Papers by Virginie Taillebot
International Journal of Fracture, Dec 15, 2010
Shape Memory Alloys (SMAs) such as NiTi exhibit stress induced martensitic phase transformation. ... more Shape Memory Alloys (SMAs) such as NiTi exhibit stress induced martensitic phase transformation. The purpose of this paper is to provide a better understanding of SMA (such as NiTi) fracture behavior, by considering the vicinity of the crack tip where the transformation occurs. This analysis integrates the asymmetry between tension and compression in an analytical prediction of the surface of phase transformation around the crack tip for loading modes 1, 2, 3 and mixed 1+2. The influence of the asymmetry between tension-compression is more important in plane stress conditions than in plane strain conditions, particularly for mode 1 loading. In order to validate this model, we are currently setting up an experimental investigation to observe strain localization during crack propagation (transformation and martensitic saturation regions) on NiTi thin sheets.
International Journal of Fracture, 2010
Shape Memory Alloys (SMAs) such as NiTi exhibit stress induced martensitic phase transformation. ... more Shape Memory Alloys (SMAs) such as NiTi exhibit stress induced martensitic phase transformation. The purpose of this paper is to provide a better understanding of SMA (such as NiTi) fracture behavior, by considering the vicinity of the crack tip where the transformation occurs. This analysis integrates the asymmetry between tension and compression in an analytical prediction of the surface of phase transformation around the crack tip for loading modes 1, 2, 3 and mixed 1+2. The influence of the asymmetry between tension-compression is more important in plane stress conditions than in plane strain conditions, particularly for mode 1 loading. In order to validate this model, we are currently setting up an experimental investigation to observe strain localization during crack propagation (transformation and martensitic saturation regions) on NiTi thin sheets.
The Journal of Arthroplasty, 2022
Background: Unicompartmental knee arthroplasty (UKA) is a procedure with low morbidity and fast r... more Background: Unicompartmental knee arthroplasty (UKA) is a procedure with low morbidity and fast recovery. Anatomic implants or robotic-assisted UKA has been proposed to improve outcomes with precise positioning. Femoral component position (FCP) relative to the tibial insert could be a factor influencing the contact stresses. We aimed to evaluate the effect of the FCP relative to the tibial insert on clinical outcomes and stress distribution after medial UKA. Methods: Sixty-two medial fixed-bearing UKAs were evaluated at a minimum two-year follow-up using the Knee Society Score. Postoperative radiological evaluation performed on frontal X-rays classified the FCP relative to the tibial insert into the following: group M (medial), group C (central), and group L (lateral). A finite element model was developed to evaluate the biomechanical effects of the FCP relative to the tibial component. Results: The postoperative radiological evaluation showed 9 cases in group M, 46 cases in group C, and 7 cases in group L. The maximum knee flexion angle and the 2-year postoperative "symptom" and "patient satisfaction" scores of the Knee Society Score were significantly higher in group C. Compared with central positioning, a shift along the mediolateral axis leads to a displacement of the contact pressure center. Conclusion: The FCP relative to the tibial insert may increase patient outcomes at a minimum follow-up of two years after fixed-bearing medial UKA. Accordance between FCP and contact stresses on the polyethylene insert could be a contributing factor of long-term survival of UKA.
The objective of the European Commission Project "MOONWALK" (H2020) was to develop robotastronaut... more The objective of the European Commission Project "MOONWALK" (H2020) was to develop robotastronaut cooperation techniques and test those in two specific analogue missions: one in Rio Tinto, Spain and another one underwater offshore Marseilles. In the frame of the project, a team of seven partners developed a simulation architecture including space suit simulators ("GANDOLFI"), a robotic scout vehicle ("YEMO"), biomonitoring techniques, sampling tools and a communication architecture allowing communication with a distance Mission Control Centre (MCC) based in Zaventem, Belgium. The paper and presentation will report on the mission simulations in Rio Tinto (Mars Mission) and Marseilles (Lunar mission). It will show the results of the project and give a vision on future work in this field where the test platforms developed in MOONWALK could be used for research or astronaut training.
