in the form of science-based predictive models to support design decisions. This approach requires modeling and manufacturing uncertainties to be accounted for explicitly and leads to an inescapable trade-off of performance for robustness. To remedy this situa...

Tuned Mass Dampers (TMD) are passive devices well-known to mitigate vibrations thanks to the principle of vibration absorption. They consist of a mass, a spring and a damper whose frequency is tuned to a critical frequency of a master structure in order to generate the expected energy transfer. As these devices require a very fine tuning to be effi...

In this work we present a new concept for friction damping which is based on the permanent magnetization and the flexibility of magnetoactive elastomers (MAE). The concept is called “magnetofriction” and is studied on a sandwich structure in the present work. The assembled structure consists of a MAE core and ferromagnetic skins. Due to the magneti...

Observing the loss of tightening torque using modal parameters is challenging due to the variability and nonlinear effects in bolted joints. Thus, this paper proposes a combined application of two probabilistic machine learning methods. First, a Gaussian mixture model (GMM) is learned using estimated natural frequencies, assuming the tightening tor...

The dataset presented in this work, called ORION-AE, is made of raw AE data streams collected by three different AE sensors and a laser vibrometer during five campaigns of measurements by varying the tightening conditions of two bolted plates submitted to harmonic vibration tests. With seven different operating conditions, this dataset was designed...

This paper presents a new concept for passive vibration mitigation in sandwich structures. The test structure in the present work is composed of permanently magnetized MagnetoActive Elastomers (MAEs) and ferromagnetic sheets representing the core and the skins of the sandwich respectively. The magnetic forces which develop between the core and the...

Manufacturing processes have evolved with time from skilled craftmanship where unique objects are created one at a time, to mass production where standardized products are manufactured in large quantities at lower cost. While handmade products vary in quality depending on the craftsperson’s expertise, they are generally considered to be higher qual...

The design of complex engineering structures largely relies on computational intelligence in the form of science-based predictive models to support design decisions. This approach requires modeling and manufacturing uncertainties to be accounted for explicitly and leads to an inescapable trade-off of performance for robustness. To remedy this situa...

This paper proposes a new lap-joint configuration, the so-called Orion beam. The new setup is composed of two thin beams connected by three bolted joints with contact patches on each connecting bolt. The Orion beam suggests an assembly configuration, in which there are bolts dedicated to ''static" functions to guarantee structural integrity and tho...

Monitoring loosening in jointed structures during operation is challenging because contact and friction, in bolted joints, induce a nonlinear stochastic behavior. The purpose of work is to provide datasets from acoustic emission (AE) sensors obtained during harmonic vibration tests. These datasets have been used to validate the development of a new...

This data article comprises experimental data to investigate the nonlinear dynamic behavior of the Orion beam structure, which consists of two duraluminum beams assembled by bolted joints. To retain contact on a small area between both beams, this new lap-joint configuration proposes contact patches at each bolt connection. The Orion beam suggests...

The interpretation of unlabeled acoustic emission (AE) data classically relies on general-purpose clustering methods. While several external criteria have been used in the past to select the hyperparameters of those algorithms, few studies have paid attention to the development of dedicated objective functions in clustering methods able to cope wit...

Vibro-impact (VI) based control strategies exploit non-linear phenomena occurring during impacts between oscillating masses and vibrating structures to mitigate vibrations. They are known to be effective on a wide frequency range, in harsh environnement, and they are eco-friendly in comparison to some visco-elastic polymers used for the same applic...

Magneto-rheological elastomers belong to the class of smart materials whose mechanical properties can be controlled by an external magnetic field. These materials can be integrated into mechatronic systems and submitted to multiple loadings such as temperature, mechanical stress and magnetic field. Thus, the present work is dedicated to the develop...

This paper proposes a procedure to identify a stochastic Bouc-Wen model for describing the dynamics of a structure assembled by bolted joints considering vibration data. The proposed identification approach is expressed into a Bayesian framework to take into account the data fluctuations related to uncertainties in the measurement process. The cali...

