Emile Roux

Université Savoie Mont Blanc | UdS · SYMME Systems Laboratory Mechatronics and Materials

In this article, we propose the modelling of a tunable Bistable Piezoelectric Energy Harvester (or BPEH) architecture. The former is a type of ambient energy converters that continue to gain attention due to their wideband frequency response. As the non-linear dynamics of BPEHs imply significant modeling complexity, dynamic lumped models are necess...

In the field of medical applications, precise localization of medical instruments and bone structures is crucial to ensure computer-assisted surgical interventions. In orthopedic surgery, existing devices typically rely on stereoscopic vision. Their purpose is to aid the surgeon in screw fixation of prostheses or bone removal. This article addresse...

This paper introduces an optimized orbit jump strategy for nonlinear vibration energy harvesters (VEHs). Nonlinear VEHs are a promising alternative to linear VEHs due to their broadband characteristics. However, they exhibit complex dynamical behaviors, including not only high-power inter-well orbits but also low-power intra-well orbits and chaos....

Nonlinear Vibration Energy Harvesters (VEHs) are widely used for scavenging vibrational energy due to their broadband behaviors. However, they exhibit multiple orbits of different powers for a given excitation, including low-power orbits that might limit their performance. To address this issue and enhance nonlinear VEHs performance, various studie...

Material heterogeneity has a considerable effect on spring back. Integrating heterogeneity in a simulation to obtain a more accurate spring back prediction is complex and often requires a significant number of tests and parameters. Whilst in the industry, the necessity of predicting forming process outcomes, e.g. the spring back of the material, is...

This paper introduces an optimized orbit jump strategy for nonlinear Vibration Energy Harvesters (VEHs). Nonlinear VEHs are a promising alternative to linear VEHs due to their broadband characteristics. However, they exhibit complex dynamical behaviors, including not only high-power inter-well orbits but also low-power intra-well orbits and chaos....

Nowadays these structures are at the end of their theoretical life according to Eurocode 2. It is entitled to ask questions about their state of health, and whether these structures are still able to ensure their activity in respect of constantly evolving regulations, while ensuring public safety. To tender to answer these questions, we have develo...

Vibration energy harvesters (VEHs) allow the extraction of ambient mechanical energy. The proposed analysis focuses on bistable harvesters with Duffing nonlinearity. Bistable harvesters exhibit larger frequency bandwidth than linear monostable harvesters, but they exhibit complex behaviors (i.e., multiple periodic orbits and chaos), making their ev...

This paper reports the design and fabrication of an innovative small-size propeller and its experimental testing once assembled with an electromagnetic generator. The bioinspired rotor is based on the shape and behaviour of maple samaras that optimise the aerodynamics at low Reynolds numbers. To the authors' knowledge, it is the first samara-based...

In order to scavenge the energy of ambient vibrations, bistable vibration energy harvesters constitute a promising solution due to their large frequency bandwidth. Because of their complex dynamics, simple models that easily explain and predict the behavior of such harvesters are missing from the literature. To tackle this issue, this paper derives...

Flax-fibre composites are increasingly used as a replacement of classical synthetic composite materials. Due to the good energy absorption properties of flax fibres, they represent a promising alternative in structures susceptible to low velocity impact (LVI) damage. However, this type of dynamic loading is complex, expensive to perform and not nec...

The mechanical response of magnesium alloy AZ31B is addressed thanks to four-point bending tests. These alloys are known to have an asymmetrical behavior in tension-compression. The bending test is, therefore, a good candidate to analyze this effect because it combines the two solicitations. Digital image correlation is used to measure the evolutio...

Material parameters identification by inverse analysis using finite element computations leads to the resolution of complex and time-consuming optimization problems. One way to deal with these complex problems is to use meta-models to limit the number of objective function computations. In this paper, the Efficient Global Optimization (EGO) algorit...

Highlights Compartmentalized models are able to reproduce loading–unloading–reloading (LUR) cycles on DP steels. The evolution of the apparent moduli measured on the unloading and reloading steps is well reproduced by the model while using a constant intrinsic Young's modulus using only 5 parameters. This evolution predicted spontaneously when the...

