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Annecy-le-Vieux, France

Taillebot V.,CNRS Femto ST Institute | Lexcellent C.,CNRS Femto ST Institute | Vacher P.,Laboratoire SYMME
Functional Materials Letters | Year: 2012

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 edge-cracked specimens in NiTi have been made. Particular attention was paid to determine the phase transformation zones in the vicinity of the crack tip. In one hand, experimental kinematic fields are observed using digital image correlation showing strain localization around the crack tip. In the other hand, an analytical prediction, based on a modified equivalent stress criterion and taking into account the asymmetric behavior of shape memory alloys in tension-compression, provides shape and size of transformation outset zones. Experimental results are relatively in agreement with our analytical modeling. © 2012 World Scientific Publishing Company. Source


Mansuy M.,Laboratoire SYMME | Giordano M.,Laboratoire SYMME | Davidson J.K.,Arizona State University
Journal of Mechanical Design, Transactions of the ASME | Year: 2013

The major part of production cost of a manufacturing product is set during the design stage and especially by the tolerancing choice. Therefore, a lot of work involves trying to simulate the impact of these choices and provide an automatic optimization. For integrating this modeling in computer aided design (CAD) software, the tolerancing must be modeled by a mathematical tool. Numerous models have been developed but few of them are really efficient. Two advanced models are "T-map" model developed by Joseph K. Davidson and "deviation domain" developed by Max Giordano. Despite the graphical representation of these two models seems to be similar, they have significant differences in their construction and their resolution method. These similarities and differences highlight the needs of tolerancing modeling tool in each kind of problems, especially in case of assembly with parallel links. Copyright © 2013 by ASME. Source


Pottier T.,Laboratoire SYMME | Pottier T.,Chiang Mai University | Toussaint F.,Laboratoire SYMME | Louche H.,Montpellier University | Vacher P.,Laboratoire SYMME
European Journal of Mechanics, A/Solids | Year: 2013

A new method to identify inelastic heat fraction (b factor) evolution models is proposed in this paper. It is based on: (i) simultaneous kinematic and thermal field measurements on heterogeneous tensile tests and (ii) Finite Element Updating (FEU) inverse method. Two inverse calculations, that involve a LevenbergeMarquardt optimization algorithm, are successively used to identify on the one hand the material parameters of a mechanical constitutive model (anisotropic plasticity coefficients and hardening parameters) and on the other hand the plastic power ratio converted into heat. The power balance of the thermomechanical problem is calculated and presented, and the assessment of thermal heat sources is detailed. Finally, six mechanical parameters and four evolution models of b are successively identified for commercially pure titanium. Results confirm a strain dependency of b. © 2012 Elsevier Masson SAS. All rights reserved. Source


Vautrot M.,Laboratoire SYMME | Balland P.,Laboratoire SYMME | Hopperstad O.S.,Norwegian University of Science and Technology | Tabourot L.,Laboratoire SYMME | And 2 more authors.
Technische Mechanik | Year: 2012

This paper presents high-temperature tensile testing. This method is used to characterize the mechanical behaviour of a high-carbon steel C68 at temperatures up to 720°C. Samples are heated by an induction system controlled with a pyrometer. A high-speed camera (500 fps) is used to determine the displacement field with a digital image correlation software. For such tests a specific marking procedure of the sample is applied. Stress-strain curves are given from room temperature up to 720°C at strain rates ranging from 10 -3 /s to 10 -1 /s. Elastic parameters of the material are measured at room temperature using cyclic tests. Bridgman's method is used to determine the equivalent stress-plastic strain curve during the necking phase. Source


Gyliene V.,Kaunas University of Technology | Ostasevicius V.,Kaunas University of Technology | Sergent A.,Laboratoire SYMME
Proceedings - 2011 IEEE International Symposium on Assembly and Manufacturing, ISAM 2011 | Year: 2011

The paper presents results of research of a milling process, which include experimental studies associated with determination of cutting forces. Cutting depth is a parameter that was varied in the course of the measurements. Analytical models were constructed for cutting force prediction on the basis of experimental data obtained for tool geometry, cross-section of removed material layer and cutting regimes. A tool with two inserts was used for milling experiments: during cutting process one insert was removing the material layer, while the other was idle. Analytical models for cutting force evaluation were developed for a single cutting insert. The accuracy of the models was improved by taking into account the specific cutting pressure that was determined experimentally. Chip cross-section varies in the course of the milling process therefore the models allow to estimate cutting forces by adopting the assumption of average chip thickness. Finally, a finite element model was built taking into account the magnitude of material cross-section that is removed during milling operation. © 2011 IEEE. Source

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