WorldCat Identities

Molimard, Jérôme

Works: 26 works in 41 publications in 2 languages and 816 library holdings
Roles: Author, Other, Thesis advisor, Opponent, Contributor
Publication Timeline
Most widely held works by Jérôme Molimard
Experimental mechanics of solids and structures by Jérôme Molimard( )

10 editions published in 2016 in English and held by 715 WorldCat member libraries worldwide

From the characterization of materials to accelerated life testing, experimentation with solids and structures is present in all stages of the design of mechanical devices. Sometimes only an experimental model can bring the necessary elements for understanding, the physics under study just being too complex for an efficient numerical model. This book presents the classical tools in the experimental approach to mechanical engineering, as well as the methods that have revolutionized the field over the past 20 years: photomechanics, signal processing, statistical data analysis, design of experiments, uncertainty analysis, etc. Experimental Mechanics of Solids and Structures also replaces mechanical testing in a larger context: firstly, that of the experimental model, with its own hypotheses; then that of the knowledge acquisition process, which is structured and robust; finally, that of a reliable analysis of the results obtained, in a context where uncertainty could be important
Mécanique expérimentale des solides et des structures by Jérôme Molimard( Book )

5 editions published in 2016 in French and English and held by 73 WorldCat member libraries worldwide

"Depuis la caractérisation des matériaux jusqu'aux tests de durée de vie, l'expérimentation des solides et des structures est présente à toutes les étapes de la conception de dispositifs mécaniques. Parfois, seul un modèle expérimental peut apporter les éléments de compréhension nécessaires, la physique étudiée étant trop complexe pour un modèle numérique efficace. Cet ouvrage présente les outils classiques de l'approche expérimentale en mécanique, mais aussi les méthodes qui révolutionnent le domaine depuis vingt ans : photomécanique, traitement du signal, analyse statistique de données, plan d'expériences, analyse d'incertitudes ... Mécanique expérimentale des solides et des structures replace également l'essai mécanique dans un contexte plus large : tout d'abord, celui du modèle expérimental, avec ses hypothèses propres ; ensuite, celui d'un processus d'acquisition de connaissances, structuré et robuste ; enfin, celui d'une analyse fiable des résultats obtenus, dans un contexte où l'incertitude peut être importante." [Source : 4e de couv.]
Etude expérimentale du régime de lubrification en film mince : application aux fluides de laminage = Experimental study of thin film lubrication. Application to metal rolling fluids by Jérôme Molimard( Book )

2 editions published in 1999 in French and held by 3 WorldCat member libraries worldwide

In the cold rolling process, the strip's quality deeply depends on the contact between the strip, the lubricant and the rolls. This quality -requirement leads to favor the mixed lubrication regime. In this case, important interactions between surface asperities are expected. The lubricant and overall the additives have the important task to protect surfaces. This work suggests studying the lubricant behavior when film thickness is very small in order to bring the additives influence to light. A new film thickness measurement method coupling the classical white light interferometry on a point contact to original image analysis software is designed. First tests on a static smooth contact, then on a rough static on~, and last on a dynamic smooth one show the possibility to obtain a precise film thickness map in a range from 1 to 800 nm. At first, this technique is used with laboratory lubricants in elastohydrodyna.mic lubrication or thin film lubrication. Results are compared to literature, numerical models and another image analysis software. This shows proof of the method's capacity to study thin film regime. In a second time, studies are performed, on two industrial lubricants. The behavior in thin film lubrication is different whether additives are placed or not in the lubricants. If they are some, a low thickness limit appears (2 or 3 nm) and the film thickness can be more important in a low thickness range (typically under 40 nm), preventing surfaces diseases. A model is proposed. It takes into account adsorption and segregation phenomena. Results are consistent to other studies for various lubricants on surface force apparatus or by spectral analysis methods
Développement d'un implant à géométrie variable pour le traitement des fractures du fémur proximal chez les personnes âgées by Rémi Billard( )