__________________________________________________ This paper focuses on the importance of taking into account the acceptable whitening limit of the protective coating of metals after forming processes. Coating aspects are essential to validate final products, especially if the coating has a design feature. The material studied is a standard zinc a...

The accurate springback prediction of dual phase (DP) steels has been reported as a major challenge. It was demonstrated that this was due to the lack of understanding of their nonlinear unloading behavior and especially the dependency of their unloading moduli on the plastic prestrain. A so-called compartmentalized finite element model was develop...

This work is based on the study of the behaviour of flax fibres twill reinforced epoxy composites. The aim of the study is to determine the modulus of elasticity, Poisson coefficients and strength of these composites materials with image correlation. The specimens used in this work were manufactured by the infusion vacuum process and after subjecte...

This work aims at studying the low velocity impact and post-impact behaviour of flax/epoxy composites. The samples were composed of 8 plies of 2/2 twill weave fabric. The experimental device used for impact tests was a drop tower with impact energies varying from 5 to 34 J (perforation). Pictures of the sample were captured during the test with two...

Les matériaux étudiés dans cet article sont des composites constitués d'une résine époxyde et de renforts tissés de type sergé 2/2 en fibres de lin. Les composites stratifiés sont composés de 4, 6 et 8 plis. Les échantillons ont été réalisés par le procédé de moulage par injection sous vide. L'étude vise à déterminer l'évolution du comportement de...

Many studies show the efficiency of large-scale wind turbines in wind energy harvesting for collective applications. However, few examples relate to small one stage wind turbines (OSWT) for mobile and individual applications. This work details the modeling and the prototype realization of a 18 cm diameter wind turbine using counter-rotating propell...

Many studies show the efficiency of large-scale wind turbines in wind energy harvesting for collective applications. However, few examples relate to small one stage wind turbines (OSWT) for mobile and individual applications. This work details the modeling and the prototype realization of a 18 cm diameter wind turbine using counter-rotating propell...

Apport des mesures de champ dans l'étude de composites renforcés en fibres de lin au cours d'essais de traction quasi-statiques Contribution of field measurements in the study of composites reinforced with flax fibers during quasi-static tensile tests Résumé Ce travail porte sur l'étude du comportement de matériaux composites constitués d'une résin...

Impact tests on pre-notched plates are carried out to analyze qualitatively and quantitatively the crack development in high strength steel under high loading rate. Implementation of ultra-high speed camera (1M frame/s) allows on one hand observing the chronology of the failure mechanisms from adiabatic-shear-banding until full fracture. On the oth...

This paper is focused on the identification method by inverse analysis of ductile damage model parameters. The Lemaitre damage model is considered. The aim is to assess the interest of using local measurements, such as full field measurements, in the calibration process. Basic approach using only load-displacement measurements from a tensile test i...

In the present work, the engineering, high strength ARMOX500T steel was submitted to a Kalthoff and Winkler type impact test in view of evaluating its crack arrest capability under dynamic loading. From an impact velocity of the order of 150 m/s, the crack propagation is seen to be preceded by adiabatic shear banding (ASB) leading to a premature pl...

http://cfrac2015.sciencesconf.org/55039

Une méthode d’analyse numérique d’images est proposée permettant de suivre le déplacement de points localisés le long de lignes gravées sur une plaque. Cette technique permet d’une part d’identifier les champs cinématiques successifs conduisant à la ruine dynamique de la structure et d’autre part de quantifier les vitesses de propagation mises en j...

Experimental analysis of fracture mechanisms is a key point to understand and further reproduce physical phenomena involved in structural material failure. Actually, crack propagation under high loading rate is a strongly coupled thermo-mechanical problem involving large deformation, high strain rate and (quasi) adiabatic conditions. The work prese...

A two-dimensional finite element (FE) model is presented to model the nucleation and void growth stages in ductile damage phenomena on the microstructure scale. This model is based on a level-set (LS) method coupled with an advanced re-meshing strategy. Both nucleation modes (interface debonding and inclusion fracture) are modelled through the intr...

