Jean-Luc Dion

• PhD
• Professor (Full) at Institut Supérieur de Mécanique de Paris

This article explores the hysteretic behavior and the damping features of sheared granular media using discrete element method (DEM) simulations. We consider polydisperse non-cohesive frictional spherical particles, enclosed in a container with rigid but moving walls, submitted to a cyclic simple shear superimposed to a confining pressure. The mech...

We explore a passive control solution of bending waves in beams, which takes advantage of the dissipative properties of granular media. It consists in a layer of particles confined between two beams and interacting with each other through their contacts. The inter-particles contacts are intrinsically dissipative due to friction, which efficiently w...

We propose a method to measure the vibrations amplitude of normal modes of a 3D mechanical structure with only one camera. Our method requires only a video sequence taken by a single camera and a collection of admissible 3D deflection shapes. The deflection shapes are projected in the image frame of the camera. This is done thanks to a linearizatio...

Smart factories are composed of heterogeneous cyber-physical systems. In light of their complexity and the lack of transparency in their design, monitoring the health of these machines in real time is made possible by the use of nonintrusive sensors. Such sensors produce mixed signals capturing component-specific signatures. Retrieving the activati...

To design a vehicle suspension the knowledge of wheel loads is required. These loads are due to road unevenness and can be identified thanks the acquisition of measurements during vehicle rolling on roads or tracks. Some offline methods are used to identify them; most of these methods are based on transfer functions between points of measurements a...

This study proposes to carry out the experimental modal analysis of nonlinear systems under the assumption of almost invariant modal shapes by coupling video analysis from a high speed/resolution camera and extended Kalman filtering. A clamped-clamped beam with a local nonlinearity is considered, and its vibrations are measured by detecting and tra...

L’invention propose un kit d’amortissement vibratoire (40) pour un équipement (12) fixé à une structure (22) susceptible d’être soumise à des vibrations, ledit équipement (12) étant fixé à ladite structure (22) par l’intermédiaire d’un support (24) comportant au moins une cavité (30), Caractérisé en ce qu’il comporte : un milieu granulaire (46) non...

Marble is a fragile and heterogeneous material whose properties vary depending on the nature and origin of the marble. Therefore, the marble machining process requires the skills and know-how of the stone cutter to manually configure the machining parameters for each piece of marble. This study addresses the enhancement of quality achieved by marbl...

With the ever increasing complexity of Industry 4.0 systems, plant energy management systems developed to improve energy sustainability become equally complex. Based on a Model-Based Systems Engineering analysis, this paper aims to provide a general approach to perform holistic development of an autonomous energy management system for manufacturing...

The design of a vehicle suspension requires the knowledge of wheel loads due to road unevenness. These loads can be identified from measurements acquired during vehicle rolling on roads or tracks. Different off-line methods are used to identify them. Most of these methods use some transfer functions between points of measurements and hypothesis of...

This paper investigates the rocking behavior of rigid bodies seismically protected by means of lead rubber bearings and high damping rubber bearings, which are the most popular kinds of elastomeric isolators in the market. The complex nonlinear force–displacement relationship displayed by such devices is predicted by a phenomenological model based...

With the ever increasing complexity of Industry 4.0 systems, plant energy management systems developed to improve energy sustainability become equally complex. Based on a Model-Based Systems Engineering analysis, this paper aims to provide a general approach to perform holistic development of an autonomous energy management system for manufacturing...

Madame, Monsieur, cher(e) collègue, Dans tous les secteurs industriels, les exigences de performance et de fiabilité, imposées aux composants et structures d’aujourd’hui, requièrent des solutions d’assemblages innovantes et adaptées. C’est pourquoi, comme suite au succès des trois premiers, ce 4ème colloque se propose de faire un point sur les as...

Ground vehicle architectures are designed to prevent the transmission of vibration, shock, and noise from the ground profile under operating conditions. The choice of a kinematic architecture strongly contributes to the filtering efficiency of the complete system and has to be considered before the efficiency of the suspension components. In order...

In this paper, we propose a new method to measure the vibrations of a 3D mechanical structure. It requires only a video sequence taken by a single camera and a Finite Element model of the structure. First, the intrinsic and extrinsic parameters of the camera are identified. Then, a collection of numerical deflection shapes and normal modes are proj...

This paper describes an experimental and theoretical approach to evaluate cycloid drive reducer efficiency. The tests are carried out on 7.5 kW two-disc cycloid drive with a gear ratio of 19. The torque and speed are measured on the input and output shaft. The efficiency is calculated based on the obtained results. The main goal of the second part...

