Publications

2015

• Two coexisting mechanisms of irreversible deformation : crystal plasticity and grains boundary sliding - the case of sodium chloride
  
  • Raphanel Jean
  • Dimanov Alexandre
  • Bornert Michel
  • Bourcier Mathieu
  • Gaye Ababacar
  • D. Picard
  , 2015.
• Reconstruction of a constitutive law for rubber from in silico experiments using Ogden's laws
  
  • de Buhan Maya
  • Gloria Antoine
  • Le Tallec Patrick
  • Vidrascu Marina
  International Journal of Solids and Structures, Elsevier, 2015, pp.16. This article deals with the following data assimilation problem: construct an analytical approximation of a numerical constitutive law in three-dimensional nonlinear elasticity. More precisely we are concerned with a micro-macro model for rubber. Macroscopic quantities of interest such as the Piola-Kirchhoff stress tensor can be approximated for any value of the strain gradient by numerically solving a nonlinear PDE. This procedure is however computationally demanding. Hence, although conceptually satisfactory, this physically-based model is of no direct practical use. The aim of this article is to circumvent this difficulty by proposing a numerical strategy to reconstruct from in silico experiments an accurate analytical proxy for the micro-macro constitutive law. (10.1016/j.ijsolstr.2015.02.026)
  DOI : 10.1016/j.ijsolstr.2015.02.026
• Highly reproducible, hysteresis-free, flexible strain sensors by inkjet printing of carbon nanotubes
  
  • Michelis Fulvio
  • Bodelot Laurence
  • Bonnassieux Yvan
  • Lebental Bérengère
  Carbon, Elsevier, 2015, 95, pp.pp 1020-1026. In order to build upon the exceptional interest for flexible sensors based on carbon nanotube networks (CNNs), the field requires high device-to-device reproducibility. Inkjet printing has provided outstanding results for flexible ohmic sensors in terms of reproducibility of their resistance. However, the reproducibility of the sensitivity, the most critical parameter for sensing application, has been only marginally assessed. In the present paper, CNN based resistive strain sensors fabricated by inkjet-printing on flexible Ethylene Tetrafluoroethylene (EFTE) sheets are presented. The variability on the device initial resistance is studied for 5 different batches of sensors from 3 to 72 devices each. The variability ranges between 8.4% and 43% depending on the size of the batches, with a 20% average. An 8-device batch with 15% variability on initial resistance is further studied for variability on the strain and thermal sensitivity. Standard deviation values are found to be as low as 16% on the strain sensitivity and 8% on the temperature sensitivity. Moreover, the devices are hysteresis free, a rare achievement for CNT strain sensors on plastics. (10.1016/j.carbon.2015.08.103)
  DOI : 10.1016/j.carbon.2015.08.103
• Mechanics of collective unfolding
  
  • Caruel Matthieu
  • Allain Jean-Marc
  • Truskinovsky Lev
  Journal of the Mechanics and Physics of Solids, Elsevier, 2015, 76, pp.237 - 259. Mechanically induced unfolding of passive crosslinkers is a fundamental biological phenomenon encountered across the scales from individual macro-molecules to cytoskeletal actin networks. In this paper we study a conceptual model of athermal load-induced unfolding and use a minimalistic setting allowing one to emphasize the role of long-range interactions while maintaining full analytical transparency. Our model can be viewed as a description of a parallel bundle of N bistable units confined between two shared rigid backbones that are loaded through a series spring. We show that the ground states in this model correspond to synchronized, single phase configurations where all individual units are either folded or unfolded. We then study the fine structure of the wiggly energy landscape along the reaction coordinate linking the two coherent states and describing the optimal mechanism of cooperative unfolding. Quite remarkably, our study shows the fundamental difference in the size and structure of the folding-unfolding energy barriers in the hard (fixed displacements) and soft (fixed forces) loading devices which persists in the continuum limit. We argue that both, the synchronization and the non-equivalence of the mechanical responses in hard and soft devices, have their origin in the dominance of long-range interactions. We then apply our minimal model to skeletal muscles where the power-stroke in acto-myosin crossbridges can be interpreted as passive folding. A quantitative analysis of the muscle model shows that the relative rigidity of myosin backbone provides the long-range interaction mechanism allowing the system to effectively synchronize the power-stroke in individual crossbridges even in the presence of thermal fluctuations. In view of the prototypical nature of the proposed model, our general conclusions pertain to a variety of other biological systems where elastic interactions are mediated by effective backbones. (10.1016/j.jmps.2014.11.010)
  DOI : 10.1016/j.jmps.2014.11.010
• Numerical investigation on corner singularities in cracked plates using the G-theta method with an adapted theta field
  