Materiaux incontournables des materiaux fonctionnels, les alliages a memoire de forme(AMF) peuven... more Materiaux incontournables des materiaux fonctionnels, les alliages a memoire de forme(AMF) peuvent presenter de tres larges deformations reversibles. La Transformation de Phase Martensitique (TPM), ayant lieu lorsqu’il est soumis a une action mecanique ou thermique, lui confere des caracteristiques particulieres. Le comportement thermomecanique des AMF est a present bien maitrise. Cependant la connaissance de leur comportement `a la rupture reste un enjeu majeur pour leur dimensionnement dans le cadre de leur industrialisation perenne. Ces travaux de recherche se sont attaches `a la connaissance, la description et la quantification du phenomene de localisation en pointe de fissure liee a la TPM induite sous contrainte, au travers du developpement d’un modele predictif et de sa correlation experimentale par mesures de champs simultanees lors d’essais de rupture sur des eprouvettes fissurees de NiTi. Deux modeles analytiques bases sur la mecanique lineaire de la rupture, integrant le ...
The thermomechanical behavior of shape memory alloys is now well mastered. However, a hindrance t... more The thermomechanical behavior of shape memory alloys is now well mastered. However, a hindrance to their sustainable use is the lack of knowledge of their fracture behavior. With the aim of filling this partial gap, fracture tests on notched specimens in NiTi have been made. Particular attention was paid to the surfaces detection of phase transformation in the vicinity of the crack tip by kinematic field measurement and their analytical prediction. Mots clefs : alliage a memoire de forme, transformation de phase, rupture, NiTi
Robots are likely to play an important part as support for future human exploration missions on M... more Robots are likely to play an important part as support for future human exploration missions on Mars and Moon. Robotic assistants have the potential to improve the efficiency and safety of human surface activities. The control of robots in space is non-trivial because astronauts are limited in their movements by a bulky spacesuit and missing or reduced gravity. The EU funded project Moonwalk investigates technologies for robotic crew assistance and methods for performing earth analogue simulations. A hybrid leg/wheel system is used as the robotic platform, which is equipped with an omnidirecional camera to monitor the astronaut. The robot can be controlled by gestures which are detected with sensors attached to the human. In this paper we present the requirements, progress and outlook on the robotic system and the supporting technologies.
Aerosol Science and Engineering, 2020
Microbial aerosols can be used as model particles for examining the dispersion and deposition of ... more Microbial aerosols can be used as model particles for examining the dispersion and deposition of particles as well as assessing the reliability of the simulation methods. For example, the computational fluid dynamics model (CFD) can be used in the evaluation of indoor microbial contamination and the possible spread of harmful microbes in spaces with high densities of people or in special hermetic environments. The aim of this study was to compare the results of the CFD simulation, which predicts the deposition of biological particles on the surfaces of a spacecraft, and real particle deposition, usingBacillus licheniformis/aeriusbacterium particles as the model organism. The results showed that the particles were mainly deposited on floor surfaces, but also onto the supply air diffusers, where bacterial concentrations were higher than on the wall and ceiling surfaces. The CFD simulation showed similar trends with actual particle dispersal, conducted in this experiment withBacilluspa...
Neuroscience, 2016
Astronauts' training is conventionally performed in a pool to reproduce weightlessness by exploit... more Astronauts' training is conventionally performed in a pool to reproduce weightlessness by exploiting buoyancy which is supposed to reduce the impact of gravity on the body. However, this training method has not been scientifically validated yet, and requires first to study the effects of underwater exposure on motor behavior. We examined the influence of neutral buoyancy on kinematic features of whole-body reaching underwater and compared them with those produced on land. Eight professional divers were asked to perform arm reaching movements toward visual targets while standing. Targets were presented either close or far from the subjects (requiring in the latter case an additional whole-body displacement). Reaching movements were performed on land or underwater in two different contexts of buoyancy. The divers either wore a diving suit only with neutral buoyancy applied to their center of mass or were additionally equipped with a submersible simulated space suit with neutral buoyancy applied to their body limbs. Results showed that underwater exposure impacted basic movement features, especially movement speed which was reduced. However, movement kinematics also differed according to the way buoyancy was exerted on the whole-body. When neutral buoyancy was applied to the center of mass only, some focal and postural components of whole-body reaching remained close to land observations, notably when considering the relative deceleration duration of arm elevation and concomitant forward trunk bending when reaching the far target. On the contrary, when neutral buoyancy was exerted on body segments, movement kinematics were close to those reported in weightlessness, as reflected by the arm deceleration phase and the whole-body forward displacement when reaching the far target. These results suggest that astronauts could benefit from the application of neutral buoyancy across the wholebody segments to optimize underwater training and acquire specific motor skills which will be used in space.
