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ENGINEERING (1225 journals)                  1 2 3 4 5 6 7 | Last

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 7)
3D Research     Hybrid Journal   (Followers: 19)
AAPG Bulletin     Hybrid Journal   (Followers: 7)
AASRI Procedia     Open Access   (Followers: 14)
Abstract and Applied Analysis     Open Access   (Followers: 3)
Aceh International Journal of Science and Technology     Open Access   (Followers: 2)
ACS Nano     Full-text available via subscription   (Followers: 271)
Acta Geotechnica     Hybrid Journal   (Followers: 7)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 6)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 2)
Acta Scientiarum. Technology     Open Access   (Followers: 3)
Acta Universitatis Cibiniensis. Technical Series     Open Access  
Active and Passive Electronic Components     Open Access   (Followers: 7)
Adaptive Behavior     Hybrid Journal   (Followers: 11)
Adıyaman Üniversitesi Mühendislik Bilimleri Dergisi     Open Access  
Adsorption     Hybrid Journal   (Followers: 4)
Advanced Engineering Forum     Full-text available via subscription   (Followers: 6)
Advanced Science     Open Access   (Followers: 5)
Advanced Science Focus     Free   (Followers: 4)
Advanced Science Letters     Full-text available via subscription   (Followers: 9)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 7)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 18)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 6)
Advances in Complex Systems     Hybrid Journal   (Followers: 7)
Advances in Engineering Software     Hybrid Journal   (Followers: 27)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 16)
Advances in Fuzzy Systems     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 12)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 22)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 10)
Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (Followers: 30)
Advances in Operations Research     Open Access   (Followers: 12)
Advances in OptoElectronics     Open Access   (Followers: 5)
Advances in Physics Theories and Applications     Open Access   (Followers: 13)
Advances in Polymer Science     Hybrid Journal   (Followers: 43)
Advances in Porous Media     Full-text available via subscription   (Followers: 5)
Advances in Remote Sensing     Open Access   (Followers: 43)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Aerobiologia     Hybrid Journal   (Followers: 2)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 6)
AIChE Journal     Hybrid Journal   (Followers: 32)
Ain Shams Engineering Journal     Open Access   (Followers: 5)
Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access   (Followers: 1)
Alexandria Engineering Journal     Open Access   (Followers: 1)
AMB Express     Open Access   (Followers: 1)
American Journal of Applied Sciences     Open Access   (Followers: 28)
American Journal of Engineering and Applied Sciences     Open Access   (Followers: 11)
American Journal of Engineering Education     Open Access   (Followers: 9)
American Journal of Environmental Engineering     Open Access   (Followers: 17)
American Journal of Industrial and Business Management     Open Access   (Followers: 23)
Analele Universitatii Ovidius Constanta - Seria Chimie     Open Access  
Annals of Combinatorics     Hybrid Journal   (Followers: 3)
Annals of Pure and Applied Logic     Open Access   (Followers: 2)
Annals of Regional Science     Hybrid Journal   (Followers: 8)
Annals of Science     Hybrid Journal   (Followers: 7)
Antarctic Science     Hybrid Journal   (Followers: 1)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
Applicable Analysis: An International Journal     Hybrid Journal   (Followers: 1)
Applied Catalysis A: General     Hybrid Journal   (Followers: 6)
Applied Catalysis B: Environmental     Hybrid Journal   (Followers: 18)
Applied Clay Science     Hybrid Journal   (Followers: 5)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 12)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 4)
Applied Nanoscience     Open Access   (Followers: 8)
Applied Network Science     Open Access   (Followers: 1)
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Physics Research     Open Access   (Followers: 4)
Applied Sciences     Open Access   (Followers: 3)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 5)
Arabian Journal for Science and Engineering     Hybrid Journal   (Followers: 5)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 5)
Archives of Foundry Engineering     Open Access  
Archives of Thermodynamics     Open Access   (Followers: 8)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