  • Vu Minh Ngoc
  • Geniaut Samuel
  • Massin Patrick
  • Marigo Jean-Jacques
  Theoretical and Applied Fracture Mechanics, Elsevier, 2015, 77, pp.59-68. G-theta method with appropriate virtual crack extension (theta field) is proposed for the accurate evaluation of energy release rate along a crack edge which is non-orthogonal to the free surface. This method is implemented in the framework of finite element procedure as well as extended finite element one. This numerical procedure is then applied to investigate the corner singularities in cracked plates. The superposition of numerical solution to asymptotic solution within the boundary layer of crack front allows showing the dependence of vertex singularity to plate thickness. (10.1016/j.tafmec.2015.02.003)
  DOI : 10.1016/j.tafmec.2015.02.003
• Dynamics of a spherical capsule in a planar hyperbolic flow: influence of bending resistance
  
  • Dupont Claire
  • Le Tallec P
  • Barthes-Biesel Dominique
  • Vidrascu Marina
  • Salsac A.-V
  , 2015, 16. We consider an initially spherical capsule freely suspended in a planar hyperbolic flow and study the influence of the wall bending resistance on the capsule dynamics. The capsule wall is assumed to be made of a three-dimensional homogeneous elastic material. The fluid-structure interaction between the capsule and the external flow is modeled numerically by coupling a boundary integral method with a shell finite element method. It is found that, for given three-dimensional wall mechanical properties, the capsule deformability is drastically reduced as the bending resistance is increased. But, if one expresses the same results as a function of the two-dimensional mechanical properties of the mid-surface, which is how the capsule wall is modeled in the thin-shell model, the capsule deformed shape is identical to the one predicted for a capsule devoid of bending resistance. The bending rigidity is found to have a negligible influence on the shape and deformation: the capsule main deformation mode is thus solely a function of the elastic stretching of the mid-surface. The wall bending resistance still plays a role locally in the regions where buckling occurs. Its influence is studied in the low flow strength regime, for which wrinkling of the wall is observed to persist at steady state. We show that the wrinkle wavelength only depends on the bending number, which compares the relative importance of bending and shearing phenomena, and provide the correlation law. This result is interesting as it allows bending resistance to be estimated from experiments on capsules in a planar hyperbolic flow at low flow strength. (10.1016/j.piutam.2015.03.009)
  DOI : 10.1016/j.piutam.2015.03.009
• On void shape effects of periodic elasto-plastic materials subjected to cyclic loading
  
  • Mbiakop Armel
  • Constantinescu Andrei
  • Danas Kostas
  European Journal of Mechanics - A/Solids, Elsevier, 2015, 49, pp.481-499. Abstract This work investigates the effect of cyclic loading upon periodic elasto-plastic porous materials. The aim is to understand the evolution of the underlying microstructure, described here with a single void embedded in a cubic unit-cell. Periodic finite element (FEM) calculations are carried out under a finite strain deformation process keeping the absolute value of the stress triaxiality and the Lode angle constant during the cycle. As a result of the applied loading conditions, the void geometry, both volume and shape, change significantly leading to porosity and void shape ratcheting. The void shape becomes non-spherical from the very first cycle leading to a markedly asymmetric cyclic response of the material. This, in turn, results in an observed maximum stress as a function of the number of cycles. In addition, even though the average applied strains are relatively small, the local strains near the void surface increase significantly inducing a significant localization of the deformation. Finally, several initial void shape configurations are also considered. In the majority of the cases studied, the void evolves into a crack-type shape in the direction of the minimum absolute stress. This, in turn, is consistent with a configuration corresponding to a crack subjected to a mode I cyclic loading. (10.1016/j.euromechsol.2014.09.001)
  DOI : 10.1016/j.euromechsol.2014.09.001
• Non-linear numerical simulation of coiling by elastic finite strain model
  
  • Weisz-Patrault Daniel
  • Ehrlacher Alain
  • Legrand Nicolas
  • Mathey Elliette
  Key Engineering Materials, Trans Tech Publications, 2015, 651-653, pp.1060-1065. The coiling process under traction is considered, with an incoming residual stress profile (that can be sufficiently compressive to make the strip buckle): a flatness defect. This paper details a 3D non-linear numerical simulation taking into account the contact of the strip on itself, with a perfect contact law. The model relies on elastic behavior at finite strain because of large rotations. Even though the behavior is elastic, the yield Von Mises criterion is computed and gives information about flatness defects (plastic zones are approximated by zones where the yield stress is exceeded). Furthermore, the paper aims at very short computation times. The modeling strategy relies (for each time step) on two analytical sub-steps. Numerical minimization procedure is used in order apply weak boundary conditions. Results are discussed with respect to a comprehensive Finite Element simulation and good agreement is observed. (10.4028/www.scientific.net/KEM.651-653.1060)
  DOI : 10.4028/www.scientific.net/KEM.651-653.1060
• About the use of standard integration schemes for X-FEM in solid mechanics plasticity
  