In many engineering applications, the vibration analysis of a structure requires the set up of a large number of sensors. These studies are mostly performed in post processing and based on linear modal analysis. However, many studied devices highlight that modal parameters depend on the vibration level non linearities and are performed with sensors...

With the increasing number of rotors working at very high angular velocity, it becomes crucial to understand the dynamic behavior of rotating machineries when going through critical speeds. Models assuming constant velocity speed are not valid in this case of study since crossing the critical speeds implies necessarily non-stationary working condit...

The aim of this work is to provide a new model describing the dynamic behavior of the rotating machinery working under non-stationary conditions with no assumption on the IAS. This new model will provide an identification tool for the rotor parameters. An example of a simple rotor made of a flexible shaft, a rigid disk, bearings and a mass unbalanc...

Complexity of dynamical systems are increasing more and more as well as their mathematical models. At the same time, simulation of system behaviour assumes a key role to assure the fulfillment of requirements as performances, quality, safety, and robustness. Therefore, due to model complexity, it is often very complex to assess a system behaviour b...

In the automotive industry, high-speed elecrical engines will be used in a very large range of speeds, leading to non-stationary operating conditions. Thus more critical speeds may be crossed a very large number of times during the whole life-time of the engine. Therefore, estimating accurately the non-stationary loads and deformations during these...

In order to perform faster simulations, the model reduction is nowadays used in industrial contexts to solve large and complex problems. However, the efficiency of such an approach is sometimes cut by the interface size of the reduced model and its reusability. In this article, we focus on the development of a reduction methodology for the build of...

Speed reducers with input shafts spinning at very high speeds (up to 42 000 rpm) are generally associated to electric motors, which are more and more used especially in the automotive field, in order to bring the rotational speed to the most efficient window. Accurate modeling of those rotating machinary behavior is crucial to improve product relia...

The growing use of rotating machines operating in non-stationary conditions gave rise to a greater need to a higher precision for describing their dynamic behavior. The latter has always been based on a certain number of simplifying assumptions. In particular, the spinning speed is considered either constant or following a given law of variation as...

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...

It is well known that the friction between interfaces at bolted joints plays a major role in the characterization of damping. Friction can be either induced by macroslip or microslip. The aim of this chapter is to model and quantify the dissipated energy by microslip in the joints in order to compute the damping ratio. It is assumed that the coeffi...

The aim of this paper is to describe the development of a reduced order model for modal analysis in a design context. The design process of most industrial systems is based on the re-utilization of certain components. Here, we propose a reduction method involving component eigenmodes to recover the modal behaviour of an assembled structure. The con...

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...

This paper focuses on energy losses caused by inner damping and friction in an elastomeric rotational joint. A description of the design of a new experimental device intended to characterize dynamic stiffness in rotational elastomeric joint is presented. An original method based on Lagrange’s equations, which allows accurately measuring forces and...

The use of high speed cameras for dynamics is not a recent idea. Moreover, visual information is everyday more present, cameras are more and more fast, small and accurate. Improvements in computer vision enable to go further: to consider cameras as smart sensors. In this framework, this article propose to merge a non-linear model of structural dyna...

Nowadays, visual information is everyday more present, cameras are more and more fast, small and accurate. Improvements in computer vision enable to go further: to consider cameras as smart sensors. In this framework, this article propose to mix complex mechanical models with video processing in order to estimate invisible parameter and to enable t...

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 dynamic characteristics of viscoelastic components depend on frequency, amplitude, preload, and temperature. A Non Linear Generalized Maxwell Model (NLGMM), with only 4 independent parameters is proposed. The proposed NLGMM is based on the decomposition between the linear viscoelasticity and the non linear stiffness. This assumption is validate...

The speed wobble is a phenomenon in nonlinear dynamics that can occur in many vehicles such as bicycles, motorbikes, skateboards and airplanes nose landing gear. The dynamic instability affects the steerable wheels of a vehicle and can lead to the loss of control. While for bikes, motorbikes and airplanes the dynamics and causes of the wobble are w...

In order to perform faster simulations, the model reduction is nowadays used in industrial contexts to solve large and complex problems. However, the efficiency of such an approach is sometimes cut by the interface size of the reduced model and its reusability. In this article, we focus on the development of a reduction methodology for the build of...