1 edition published in 2014 in French and held by 2 WorldCat member libraries worldwide

Proximal femoral fractures in the elderly are generally fixed with osteosynthetic devices. For specific fractures called intertrochanteric, it is possible to fix the fracture in an intramedullary way (inside the bone) or in an extramedullary way (outside the bone). For each type of treatment, hospitals are equipped with the two fixing systems. The differences in physical characteristics between individuals imply the existence of multiple references implants and therefore additional costs in terms of equipment. In this thesis work,an original implant adaptable to most people has been developed. This implant will provide surgeons greater flexibility during surgery but also significantly reduce stocks implants in hospitals. The mechanical behavior of the implant is studied in different cases of fractures by two complementary approaches,a finite element analysis and an experimental study employing stereo-image correlation technique from images of high speed cameras. The results of the numerical calculation are compared with those derived from tests on synthetic femurs, then cadaver in anatomy laboratory. Comparisons with existing implants show that this new implant concept allows for a more stable fixation of bone fragments and a good compression of the fracture
Characterisation of Knee Brace Migration and Associated Skin Deformation During Flexion by Full-Field Measurements by Baptiste Pierrat( )

1 edition published in 2014 in English and held by 2 WorldCat member libraries worldwide

Numerical Approach for the Assessment of Pressure Generated by Elastic Compression Bandage by Fanette Chassagne( )

1 edition published in 2016 in English and held by 2 WorldCat member libraries worldwide

Développement d'un implant d'ostéosynthèse pour le traitement des fractures de l'humérus proximal et diaphysaire moyen : Projet Clothilde by Thibault Goyallon( )

1 edition published in 2019 in French and held by 2 WorldCat member libraries worldwide

The Clothilde Project is a Franco-Swiss partnership between two universities and two companies. This project aims to minimize surgical risks by offering original and reliable devices for orthopaedic shoulder surgery. For this purpose, an osteosynthesis implant to treat proximal and diaphyseal traumatic fractures using metal additive manufacturing is proposed. This device consists of a distal intramedullary locked system combined with a proximal locking system providing great flexibility in bone fragments reconstruction. Specific tools have been developed to confirm the mechanical strength of this medical device. The surgical technique has been validated in anatomy laboratory by a group of surgeons. Five patents have been applied on the chosen solutions (implants and instumentations) which are currently being industrialised
Experimental Investigation of Pressure Applied on the Lower Leg by Elastic Compression Bandage by Fanette Chassagne( )

1 edition published in 2015 in English and held by 2 WorldCat member libraries worldwide

Faciliter l'identification bayesienne des propriétés élastiques par réduction de dimensionnalité et la méthode des surfaces de réponse by Christian Gogu( Book )

2 editions published in 2009 in English and held by 2 WorldCat member libraries worldwide

The Bayesian method is a powerful approach to identification since it allows to account for uncertainties that are present in the problem as well as to estimate the uncertainties in the identified properties. Due to computational cost, previous applications of the Bayesian approach to material properties identification required simplistic uncertainty models and/or made only partial use of the Bayesian capabilities. We propose the use of response surface methodology, dimensionality reduction methods including nondimensionalization, global sensitivity analysis and proper orthogonal decomposition to alleviate computational cost and allow full use of the Bayesian approach. We apply the proposed Bayesian approach to two identification problems of orthotropic elastic constants: first from natural frequencies of a vibrating composite plate, then from full field displacement measurements on a plate with a hole
Characterization of a pressure measuring system for the evaluation of medical devices( )

1 edition published in 2014 in English and held by 1 WorldCat member library worldwide