  • Martin Alexandre
  • Esnault J.-B
  • Massin Patrick
  Computer Methods in Applied Mechanics and Engineering, Elsevier, 2015, 283, pp.551-572. Highlights • A new integration method for X-FEM elements cut by an interface is proposed. • The Heaviside function is replaced by an equivalent continuous higher order polynomial function. • A generic numerical strategy to compute this polynomial function is proposed. • This new integration method integrates correctly mechanical fields in elasticity and plasticity. Abstract The introduction of plasticity in an extended finite element (X-FEM) framework is very recent and arises several technical and scientific difficulties due to the moving position of integration points as the crack proceeds if a fixed grid is not used. Currently, the existing analyses in plasticity with X-FEM are limited to monotonic plasticity approximated by non-linear elasticity using the HRR field decomposition. However, such an analysis cannot be applied in fatigue where cyclic plasticity plays a major role in crack propagation. The aim of this study is to tackle one of the difficulties induced by cyclic plastic computation: the projection of the internal variables during crack propagation. The discontinuous Heaviside function in the elements cut by the crack is replaced by a new continuous enrichment function. This new function is polynomial and its degrees and coefficients depend on the type of element and on the position of the interface in the element. The automatic determination of the new enrichment and its introduction in a linear and non-linear framework have been implemented for linear elements in two dimensions and three dimensions and tested with convergence tests in elasticity and plasticity. (10.1016/j.cma.2014.09.028)
  DOI : 10.1016/j.cma.2014.09.028
• Data assimilation of time under-sampled measurements using observers, the wave-like equation example
  
  • Cindea Nicolae
  • Imperiale Alexandre
  • Moireau Philippe
  ESAIM: Control, Optimisation and Calculus of Variations, EDP Sciences, 2015, pp.35. We propose a sequential data assimilation scheme using Luenberger type observers when only some space restricted time under-sampled measurements are available. More precisely, we consider a wave-like equation for which we assume known the restriction of the solution to an open non-empty subset of the spatial domain and for some time samples (typically the sampling step in time is much larger than the time discretization step). To assimilate the available data, two strategies are proposed and analyzed. The first strategy consists in assimilating data only if they are available and the second one in assimilating interpolation of the available data at all the discretization times. In order to tackle the spurious high frequencies which appear when we discretize the wave equation, for both strategies, we introduce a numerical viscous term. In this case, we prove some error estimates between the exact solution and our observers. Numerical simulations illustrate the theoretical results in the case of the one dimensional wave equation. (10.1051/cocv/2014042)
  DOI : 10.1051/cocv/2014042
• A computational approach for the lifetime prediction of cardiovascular balloon-expandable stents
  
  • Auricchio Ferdinando
  • Constantinescu Andrei
  • Conti Michele
  • Scalet Giulia
  International Journal of Fatigue, Elsevier, 2015, 75, pp.69-79. This paper presents a methodology for the numerical fatigue-life assessment of cardiovascular balloon-expandable stents. The methodology is based on a global computational approach composed of a mechanical finite element analysis, followed by a fatigue analysis. The method is applied to a classical 316L stainless steel coronary stent design (i.e., the Medinol/Boston Scientific NIR™ stent). Fatigue criteria based on elastic and plastic shakedown concepts for finite and infinite lifetime are used to predict fatigue crack initiation and are calibrated on experimental data related to 316L stainless steel μm-size components, manufactured as stents. The results from the fatigue analysis allow to discuss several aspects affecting stent lifetime, such as the applied cyclic loading including systolic–diastolic pressurization and bending. The generality of the proposed methodology encourages further investigations of such an approach for its application to other materials or small-scale components. (10.1016/j.ijfatigue.2015.02.002)
  DOI : 10.1016/j.ijfatigue.2015.02.002
• Multi-axial Fatigue Criteria with Length Scale and Gradient Effects
  