A new phase transformation zone around the crack tip is proposed for shape memory alloys. The pre... more A new phase transformation zone around the crack tip is proposed for shape memory alloys. The present analysis integrates the asymmetry between tension and compression in its yield criterion. Modes I, II and III are predicted. Mode I fracture tests are performed with a particular attention devoted on temperature field evolution around the crack tip. Mots clefs : Mécanique de la rupture, alliages à mémoire de forme, transformation de phase.
AIAA SPACE 2014 Conference and Exposition, 2015
ABSTRACT
AIAA SPACE 2015 Conference and Exposition, 2015
This paper describes simulation mission scenarios which focus on human-robot collaboration. Furth... more This paper describes simulation mission scenarios which focus on human-robot collaboration. Further, it explains the technologies developed for project Moonwalk and describes possible evaluation methods to be able to evaluate the outcome of two trials in different environments, one reflecting a Lunar and the other, a Martian environment. Moonwalk develops new, practical methods for the interaction between astronauts and robots. In earth-analogue simulations of missions to Moon and Mars, one of the challenges is the simulation of operational constraints such as the reduced gravity or the communication delay between the astronauts and mission control on Earth. In project Moonwalk, two analogue simulations are planned for the conditions that astronauts will encounter during future extravehicular activities (EVA) on planetary surfaces: firstly, simulations subsea and offshore the coast of the French city of Marseilles will be conducted, where an EVA on the lunar surface under reduced gravity will be performed. A second simulation will be conducted in the Spanish region of Rio Tinto (an established Martian analogue site), where operations are focusing on exobiological sampling and sampling procedures under extreme environmental conditions. For these simulation missions specific scenarios for human-robot collaboration have been developed to be performed, compared and evaluated.
Defect and Diffusion Forum, 2008
Classically a master curve as Dorn's equation is applied for elucidating stationary creep beh... more Classically a master curve as Dorn's equation is applied for elucidating stationary creep behaviour within high temperature range (T > 0.6 Tm). As the diffusion of both 63Ni and 44Ti have been measured in an equiatomic NiTi, an effective choice of creep-relevant diffusion coefficient D may be possible. Moreover, creep measurements in the same temperature range performed can be found in the literature. The correlation does not permit to establish precisely what D coefficient to integrate in the Dorn's equation.
ESOMAT 2009 - 8th European Symposium on Martensitic Transformations, 2009
A new analytical prediction of the phase transformation zone around the crack tip is proposed for... more A new analytical prediction of the phase transformation zone around the crack tip is proposed for shape memory alloys. The present analysis integrates the asymmetry between tension and compression in the yield surface of phase transformation around the crack tip. Shapes and sizes of the phase transformation zone are predicted for loading modes I, II and III. Furthermore, an experimental investigation for mode I loading fracture tests on edgecracked specimens of a nickel-titanium alloy is currently performing with a particular attention devoted on displacement and temperature fields evolution around the crack tip. The use of shape memory alloys (SMAs), for instance smart structures actuators, has a great appeal for industrial applications, mostly in medical device or aeronautics. SMAs own very large recoverable strains (of the order of 8% for NiTi alloys) as a result of a phase transformation from austenite to martensite. Thus, the investigation of the SMAs fracture is a relevant question in order to improve service life of systems. The linear elastic fracture mechanics (LEFM) theory allows knowing the stress field around the crack tip which depends on the loading mode. Theoretically, the stress field around the crack tip is unbounded. However, as usual elastic materials undergo yielding at the crack tip, SMAs accommodate the applied stress through a material phase change. If a sheet initially in the austenic state is mechanical loaded, applied stress induces the creation of a martensitic phase transformation region in the vicinity of the crack tip. In this case, the crack tip region is governed by the stress field associated to the SMA pseudoelastic behaviour.
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Papers by Virginie Taillebot