The purpose of this study is to evaluate the possible use of four "FSA" thin and flexible resistive pressure mapping systems, designed by Vista Medical (Winnipeg, Manitoba, Canada), for the measurement of interface pressure exerted by lumbar belts onto the trunk. These sensors were originally designed for the measurement of low pressure applied by medical devices on the skin. Two types of tests were performed: standard metrology tests such as linearity, hysteresis, repeatability, reproducibility and drift, and specific tests for this application such as curvature, surface condition and mapping system superposition. The linear regression coefficient is between 0.86 and 0.98; hysteresis is between 6.29% and 9.41%. Measurements are repeatable. The location, time and operator, measurement surface condition and mapping system superposition have a statistically significant influence on the results. A stable measure is verified over the period defined in the calibration procedure, but unacceptable drift is observed afterward. The measurement stays suitable on a curved surface for an applied pressure above 50 mmHg. To conclude, the sensor has acceptable linearity, hysteresis and repeatability. Calibration must be adapted to avoid drift. Moreover, when comparing different measurements with this sensor, the location, the time, the operator and the measurement surface condition should not change; the mapping system must not be superimposed
Évaluation de l'effet thérapeutique des ceintures lombaires dans le cadre de la lombalgie chronique by Sara Fortas( )

1 edition published in 2019 in French and held by 1 WorldCat member library worldwide

La lombalgie chronique est une pathologie en recrudescence actuellement en France. Le traitement des lombalgies passe entre autres par le port de ceintures de soutien lombaire. Le mode d'action des ceintures lombaires a très peu été étudié. Il serait intéressant de clarifier leur moyen de fonctionnement afin d'améliorer la prise en charge des patients lombalgiques. Ce travail vise à étudier le mode d'action des ceintures lombaires sur les patients à travers le changement de posture induit et la pression appliquée sur le tronc. Ces données ont été étudiées pour six ceintures lombaires, sur deux types de corpulence différente (un profil de corpulence normale et un profil corpulence en surpoids). L'étude a été réalisée sur des modèles numériques et un modèle expérimental. De ce fait, deux types de troncs ont été utilisés : des troncs numériques et des troncs réels. Dans un premier temps, nous avons constaté que toutes les ceintures lombaires réduisent l'angle de courbure lombaire du rachis et diminuent ainsi l'hyperlordose. Cet effet est différent selon la corpulence du sujet. Dans un second temps, nous avons montré que la pression est appliquée sur le tronc de façon différente selon les ceintures, mais également selon la corpulence des sujets
Comprendre les mécanismes de dissection aortique : modélisation éléments finis et expérimentation in situ sous tomographie RX by Joseph Brunet( )

1 edition published in 2021 in English and held by 1 WorldCat member library worldwide

La dissection aortique est une maladie vasculaire grave caractérisée par un décollement des couches de la paroi artérielle et la création d'un chaux chenal. La mortalité due à cette affection est particulièrement élevée et demande une intervention chirurgicale dans les délais les plus brefs. Bien que largement documentés cliniquement, les phénomènes à l'origine de cette condition sont peu connus et de nombreuses questions demeurent sans réponses. Ainsi, l'objectif de cette thèse est de mieux comprendre les mécanismes déclenchant la dissection aortique et les paramètres influençant sa propagation. Dans un premier temps, deux études combinant des tests mécaniques de traction avec des modèles éléments finis ont permis d'identifier les propriétés mécaniques et les modes de rupture I et II de la paroi aortique grâce à des méthodes inverses. Par la suite, un modèle de dissection aortique utilisant la méthode des éléments finis étendus à été développé afin de quantifier l'impact de facteurs géométriques et mécaniques sur la pression de rupture ainsi que sur la direction de propagation de la dissection aortique. Afin de valider ce modèle, une nouvelle méthode expérimentale combinant un essai mécanique de traction-gonflement avec de la microtomographie à rayons X a été mise au point. Ce test in situ a permis d'observer l'évolution 3D du profil de délamination lors de la propagation d'une dissection dans la paroi. Ces observations et modélisations ont permis une meilleure compréhension des mécanismes de propagation de la dissection, et ouvrent des perspectives sur le développement d'outils de diagnostic personnalisés
Adaptation de la méthode de corrélation d'images numériques pour la gestion des discontinuités du milieu et de la transformation by Hassan Al Husseini( )