  • Zepeng Ma
  • Maitournam Habibou
  • Le Tallec Patrick
  Procedia Engineering, Elsevier, 2015, 133, pp.60 - 71. The objective of the work is first to extend some classic high cycle fatigue (HCF) criteria (as Crossland, Dang Van, Papadopoulos, ...) to take into account a sensitivity of the criteria to stress spatial variations occurring at length scale lg, and second to compare the performances of the extensions through numerical simulations of experimental fatigue tests. After an introduction of the basic criteria and their gradient based extensions proposed by Luu et al., we focus on the Crossland criterion to propose a more practical and simple expression taking into account the gradient of the stress amplitude and the maximum hydrostatic stress. The proposition is then tested and applied to different simple situations: 4-point bending and cantilever rotative bending. The relative errors between the exact solutions and the numerical simulations are estimated. Biaxial bending-torsion tests are also simulated to demonstrate the capabilities of the approach. The generalization of the approach to other multiaxial fatigue criteria is briefly shown through the case of Papadopoulos 2001 proposal. Finally, the present study develops a simple formulation of gradient multi-axial fatigue criteria extending the classical HCF criteria. In this work only stress gradient with a beneficial effect on fatigue have been considered. (10.1016/j.proeng.2015.12.624)
  DOI : 10.1016/j.proeng.2015.12.624
• Criticality in the slowed-down boiling crisis at zero gravity
  
  • Charignon T
  • Lloveras P
  • Chatain D
  • Truskinovsky L
  • Vives E
  • Beysens D
  • Nikolayev Vadim
  Physical Review E, American Physical Society (APS), 2015, 91, pp.053007. Boiling crisis is a transition between nucleate and film boiling. It occurs at a threshold value of the heat flux from the heater called CHF (critical heat flux). Usually, boiling crisis studies are hindered by the high CHF and short transition duration (below 1 ms). Here we report on experiments in hydrogen near its liquid-vapor critical point, in which the CHF is low and the dynamics slow enough to be resolved. As under such conditions the surface tension is very small, the experiments are carried out in the reduced gravity to preserve the conventional bubble geometry. Weightlessness is created artificially in two-phase hydrogen by compensating gravity with magnetic forces. We were able to reveal the fractal structure of the contour of the percolating cluster of the dry areas at the heater that precedes the boiling crisis. We provide a direct statistical analysis of dry spot areas that confirms the boiling crisis at zero gravity as a scale-free phenomenon. It was observed that, in agreement with theoretical predictions, saturated boiling CHF tends to zero (within the precision of our thermal control system) in zero gravity, which suggests that the boiling crisis may be observed at any heat flux provided the experiment lasts long enough. (10.1103/PhysRevE.91.053007)
  DOI : 10.1103/PhysRevE.91.053007
• Ductile shear zone rheology : the viewpoint of experimentally crept lower crustal rocks and analogues
  
  • Dimanov Alexandre
  • Raphanel Jean
  • Bornert Michel
  • Bourcier Mathieu
  • Gaye Ababacar
  • Ludwig Wolfgang
  , 2015.
• Viscoplasticity and grain boundary damage in rock salt investigated by 2D and 3D full field measurements
  
  • Dimanov A.
  • Bornert Michel
  • Bourcier Mathieu
  • Gaye Ababacar
  • D. Picard
  • Gharbi H.
  • Ludwig W.
  • Raphanel J.
  • Sab Karam
  , 2015.
• Ex vivo multiscale quantitation of skin biomechanics in wild-type and genetically-modified mice using multiphoton microscopy
  
  • Bancelin Stéphane
  • Lynch Barbara
  • Bonod-Bidaud Christelle
  • Ducourthial Guillaume
  • Psilodimitrakopoulos Sotiris
  • Dokládal Petr
  • Allain Jean-Marc
  • Schanne-Klein Marie-Claire
  • Ruggiero, Florence
  Scientific Reports, Nature Publishing Group, 2015, 5, pp.17635. Soft connective tissues such as skin, tendon or cornea are made of about 90% of extracellular matrix proteins, fibrillar collagens being the major components. Decreased or aberrant collagen synthesis generally results in defective tissue mechanical properties as the classic form of Elhers-Danlos syndrome (cEDS). This connective tissue disorder is caused by mutations in collagen V genes and is mainly characterized by skin hyperextensibility. To investigate the relationship between the microstructure of normal and diseased skins and their macroscopic mechanical properties, we imaged and quantified the microstructure of dermis of ex vivo murine skin biopsies during uniaxial mechanical assay using multiphoton microscopy. We used two genetically-modified mouse lines for collagen V: a mouse model for cEDS harboring a Col5a2 deletion (a.k.a. pN allele) and the transgenic K14-COL5A1 mice which overexpress the human COL5A1 gene in skin. We showed that in normal skin, the collagen fibers continuously align with stretch, generating the observed increase in mechanical stress. Moreover, dermis from both transgenic lines exhibited altered collagen reorganization upon traction, which could be linked to microstructural modifications. These findings show that our multiscale approach provides new crucial information on the biomechanics of dermis that can be extended to all collagen-rich soft tissues. (10.1038/srep17635)
  DOI : 10.1038/srep17635
• Microstructure and deformation mechanisms of a solid propellant using 1H NMR spectroscopy
  