Acoustic Emission (AE) is a non-destructive technique suitable for monitoring structural damages in complex systems. Interpretation of AE data is generally made by an unsupervised learning approach called clustering. A clustering method divides a dataset into different groups called clusters, which are expected to have a physical interpretation in...

Presentation at e-ICoEV 2020

The acoustic and vibratory analysis represent an essential research axis in the automotive industry because these phenomena directly affect the appreciation of the customer when using a vehicle. Indeed, the combustion engine represents the main source of mechanical energy but it generates an acyclic torque because of the explosions. This acyclism i...

Rotors of asynchronous machines can be subjected to risk of failure due to vibratory fatigue. This is caused by the way electric motors are powered. Pulse Width Modulation (PWM) is the control strategy of the traction chain. This signal is composed by a fundamental and numerous harmonics of voltage and current that induce harmonics on the torque si...

This study concerns a magnetorheological elastomer (MRE) consisting of a magnetically hard powder and a stiff polymer matrix, so called STH–MRE. This material exhibits some strong constitutive differences with the behavior of MRE based on soft polymer matrix and magnetically hard powder (SOH–MRE). This paper presents a manufacturing process for suc...

In this work, a smart composite structure with damping and stiffness control ability is proposed. The multilayered arrangement has a shape memory core, whose damping and stiffness are tuned by temperature control. The structure is divided in several zones, each of them can be heated in real time using temperature regulation to reach the expected me...

This paper studies a new type of smart metamaterial consisting of piezoelectric actuators and digital synthetic impedance circuits (digital circuits). The digital circuit contains a micro-controller. By programming the micro-controller, the circuit can establish any desired impedance between the terminals of the connected piezoelectric patch, there...

This article outlines the development of a Project-Based Learning (PBL) course for first-year students at SUPMECA, a French engineering school. In the French Grande Ecole system, engineering students are recruited after a two-year preparation, which is equivalent to the first two years of a degree course. The objective of this form of pedagogy is t...

L'étude des roulements à billes de précision nécessite le développement de modèles prédictifs. Cependant, la plupart des codes de calcul ne prennent pas en compte les défauts de forme des bagues. Ils ne permettent donc pas de comprendre/prédire l'impact des défauts sur le comportement du roulement (chargement/décollement des billes, défauts de poin...

Smart metamaterials consisting of piezoelectric materials are promising structures with new functionalities. Previous studies usually use shunt circuitry composed of analog elements or active feedback control strategies with sensors and actuators to control the piezoelectric materials. The shunt circuitry is simple since it uses the same piezoelect...

Viscoelastic materials are commonly used for passive treatment in many applications. They exhibit a specific behavior depending on frequency and temperature, and thus damping performances can strongly vary in an uncertain environment for which these materials can be used far from their optimal nominal value. The problem studied in this paper is the...

In this paper, an adaptive phononic crystal slab based on the combination of metallic parts and highly dissipative polymeric interfaces is designed. Cylindrical pillars are composed of shape memory polymer and aluminium deposited periodically on the aluminium slab. The mechanical properties of the polymer depend on both temperature and frequency an...

This chapter deals with the damping caused by friction in joints. A new test bench is presented and justified by comparisons made with devices described in the literature. The purpose of this academic bench is to measure the damping induced by partial slip and friction in a planar joint. A new method for the so-called stopped-sine excitation was de...

The viscoelastic properties of tBA/PEGDMA, which is a Shape Memory Polymer (SMP), were characterized over wide bands of frequency and temperature. The continuity of the viscoelastic properties identified according to the frequency, the temperature, the loading mode and the test scale was assessed. Seven experimental methods were used, from quasi-st...

Friction modeling is essential in a vast amount of engineering applications. In this paper Mindlin contact friction model, a Masing rule compliant model, is manipulated in order to find a correlation with Dahl dynamic friction model, a Masing rule not compliant model. The resulting equations are then numerically compared and the correlation demonst...

The evaluation of damping in the assembled structures presents a real challenge. Indeed, because of the nonlinear behavior of the dissipation and their localization in interfaces, the equations of motion of a dynamic system involve coupling terms. These coupling terms are generally neglected, in engineering applications, by the community because of...