1 edition published in 2014 in French and held by 1 WorldCat member library worldwide

The development of the digital image correlation method (DIC) for the management of discontinuities of the material and the transformation is discussed in this thesis. As we know, the framework for the use of the optical measurement methods i.e. of continuum mechanics requires a continuity of: i) domain and ii) transformation. To treat those discontinuities, we can consider a piecewise continuity (material and transformation). In the case of DIC method, this can be done by adapting locally the shape and size of the correlation subsets to the zone of interest and its kinematics. A novel way to do it, is by using masks: an object mask to process material discontinuities and a discontinuity mask to process transformation discontinuities. However before the implementation of masks in the correlation process, several experimental displacement tests on models reproducing the two types of discontinuity at small scale were performed. Those tests proved the influence of discontinuities on the degradation of the measurement accuracy by DIC. Then, tensile tests were conducted on a polycarbonate made specimen knowing a mode I opening or closing crack. After implementing masks in the correlation software Correla, the calculation of displacement and deformation fields was successfully performed on the surface of this specimen for all its edges, demonstrating the effectiveness of the adapted DIC
Développement des techniques optiques et acoustiques de mesure de champs orientées vers la vibroacoustique by Ioana Theodora Nistea( )

1 edition published in 2010 in French and held by 1 WorldCat member library worldwide

The use of optical measurement techniques requires a choice, often difficult, between temporal resolution and spatial resolution. Speckle interferometry (IS) provides high spatial resolution maps of vibration amplitudes, but the temporal resolution of measurements is reduced, due to the low acquisition rates of detectors. The thesis is dedicated to the development of an interferometric system that is able to measure dynamic phenomena with superior temporal resolution. The system was tested at acquisition rates exceeding 26,000 frames/s, for the following cases: harmonic excitation; arbitrary excitation; dynamic loading by a staircase signal and mechanical shock. The tests showed that the system is able to overcome conventional systems of continuous wave SI with respect to the measurement of dynamic phenomena
Suivi par methode optique du frittage micro-ondes d'oxydes ceramiques. by Daniel Zymelka( )

1 edition published in 2012 in French and held by 1 WorldCat member library worldwide

Microwave sintering is known to be a promising sintering technology. Indeed, this method has advantages such as reducing the duration of heat treatment and a significant energy saving compared with conventional processes. Year after year, sintering in a microwave environment is studied by a growing number of researchers. However, the reasons for the beneficial effect of this type of sintering are not clearly identified.In this context, the objective of this work was to verify the influence of an electromagnetic field at a frequency of 2.45 GHz on the densification of ceramic materials. This objective therefore involves a comparative study of sintering in a microwave chamber and in a conventional oven. However, the presence of electromagnetic field in a microwave oven does not allow the use of conventional methods to monitor the sintering. Thus, to compare the results, an experimental system containing a high resolution contactless dilatometer has been specifically developed. This system also allows monitoring of the temperature distribution on the sample surface.For identical thermal cycles, obtained by conventional and microwave sintering, the densification evolution of materials with different properties was compared. These materials are: pure alumina and doped with 800ppm magnesium oxide, zinc oxide and silicon-substituted hydroxyapatite. For each material, the coupling with the microwaves and the temperature distribution on the surface sample are also discussed. A beneficial effect of microwaves on the evolution of densification has been identified for alumina with addition of MgO and more pronounced for zinc oxide
Caractérisation de l'effet de la microstructure collagénique sur le comportement mécanique global des peaux reconstruites by Simon Tupin( Book )

in French and held by 1 WorldCat member library worldwide

The aim of this thesis is the multi-scale study of the mechanical and structural properties of artificial skin. Firstly, an experimental device was designed to evaluate the mechanical properties at macroscopic scale (indentation and relaxation tests). Bi-axial study of the stiffness of different layers through depth was performed with an original device based on continuous stiffness measurements. Combination of bi-photonic confocal microscopy with a tensile test permitted the assessment of the Poisson coefficient of the reconstructed tissues, stresses and tensile forces of the collagen fibers network. Results of the studies revealed the suitability of the developped experimental tools to study aging mechanism and microstructure effects on the global mechanical behavior of artificial skin
Analyse expérimentale de la propagation de fissures dans des tôles minces en al-li par méthodes de champs by Rébécca Berge-Gras( )