  • Azoug Aurélie
  • Constantinescu Andrei
  • Nevière Robert
  • Jacob Guy
  Fuel, Elsevier, 2015, 148 (May), pp.39–47. Highly-filled elastomers such as solid propellants exhibit a complex nonlinear viscoelastic behavior. The microstructural origin of this behavior is difficult to ascertain with macroscopic observations. This article aims at identifying the deformation mechanisms of a solid propellant by measuring the change in segmental mobility with deformation. The novelty lies in the use of 1H Nuclear Magnetic Resonance (NMR) spectrometry to investigate the spin–spin relaxation times T2 of a solid propellant. In addition, the effect of strain on T2 is measured using a specific setup transmitting the loading of the tensile machine to the sample inside the NMR apparatus. We compare isolated components, unfilled binders, and solid propellants varying in composition according to a design of experiments. The design of experiments determines the influences of the filler fraction, the amount of curing agents, the plasticizer content, and the presence of filler–binder bonding agents, on the segmental mobilities. The propellant protons can be schematically divided into three segmental mobilities corresponding to distinct relaxation times. The short times correspond to the severely restricted segments situated around cross-links or fillers. The intermediate relaxation times correspond to segments of polymer chains linked at both ends. Finally, the long relaxation times correspond to the highly mobile segments of polymers (dangling ends) and to the plasticizer molecules. The influence of strain on the relaxation times shows that the polymer network is stretched between the fillers while part of the polymer in the sol fraction is immobilized. In addition, chain sliding on the filler surface and breaking of filler–binder links can occur. (10.1016/j.fuel.2015.01.074)
  DOI : 10.1016/j.fuel.2015.01.074
• Gradient damage models coupled with plasticity: Variational formulation and main properties
  
  • Alessi Roberto
  • Marigo Jean‐jacques
  • Vidoli Stefano
  Mechanics of Materials, Elsevier, 2015, 80, pp.351--367. A variational formulation is proposed for a family of elastic–plastic–damage models within the framework of rate-independent materials. That consists first in defining the total energy which contains, in particular, a gradient damage term and a term which represents the plastic dissipation but depends also on damage. Then, the evolution law is deduced from the principles of irreversibility, stability and energy balance. Accordingly, the plastic dissipation term which appears both in the damage criterion and the plastic yield criterion plays an essential role in the damage–plasticity coupling. Suitable constitutive choices on how the plastic yield stress decreases with damage, allows us to obtain a rich variety of coupled responses. A particular attention is paid on the equations which govern the formation of cohesive cracks where the displacement is discontinuous and the plasticity localizes. In the one-dimensional traction test where the solution is obtained in a closed form, we show that, because of damage localization, a cohesive crack really appears at the center of the damage zone before the rupture and the associated cohesive law is obtained in closed form in terms of the constitutive parameters. A Finite Element discrete version of the energy functional is used to simulate a two-dimensional traction test over a rectangular domain with mixed boundary conditions; again a localized band of plastic strain is generated seemingly independent of the mesh size. (10.1016/j.mechmat.2013.12.005)
  DOI : 10.1016/j.mechmat.2013.12.005
• The IVS data input to ITRF2014
  