In computer vision, cameras more and more accurate, fast, 3D featured are used. These still evolutions generate more data, which is an issue for users to store it with standard compression for example for recording proof in case of products manufacture defective. The aim of this work is to develop a specific solution adapted for vision systems whic...

This paper describes a method for the identification and the tracking of poles of a weakly nonlinear structure from its free responses. This method is based on a model of multichannel damped sines whose parameters evolve over time. Their variations are approximated in discrete time by a nonlinear state space model. States are estimated by an iterat...

The most common method of vibration control is the use of the dynamic absorbers. Two types of absorbers can be found: Linear and nonlinear. The use of linear absorbers allows reducing vibration but only at the resonance frequency, whereas nonlinear absorbers attenuate vibration on a wide band of frequency. In this paper, a nonlinear two degrees of...

It is well known that bolted joints have significant influence on the dynamical behavior of assembled structures due to formation of damping. This paper focuses on damping caused by dry friction in a rotational joint. Friction can be either induced by micro-slipping or macro-slipping. This paper describes the design of a new experimental device int...

Vibrations are usually undesired phenomena as they may cause discomfort, disturbance, damage, and sometimes destruction of machines and structures. It must be reduced or controlled or eliminated. One of the most common methods of vibration control is the use of the dynamic absorber. The paper is interested in the study of a nonlinear two degrees of...

Characterizing frictional behavior of viscoelastic joints is investigated in the present work. A new visco-tribological model was developed by coupling the rheological Generalized Maxwell model (GMM) and Dahl friction model. Parameters of the proposed model are identified from Dynamic Mechanical Analysis (DMA) tests for different excitation frequen...

The most common method of vibration control is the use of the dynamic absorbers. Two types of absorbers can be found: Linear and nonlinear. The use of linear absorbers allows reducing vibration but only at the resonance frequency, whereas nonlinear absorbers attenuate vibration on a wide band of frequency. In this paper, a nonlinear two degrees of...

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...

The aim of this paper is to investigate non linear dynamic behavior of viscoelastic components. The dynamic characteristics of viscoelastic components depend on frequency, amplitude, preload, and temperature. A Non Linear Generalized Maxwell Model (NLGMM), with only 4 independent parameters, is proposed. The NLGMM is based on the separation between...

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...

Viscoelastic joints connecting solids are essential components of mechanical systems. Viscoelastic components have inherent damping in their structure. Moreover, energy losses in structural vibrations are strongly linked to the friction properties of joints. In this work, a new visco-tribological model was developed by coupling the rheological line...

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...

It is well known that the friction between interfaces at bolted joints plays a major role in the damping of assembly structures. Friction can be either induced by macro-slipping or micro-slipping. The aim of this paper is to model and quantify the dissipated energy by micro-sliding down to the scale of roughness between two flat surfaces in order t...

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...

Characterizing frictional behaviour of viscoelastic joints is investigated in the present work. A new visco-tribological model was developed by coupling the rheological Generalized Maxwell model and Dahl friction model. Parameters of the proposed model are identified from Dynamic Mechanical Analysis (DMA) tests for different excitation frequencies....

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...

Viscoelastic components are incorporated into automobile and aerospace structures system in order to damp mechanical vibrations. Viscoelastic components are a key element in designing desired dynamic behaviour of mechanical systems. Viscoelastic components dynamic characteristics are often very complex, due to the dependence of its response on seve...

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...

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 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 paper develops an experimental and numerical study of dynamic phenomena involving gear impacts with one loose gear (non-engaged gear pair) inside an automotive gearbox.A dedicated test bench was designed for this study. Signal processing tools, based on the Order Tracking Method, were specially developed in order to clarify the underlying phen...

Dynamic computation of braking systems including viscoelastic behaviours. In the context of brake system simulation, the highlight of phenomenon like squeal needs specific methods. We will focus on stability analysis by complex modal analysis. The use of damping system called shims for squeal noise reduction implies that simulations take into accou...

The nonlinear dynamic behaviour of preloaded traditional multilayer plates incorporating visco-hyperelastic materials is investigated. The visco-hyperelastic material was confined between stiff layers and worked as a damping layer. The full structure is submitted to shear vibrations under a compression preload. We present herein a nonlinear model d...

After a description of existing experimental methods and models built on the dynamic behavior of friction forces between two solids, this paper presents an original new test bench and specific measurement techniques used to better define the accuracy of measurements. This test bench has been designed for a large range of tests in terms of static st...

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 difficult. This paper proposes an analytical study of flexural vibrations of a clamped-clamped beam, the novelty of this experiment is that the position of the i...