1 edition published in 2011 in French and held by 1 WorldCat member library worldwide

This work concerns tensile tests carried out on notched Aluminum-Lithium specimens, with in-situ observations of the strain field.Reducing aviation fuel consumption is currently a priority. Al-Li alloys are excellent candidates for reducing weight of aircrafts. They combine very good mechanical properties with a lower density than conventional alloys. However, the mechanical properties of these materials are highly anisotropic, and it is essential to control this phenomenon in order to use the material wisely. To that end, it is necessary to have an enormous amount of information on the material both microstructural (size and shape of grains ...) and mechanical (yield strength, Young modulus, resistance to cracking ...) properties. But the knowledge of these overall mechanical properties is not enough to maximize resistance to cracking (critical in aeronautic application). In this context, this work aims to quantify the influence of local microstructure (orientation and size of grains) on cracking.Crack propagation in 2 mm thick Al-Li sheet metal has been analyzed. Tension test were carried out on deeply notched specimens with optical in-situ observation of the displacement field.Thus, grid method was adapted to determine large strains in the grains. The displacement field was characterized through the deformation of a bonded crossed square grid (path 30 µm), and the parameters affecting the quality of results (resolution and spatial resolution) have been optimized. In order to compensate the rigid body motion, a new automatic image acquisition system leading to small strains between each image have been developed. A new phase extraction method has been introduced allowing a temporal phase unwrapping
Elastographie ultrasonore des tissus mous du membre inférieur en vue de la caractérisation des effets mécaniques de dispositifs médicaux textiles by Fanny Frauziols( )

1 edition published in 2015 in French and held by 1 WorldCat member library worldwide

La compression élastique de la jambe est le traitement de référence des pathologies liées à l'insuffisance veineuse. Bien que l'efficacité ne soit plus à prouver, les objectifs thérapeutiques restent non atteints pour certains patients. Un objectif de la compression élastique est la réduction de la pression pariétale des veines afin de rétablir ou d'augmenter le retour du sang vers le cœur par une transmission de pression au travers des tissus mous. Ce mécanisme est complexe et peut être prédit par des modèles éléments finis personnalisés. Pour être personnalisés, ces modèles doivent prendre en compte la géométrie et la carte des propriétés mécaniques du sujet.Dans cette étude, on développe deux méthodologies permettant d'identifier les propriétés mécaniques des tissus mous. Dans un premier temps, on mesure par élastographie ultrasonore par onde de cisaillement la distribution du module élastique au sein des tissus mous superficiels. Dans un deuxième temps, on identifie par une méthode inverse les propriétés mécaniques des tissus mous profonds. Cette méthode associe l'acquisition de données d'un essai expérimental de compression localisée de la jambe à un modèle éléments finis bidimensionnel. Ces deux méthodologies nous permettent d'évaluer l'hétérogénéité des propriétés mécaniques de la peau au fascia cruris et de caractériser le comportement non-linéaire des tissus mous profonds. Enfin, les résultats de ces deux méthodologies sont couplés afin de générer un modèle biomécanique de la jambe sous compression élastique pour prédire la distribution de pression au sein des tissus mous pour quatre sujets sains
Étude numérique et expérimentale de procédé d'élaboration des matériaux composites par infusion de résine by Peng Wang( )

1 edition published in 2010 in French and held by 1 WorldCat member library worldwide