  • Nothnagel Axel
  • Alef Walter
  • Amagai Jun
  • Andersen Per Helge
  • Andreeva Tatiana
  • Artz Thomas
  • Bachmann Sabine
  • Barache Christophe
  • Baudry Alain
  • Bauernfeind Erhard
  • Baver Karen
  • Beaudoin Christopher
  • Behrend Dirk
  • Bellanger A.
  • Berdnikov Anton
  • Bergman Per
  • Bernhart Simone
  • Bertarini Alessandra
  • Bianco Giuseppe
  • Bielmaier Ewald
  • Boboltz David
  • Böhm Johannes
  • Böhm Sigrid
  • Boer Armin
  • Bolotin Sergei
  • Bougeard Mireille
  • Bourda G.
  • Buttaccio Salvo
  • Cannizzaro Letizia
  • Cappallo Roger
  • Carlson Brent
  • Carter Merri Sue
  • Charlot P.
  • Chen Chenyu
  • Chen Maozheng
  • Cho Jungho
  • Clark Thomas
  • Collioud A.
  • Colomer Francisco
  • Colucci Giuseppe
  • Combrinck Ludwig
  • Conway John
  • Corey Brian
  • Curtis Ronald
  • Dassing Reiner
  • Davis Maria
  • de Vicente Pablo
  • Diakov Alexey
  • Dickey John
  • Diegel Irv
  • Doi Koichiro
  • Drewes Hermann
  • Dube Maurice
  • Elgered Gunnar
  • Engelhardt Gerald
  • Evangelista Mark
  • Fan Qingyuan
  • Fedotov Leonid
  • Fey Alan
  • Figueroa Ricardo
  • Fukuzaki Yoshihiro
  • Gambis Daniel
  • Garcia-Espada Susana
  • Gaume Ralph
  • Gaylard Michael
  • Geiger Nicole
  • Gipson John
  • Gomez Frank
  • Gomez-Gonzalez Jesus
  • Gordon David
  • Govind Ramesh
  • Gubanov Vadim
  • Gulyaev Sergei
  • Haas Ruediger
  • Hall David
  • Halsig Sebastian
  • Hammargren Roger
  • Hase Hayo
  • Heinkelmann Robert
  • Helldner Leif
  • Herrera Cristian
  • Himwich Ed
  • Hobiger Thomas
  • Holst Christoph
  • Hong Xiaoyu
  • Honma Mareki
  • Huang Xinyong
  • Hugentobler Urs
  • Ichikawa Ryuichi
  • Iddink Andreas
  • Ihde Johannes
  • Ilijin Gennadiy
  • Ipatov Alexander
  • Ipatova Irina
  • Ishihara Misao
  • Ivanov D. V.
  • Jacobs Chris
  • Jike Takaaki
  • Johansson Karl-Ake
  • Johnson Heidi
  • Johnston Kenneth
  • Ju Hyunhee
  • Karasawa Masao
  • Kaufmann Pierre
  • Kawabata Ryoji
  • Kawaguchi Noriyuki
  • Kawai Eiji
  • Kaydanovsky Michael
  • Kharinov Mikhail
  • Kobayashi Hideyuki
  • Kokado Kensuke
  • Kondo Tetsuro
  • Korkin Edward
  • Koyama Yasuhiro
  • Krasna Hana
  • Kronschnabl Gerhard
  • Kurdubov Sergey
  • Kurihara Shinobu
  • Kuroda Jiro
  • Kwak Younghee
  • La Porta Laura
  • Labelle Ruth
  • Lamb Doug
  • Lambert Sébastien
  • Langkaas Line
  • Lanotte Roberto
  • Lavrov Alexey
  • Le Bail Karine
  • Leek Judith
  • Li Bing
  • Li Huihua
  • Li Jinling
  • Liang Shiguang
  • Lindqvist Michael
  • Liu Xiang
  • Loesler Michael
  • Long Jim
  • Lonsdale Colin
  • Lovell Jim
  • Lowe Stephen
  • Lucena Antonio
  • Luzum Brian
  • Ma Chopo
  • Ma Jun
  • Maccaferri Giuseppe
  • Machida Morito
  • Macmillan Dan
  • Madzak Matthias
  • Malkin Zinovy
  • Manabe Seiji
  • Mantovani Franco
  • Mardyshkin Vyacheslav
  • Marshalov Dmitry
  • Mathiassen Geir
  • Matsuzaka Shigeru
  • Mccarthy Dennis
  • Melnikov Alexey
  • Michailov Andrey
  • Miller Natalia
  • Mitchell Donald
  • Mora-Diaz Julian Andres
  • Mueskens Arno
  • Mukai Yasuko
  • Nanni Mauro
  • Natusch Tim
  • Negusini Monia
  • Neidhardt Alexander
  • Nicolson George
  • Niell Arthur
  • Nikitin Pavel
  • Nilsson Tobias
  • Ning Tong
  • Nishikawa Takashi
  • Noll Carey
  • Nozawa Kentarou
  • Ogaja Clement
  • Oh Hongjong
  • Olofsson Hans
  • Opseth Per Erik
  • Orfei Sandro
  • Pacione Rosa
  • Pazamickas Katherine
  • Petrachenko William
  • Pettersson Lars
  • Pino Pedro
  • Plank Lucia
  • Ploetz Christian
  • Poirier Michael
  • Poutanen Markku
  • Qian Zhihan