The lightness of the space and aerospace structures causes their vulnerability to vibrations. The cold temperatures do not allow using polymer materials. Active and semi-active control using piezos embedded on the structure can be used efficiently instead of polymers but they induce energy consumption. Friction damping is less efficient but it does...

The lightness of the space and aerospace structures causes their vulnerability to vibrations. The cold temperatures do not allow using polymer materials. Active and semi-active control using piezos embedded on the structure can be used efficiently instead of polymers but they induce energy consumption. Friction damping is less efficient but it does...

Due to their lightness, the aerospace structures are vulnerable to vibrations. Their amplitudes need to be mitigated through damping devices. The aim of this paper is to control the tightening force of a bolted joint in order to improve the vibration reduction. The work focuses on a single vibration mode modeled by two degrees of freedom coupled wi...

This paper deals with the use of piezoelectric patches for nonlinear dynamic identification. The patches are glued on the structure to identify amplitude-dependent damping and natural frequency; their positions are defined in order to perform the excitation concentrated on the first bending mode. Their locations on the structure allow to perform “s...

The challenge of this study is the evaluation of the damping in structures with localised dissipations. Proportional damping is usually assumed even if it provides inaccurate results when compared with damping of real structures. Bearing this in mind, we present in this research a thorough study which was performed to investigate the validity domai...

La problématique de l'amortissement dans les structures assemblées présente un réel challenge. L'amortissement est généralement modélisé sous l'hypothèse de Rayleigh ou de Caughey même si la dissipation n'est pas répartie de façon uniforme sur toute la structure. L'amortissement proportionnel ou bien de Rayleigh, condition nécessaire, est exprimé c...

This paper presents a novative method for gradient-based optimization with regard to CAD parameters. This method allows to respect manufacturing, design and surface quality rules, particularly required in computational fluid dynamics (CFD). It can be used with any objective function available in adjoint solvers (both in structural and CFD). To prov...

Modal damping estimation errors can be introduced when using assumptions such as proportional damping or a diagonal generalized matrix of localized dissipation at interfaces [1]. Previous work has studied the estimation of modal damping in bolted joints using many methods [2, 3]. One such method, used in this work, is the iterative energetic method...

This paper describes a method aimed at producing reduced order models in state-space form for speeding up the transient thermal simulation of mechatronics products. Designed in a non-intrusive framework, this method is implemented as an offline tool that post-processes the inputs and outputs of a detailed reference model considered as a black box....

This work describes an automatic method for removing modulated sinusoidal components in signals. The method consists in using the Optimized Spectral Kurtosis for initializing Series of Extended Kalman Filters. The first section is an introduction to vibration applications with Kalman Filters and modulated sinusoids. The detection process with OSK i...

The present study focuses on Model Order Reduction (MOR) methods of non-intrusive nature that can be seen as belonging to the category of system identification techniques. Indeed, whereas the system to analyze is considered as a black box, the accurate modeling of the relationship between its input and output is the aim of the proposed techniques....

The jointed structures are widely spread but their behaviour is quite hard to model and to simulate. The talk deals with a decomposition in linear and non-linear substructures that allows to make the simulations easier. The authors show that the modal subspace is not optimal to reduce the order of the model. Another choice of reduction subspace is...

Mechanical joints in assembled structures cause energy dissipation due to micro-slip in contact and softening effects that play an important role in the dynamic behavior of such structures. The contact non-linearity is governed by micro and meso-scale parameters (geometry, roughness, local pressure, etc.) and as a result cannot be included in a mac...

In structural dynamics, the prediction of damping remains the biggest challenge. This paper deals with the energy losses caused by micro-slip in a nominally planar interface of a structure. This paper proposes an analytical and experimental study of flexural vibrations of a clamped-clamped beam with innovative position of the interfaces. The object...

This work proposes a Compact Model Synthesis (CMS) for Partially Observed Operational Systems (POOS) without using the complete knowledge of models. Series of “grey boxes” fed with partial observations are built in order to synthesize target variables with compact models. The recursive process for real time computation is based on Kalman Filters (K...