Weight saving is still a key issue for aerospace industry. For instance 50% in weightof the B787 and A350 aircraft structures is made of CFRP, so it is necessary to makelighter thick and complex parts. Direct processes called Liquid Composite Molding(LCM), such as Resin Transfer Moulding (RTM) or Resin Infusion Process (LRI, RFI).At the present time, around 5 to 10% of the parts are manufactured by direct processesand the current trend is clearly to go ahead. In RTM process, the dimensional tolerancesand porosity fraction can be kept under control and high quality parts produced, but itsindustrialisation is complex and refined models are still needed to perform simulations.On the contrary, the resin infusion process can be utilized in flexible conditions, such asin low cost open moulds with vacuum bags in nylon or silicone. This type of processonly requires low resin pressure and the tooling is less expensive than RTM rigidmoulds. Therefore LRI and RFI processes are particularity suitable for small andmedium size companies because the investments are rather low compared to othermanufacturing process.Liquid Resin Infusion (LRI) processes are promising manufacturing routes toproduce large, thick or complex structural parts. They are based on the resin flowinduced across its thickness by pressure applied onto a preform / resin stacking.However, both thickness and fibre volume fraction of the final piece are not wellcontrolled since they result from complex mechanisms which drive the transientmechanical equilibria leading to the final geometrical configuration. In order tooptimize both design and manufacturing parameters, but also to monitor the LRIprocess, an isothermal numerical model has been developed by P. Celle [1], whichdescribes the mechanical interaction between the deformations of the porous mediumand the resin flow during infusion. With this numerical model, we have investigated theLRI process with classical industrial piece shapes. To validate the numerical model andto improve the knowledge of the LRI process, the researcher work details a comparisonbetween numerical simulations and an experimental study of a plate infusion testcarried out by LRI process under industrial conditions. From the numerical prediction,the filling time, the resin mass and the thickness of the preform can be determined. Onanother hand, the resin flow and the preform response can be monitored bymicro-thermocouples, optical fibre sensor and fringe projection during the filling stage.One key issue of this research work is to highlight the major process parameterschanges during the resin infusion stage, such as the preform and resin temperature, thevariations of both thickness and fiber volume fraction of the preform. Moreover, thesetwo approaches are both good ways to explore and improve our knowledge on the resininfusion processes, and finally, to develop simulation tools for the design of advancedcomposite parts
Etude de la réactivité et de la stabilité thermique des apatites phosphocalciques carbonatées pour un frittage contrôlé d'implants personnalisés by Sophie Guillou( )

1 edition published in 2020 in French and held by 1 WorldCat member library worldwide

The incorporation of carbonate ions within the apatite structure is a relevant solution for improving hydroxyapatite (HA) bioactivity and tailoring its biodegradation kinetics. Processing of carbonated hydroxyapatite (CHA) bioceramics requires heat-treatments, which induce solid-gas reactions with the atmosphere, necessarily CO2-rich. These ionic exchanges dictate the purity, the chemical composition and the microstructure of the final piece. For the first time, these ionic exchanges have been studied. An original characterization protocol of HA composition was developed to this end. Oxygen atoms on A-sites were identified as preferential reactive sites. The exchanges kinetic law appeared to depend on the sinterability of the powder: a specific surface area reduction acts as a driving force for the exchanges. To supplement these results, the solid-gas reactions were modelled using a thermodynamic approach. The models can be used to predict the decomposition temperature of a compound and its composition after a heat-treatment under a controlled atmosphere. This expertise of the ionic exchanges permitted to study their impact on matter diffusion. Exchanges with a dry CO2 rich-atmosphere delay densification at higher temperatures but accelerate sintering from 1050 °C. Adding water vapour modifies these ionic exchanges in a still poorly understood way, and leads to fine and homogeneous microstructures. This study provides a solid framework to design customized bone substitutes in CHA with controlled composition and microstructure
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Audience level: 0.34 (from 0.27 for Experiment ... to 0.97 for Experiment ...)

Experimental mechanics of solids and structures
Alternative Names
Jérôme Molimard researcher

Jérôme Molimard wetenschapper

English (18)

French (17)