  • Quick Jonathan
  • Rahimov Ismail
  • Redmond Jay
  • Reid Brett
  • Reynolds John
  • Richter Bernd
  • Rioja Maria
  • Romero-Wolf Andres
  • Ruszczyk Chester
  • Salnikov Alexander
  • Sarti Pierguido
  • Schatz Raimund
  • Scherneck Hans-Georg
  • Schiavone Francesco
  • Schreiber Ulrich
  • Schuh Harald
  • Schwarz Walter
  • Sciarretta Cecilia
  • Searle Anthony
  • Sekido Mamoru
  • Seitz Manuela
  • Shao Minghui
  • Shibuya Kazuo
  • Shu Fengchun
  • Sieber Moritz
  • Skjaeveland Asmund
  • Skurikhina Elena
  • Smolentsev Sergey
  • Smythe Dan
  • Sousa Don
  • Sovers Ojars
  • Stanford Laura
  • Stanghellini Carlo
  • Steppe Alan
  • Strand Rich
  • Sun Jing
  • Surkis Igor
  • Takashima Kazuhiro
  • Takefuji Kazuhiro
  • Takiguchi Hiroshi
  • Tamura Yoshiaki
  • Tanabe Tadashi
  • Tanir Emine
  • Tao An
  • Tateyama Claudio
  • Teke Kamil
  • Thomas Cynthia
  • Thorandt Volkmar
  • Thornton Bruce
  • Tierno Ros Claudia
  • Titov Oleg
  • Titus Mike
  • Tomasi Paolo
  • Tornatore Vincenza
  • Trigilio Corrado
  • Trofimov Dmitriy
  • Tsutsumi Masanori
  • Tuccari Gino
  • Tzioumis Tasso
  • Ujihara Hideki
  • Ullrich Dieter
  • Uunila Minttu
  • Venturi Tiziana
  • Vespe Francesco
  • Vityazev Veniamin
  • Volvach Alexandr
  • Vytnov Alexander
  • Wang Guangli
  • Wang Jinqing
  • Wang Lingling
  • Wang Na
  • Wang Shiqiang
  • Wei Wenren
  • Weston Stuart
  • Whitney Alan
  • Wojdziak Reiner
  • Yatskiv Yaroslav
  • Yang Wenjun
  • Ye Shuhua
  • Yi Sangoh
  • Yusup Aili
  • Zapata Octavio
  • Zeitlhoefler Reinhard
  • Zhang Hua
  • Zhang Ming
  • Zhang Xiuzhong
  • Zhao Rongbing
  • Zheng Weimin
  • Zhou Ruixian
  • Zubko Nataliya
  , 2015. Very Long Baseline Interferometry (VLBI) is a primary space-geodetic technique for determining precise coordinates on the Earth, for monitoring the variable Earth rotation and orientation with highest precision, and for deriving many other parameters of the Earth system. The International VLBI Service for Geodesy and Astrometry (IVS, http://ivscc.gsfc.nasa.gov/) is a service of the International Association of Geodesy (IAG) and the International Astronomical Union (IAU). The datasets published here are the results of individual Very Long Baseline Interferometry (VLBI) sessions in the form of normal equations in SINEX 2.0 format (http://www.iers.org/IERS/EN/Organization/AnalysisCoordinator/SinexFormat/sinex.html, the SINEX 2.0 description is attached as pdf) provided by IVS as the input for the next release of the International Terrestrial Reference System (ITRF): ITRF2014. This is a new version of the ITRF2008 release (Bockmann et al., 2009). For each session/ file, the normal equation systems contain elements for the coordinate components of all stations having participated in the respective session as well as for the Earth orientation parameters (x-pole, y-pole, UT1 and its time derivatives plus offset to the IAU2006 precession-nutation components dX, dY (https://www.iau.org/static/resolutions/IAU2006_Resol1.pdf). The terrestrial part is free of datum. The data sets are the result of a weighted combination of the input of several IVS Analysis Centers. The IVS contribution for ITRF2014 is described in Bachmann et al (2015), Schuh and Behrend (2012) provide a general overview on the VLBI method, details on the internal data handling can be found at Behrend (2013). (10.5880/GFZ.1.1.2015.002)
  DOI : 10.5880/GFZ.1.1.2015.002
• Full scale lab testing for the determination of rock bolt contribution to reinforced joint shear strength
  