The talk will deal with measurements of normal loads in assembled structures. A new sensor has been developed to measure the distribution of the normal force in a bolted joint. This sensor is piezoelectric and is associated to an electronic device for carrying out a static measurement. Moreover, the electrode of the sensor is shaped in order to mak...

This paper deals with the damping caused by friction in joints. A new test bench is presented and justified by comparisons made with devices described in the literature. The purpose of this academic bench is to measure the damping induced by partial slip and friction in a planar joint. Moreover, allows uncoupling normal static and dynamic tangentia...

The hereby paper investigates a way to compute the micro-sliding dissipations that occurs in built-up structure using modal coordinates. This numerical method extends the former quasi-static approach to modal displacements through the use of finite element analysis. Considered structures are supposed to behave linearly except for a lumped bolted jo...

This document deals with a method for eigenvalue extraction for the analysis of structures with viscoelastic materials. A generalized Maxwell model is used to model linear viscoelasticity. Such kind of model necessitates a state-space formulation to perform eigenvalue analysis with standard solvers. This formulation is very close to ADF formulation...

The friction between interfaces at bolted joints plays a major role in the damping of structures. This paper deals with the energy losses caused by micro-slips in the joints. The aim of this study is to define in an analytical way these energy dissipation mechanisms which we examine through the analysis of a new benchmark: the flexural vibration of...

This work is a contribution in the field of Operational Modal Analysis to identify the modal parameters of mechanical structures using only measured responses. The study deals with structural responses coupled with harmonic components amplitude and frequency modulated in a short range, a common combination for mechanical systems with engines and ot...

The present paper deals with numerical investigations about the identification of modal damping, due to frictional dissipation, in built-up structures. Such structures are supposed to be fitted with a linear domain and a lumped non-linear bolted joint. Since the non-linearity is lumped the normal eigenmodes of a linearised structure can be used as...

This paper focuses on the generalized Maxwell model (GMM) identification. The formulation of the transfer function of the GMM is defined, as well as its asymptotes. To compare identification methods of the parameters of the GMM, a test transfer function and two quality indicators are defined. Then, three graphical methods are described, the enclosi...

This work is a contribution in the field of Operational Modal Analysis to identify the modal parameters of mechanical structures using only measured responses. The study deals with structural responses coupled with harmonic components amplitude and frequency modulated in a short range, a common combination for mechanical systems with engines and ot...

Generally speaking, the behaviour of viscoelastic material is more complicated than the behaviour proposed by classical models as Voigt, Maxwell or Zener. The stiffness of such materials is a frequency dependent complex function. Above 1000Hz, classical measurements techniques are unable to achieve accurate measurements of the stiffness. In this pa...

In structural dynamics, the problem of damping remains the biggest challenge. This paper deals with the energy losses caused by micro-slip in a planar interface of a structure. Taking into account friction in the joints during the analysis of dynamic systems remains a complex task. This paper proposes an analytical and experimental study of flexura...

This paper presents a numerical modelling of the dynamic behaviour of the Machine-Tool-Part system (MOP) in milling. The numerical study of such complex structure requires the use of sophisticated method like finite elements one. Simulation is employed to predict cutting forces and dynamic response of Machine-Tool-Part system (MOP) during end-milli...

Damping remains the biggest challenge in structural dynamics, especially when it is caused by friction in joints. This work aims at highlighting transient phenomena during partial sliding in joints and quantifying nonlinear dynamic properties in terms of frequency and Loss Factor. To achieve this, a SDOF model based on the modal projection of a con...

This work deals with the investigation and the resolution of chatter vibrations phenomenon in drilling caused by gyroscopic effect. We present a new theoretical study and experimental methodology to investigate the vibration phenomenon appearing in drilling operation. In the first part, we used finites elements of beam design for all the system mac...

This paper focuses on the generalized Maxwell model (GMM) identification. The formulation of the transfer function of the GMM is defined, as well as its asymptotes. To compare identification methods of the parameters of the GMM, a test transfer function and two quality indicators are defined. Then, three graphical methods are described, the enclosi...