The plastic behavior of a ferritic stainless steel under non-proportional loading was investigated using a biaxial test setup developed at the University of Twente. With this testing device, a specimen can be subjected to both plane strain tension and simple shear stress states in an arbitrary order. A number of tests are conducted including differ...

A robust production is an important goal in sheet metal forming in order to make the process outcome insensitive to variations in input and process conditions. This would guarantee a minimum number of defects and reduced press downtime. However, for com-plex parts it is difficult to achieve robust settings. Parts without defects can only be real-iz...

The hot rollability of two V-steels: Free Cutting FC-9SMn28 and Medium-Carbon MC-38MnSiV5 has been investigated. Defect samples have been taken from industrial campaign and pilot mill rolling experiments and microstructures characterised. Mechanical testing has been performed to obtain constitutive and damage equations for defect-free sound materia...

Clinching is a very cheap and efficient cold forming process that enables to join two sheets without any additional part such as a rivet or a bolt. This paper deals with the optimization of the final mechanical strength of a joined component using a global optimization technique based on Kriging meta-model. The optimization process includes both th...

Ductile damage prediction is still an important issue in the mechanical industry. Ductile failure criteria as well as coupled damage models were enhanced in the last decade by accounting for the influence of stress triaxiality ratio and Lode angle. For the Gurson-Tvergaard-Needleman (GTN) model, these improvements were essentially made for the grow...

Au cours des dix dernières années, une attention particulière a été portée à la modélisation de l'endommagement ductile et à l'enrichissement des modèles macroscopiques pour des trajets de chargement complexes. Cependant, les mécanismes d'endommagement ductile sont fortement liés à la microstructure des matériaux étudiés. Nous nous intéressons ici...

A numerical model based on the use of a level set framework coupled with an anisotropic re-meshing technique is presented in order to describe the void growth process for 2D and 3D configurations. Interfaces of inclusions and voids are described implicitly using level set functions. An anisotropic meshing – remeshing strategy is employed to track i...

In the last ten years, there is a impressive development of numerical simulation codes for metal forming processes, and their use in industry for realistic process analysis and design is more and more intensive. To-day new needs have emerged, in particular "automatic" optimization of processes, using more and more complicated criterions, in order t...

The fundamental mechanical assumptions and the basic principles of 3-dimensional FE discretization are briefly summarized. Several important numerical developments for efficient and accurate computation of large plastic deformation are discussed. Material behavior must be known precisely: material parameters of the constitutive law, thermal law and...

This study deals with the development of a numerical strategy dedicated to mechanical joining processes optimisation and to parameters identification by inverse analysis. The first part is dedicated to the definition and development of an optimisation and inverse analysis platform. This platform is adapted to finite element computations. An optimis...

A micro-scale finite element model is presented in order to describe ductile fracture phenomena for steel alloys. Ductile damage usually involves the nucleation, growth and coalescence of microvoids in a plastically deforming material. This study focuses on the voids growth process. It is assumed that voids already exist, either due to matrix/inclu...

Automatic remeshing has been used for many years within the framework of materials forming processes to preserve the good quality of elements even for large plastic deformation. Automatic mesh adaptation, coupled with an appropriate error estimator, enables to optimize automatically the mesh size during the simulation to obtain accurate results in...

Identification of material parameters is an important issue to improve the accuracy of finite element computations. Identification of these parameters by inverse analysis is based on experimental observables coming from mechanical experiments. In this paper, a simple tensile test is used. Two types of observables are investigated to identify ductil...

Ductile damage mechanics is essential to predict failure during cold metal forming applications. Several damage models can be found in the literature. These damage models are coupled with the mechanical behavior so as to model the progressive softening of the material due to damage growth. However, the identification of damage parameters remains an...

The fundamental mechanical assumptions and the basic principles of 3-dimensional FE discretization are briefly summarized. Several important numerical developments for efficient and accurate computation of large plastic deformation are discussed. Material behavior must be known precisely: material parameters of the constitutive law, thermal law and...

Calibration of damage parameters is an important issue for the use of damage laws, and particularly for industrial manufacturing processes. This paper deals with an adapted procedure to identify Lemaitre damage parameters using tensile tests. An adapted objective function is built, and Efficient Global Optimisation (EGO) algorithm is chosen to solv...