  • Maiolino S.
  • Pellet Frederic
  , 2015.
• Dynamic testing of concrete under high confined pressure. Influence of saturation ratio and aggregate size
  
  • Forquin Pascal
  • Piotrowska E.
  • Gary G.
  EPJ Web of Conferences, EDP Sciences, 2015, 94, pp.01071. (10.1051/epjconf/20159401071)
  DOI : 10.1051/epjconf/20159401071
• Fatigue of Clip Connectors for Offshore Drilling Risers under the Combined Influence of High Mean Stress and Biaxial Tension
  
  • Gaur Vidit
  • Doquet Véronique
  • Persent Emmanuel
  • Roguet Eléonore
  Procedia Engineering, Elsevier, 2015, 133, pp.90 - 101. Push-pull fatigue tests at various R ratios (σmin/σmax), as well as combined cyclic tension and internal pressure tests with various proportions of each loading were run on a 2.5%Cr-1%Mo steel to investigate separately the effects of a mean stress and of positive stress biaxiality. Fatigue lives were found to decrease with increasing mean stress at fixed biaxiality and a non-linear effect of stress biaxiality on fatigue lives was observed at a fixed R ratio. The damage mechanisms were found to change with both parameters and these modifications were analyzed. Many popular multiaxial fatigue criteria were unable to describe all the data. Thus, a new fatigue criterion based on Gerber’s parabola, has been proposed that captures the evolution of the endurance limit under the combined effect of mean stress and biaxial tension. (10.1016/j.proeng.2015.12.631)
  DOI : 10.1016/j.proeng.2015.12.631
• Influence of bending resistance on the dynamics of a spherical capsule in shear flow
  
  • Dupont Claire
  • Salsac Anne-Virginie
  • Barthes-Biesel Dominique
  • Vidrascu Marina
  • Le Tallec Patrick
  Physics of Fluids, American Institute of Physics, 2015, 27, pp.17. The objective of the paper is to study the effect of wall bending resistance on the motion of an initially spherical capsule freely suspended in shear flow. We consider a capsule with a given thickness made of a three–dimensional homogeneous elastic material. A numerical method is used to model the fluid–structure interactions cou- pling a boundary integral method for the fluids with a shell finite element method for the capsule envelope. For a given wall material, the capsule deformability strongly decreases when the wall bending resistance increases. But, if one expresses the same results as a function of the two–dimensional mechanical properties of the mid–surface, which is how the capsule wall is modeled in the thin–shell model, the capsule deformed shape is identical to the one predicted for a capsule devoid of bending resistance. The bending rigidity is found to have a negligible influence on the overall deformation of an initially spherical capsule, which therefore depends only on the elastic stretching of the mid–surface. Still, the bending resistance of the wall must be accounted for to model the buckling phenomenon, which is observed locally at low flow strength. We show that the wrinkle wavelength is only a function of the wall bending resistance and provide the correlation law. Such results can then be used to infer values of the bending modulus and wall thickness from experiments on spherical capsules in simple shear flow. (10.1063/1.4921247)
  DOI : 10.1063/1.4921247
• Interactions between interfacial sliding, diffuse micro cracking and crystal plasticity in polycrystalline rock salt investigated by 2D and 3D digital image correlation
  
  • Dimanov Alexandre
  • Bornert Michel
  • Bourcier Mathieu
  • Gaye Ababacar
  • D. Picard
  • Héripré Eva
  • Gharbi H.
  • Ludwig Wolfgang
  • Raphanel Jean
  • Sab Karam
  , 2015.
• A New Method Combining Finite Element Analysis and Digital Image Correlation to Assess Macroscopic Mechanical Properties of Dentin
  
  • Wang Wenlong
  • Roubier Nicolas
  • Puel Guillaume
  • Allain Jean-Marc
  • Ingrid C. Infante
  • Attal Jean-Pierre
  • Vennat Elsa
  Materials, MDPI, 2015, 8 (2), pp.535 - 550. A literature review points out a large discrepancy in the results of the mechanical tests on dentin that can be explained by stress and strain assessment during the tests. Errors in these assessments during mechanical tests can lead to inaccurate estimation of the mechanical properties of the tested material. On top of that, using the beam theory to analyze the bending test for thick specimens will increase these experimental errors. After summarizing the results of mechanical tests on dentin in the literature, we focus on bending tests and compare the stress assessment obtained by finite element analysis (FEA) and by beam theory application. We show that the difference between the two methods can be quite large in some cases, leading us to prefer the use of FEA to assess stresses. We then propose a new method based on coupling finite element analysis and digital image correlation (DIC) to more accurately evaluate stress distributions, strain distributions and elastic modulus in the case of a three-point bending test. To illustrate and prove the feasibility of the method, Materials 2015, 8 536 it is applied on a dentinal sample so that mean elastic modulus and maximum tensile stress are obtained (11.9 GPa and 143.9 MPa). Note that the main purpose of this study is to focus on the method itself, and not to provide new mechanical values for dentin. When used in standard mechanical testing of dentin, this kind of method should help to narrow the range of obtained mechanical properties values. (10.3390/ma8020535)
  DOI : 10.3390/ma8020535