ASEE Prism     Full-text available via subscription   (Followers: 3)
Asia-Pacific Journal of Science and Technology     Open Access  
Asian Engineering Review     Open Access  
Asian Journal of Applied Science and Engineering     Open Access   (Followers: 1)
Asian Journal of Applied Sciences     Open Access   (Followers: 2)
Asian Journal of Biotechnology     Open Access   (Followers: 8)
Asian Journal of Control     Hybrid Journal  
Asian Journal of Current Engineering & Maths     Open Access  
Asian Journal of Technology Innovation     Hybrid Journal   (Followers: 8)
Assembly Automation     Hybrid Journal   (Followers: 2)
at - Automatisierungstechnik     Hybrid Journal   (Followers: 1)
ATZagenda     Hybrid Journal  
ATZextra worldwide     Hybrid Journal  
Australasian Physical & Engineering Sciences in Medicine     Hybrid Journal   (Followers: 1)
Australian Journal of Multi-Disciplinary Engineering     Full-text available via subscription   (Followers: 2)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 9)
Avances en Ciencias e Ingeniería     Open Access  
Balkan Region Conference on Engineering and Business Education     Open Access   (Followers: 1)
Bangladesh Journal of Scientific and Industrial Research     Open Access  
Basin Research     Hybrid Journal   (Followers: 5)
Batteries     Open Access   (Followers: 6)
Bautechnik     Hybrid Journal   (Followers: 1)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 26)
Beni-Suef University Journal of Basic and Applied Sciences     Open Access   (Followers: 4)
BER : Manufacturing Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Motor Trade Survey     Full-text available via subscription   (Followers: 1)
BER : Retail Sector Survey     Full-text available via subscription   (Followers: 2)
BER : Retail Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Survey of Business Conditions in Manufacturing : An Executive Summary     Full-text available via subscription   (Followers: 3)
BER : Survey of Business Conditions in Retail : An Executive Summary     Full-text available via subscription   (Followers: 4)
Bharatiya Vaigyanik evam Audyogik Anusandhan Patrika (BVAAP)     Open Access   (Followers: 1)
Biofuels Engineering     Open Access   (Followers: 1)
Biointerphases     Open Access   (Followers: 1)
Biomaterials Science     Full-text available via subscription   (Followers: 11)
Biomedical Engineering     Hybrid Journal   (Followers: 15)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 14)
Biomedical Engineering Letters     Hybrid Journal   (Followers: 5)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 18)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 34)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 5)
Biomedical Microdevices     Hybrid Journal   (Followers: 9)
Biomedical Science and Engineering     Open Access   (Followers: 4)
Biomedizinische Technik - Biomedical Engineering     Hybrid Journal  
Biomicrofluidics     Open Access   (Followers: 4)
BioNanoMaterials     Hybrid Journal   (Followers: 2)
Biotechnology Progress     Hybrid Journal   (Followers: 39)
Boletin Cientifico Tecnico INIMET     Open Access  
Botswana Journal of Technology     Full-text available via subscription   (Followers: 1)
Boundary Value Problems     Open Access   (Followers: 1)
Brazilian Journal of Science and Technology     Open Access   (Followers: 2)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 10)
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (Followers: 14)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (Followers: 14)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers, Droit, Sciences et Technologies     Open Access  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Hybrid Journal   (Followers: 30)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 44)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 7)
Case Studies in Thermal Engineering     Open Access   (Followers: 5)
Catalysis Communications     Hybrid Journal   (Followers: 6)
Catalysis Letters     Hybrid Journal   (Followers: 2)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 8)
Catalysis Science and Technology     Free   (Followers: 8)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysis Today     Hybrid Journal   (Followers: 7)
CEAS Space Journal     Hybrid Journal   (Followers: 2)
Cellular and Molecular Neurobiology     Hybrid Journal   (Followers: 3)
Central European Journal of Engineering     Hybrid Journal   (Followers: 1)
CFD Letters     Open Access   (Followers: 6)
Chaos : An Interdisciplinary Journal of Nonlinear Science     Hybrid Journal   (Followers: 2)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 2)
Chinese Journal of Engineering     Open Access   (Followers: 2)
Chinese Science Bulletin     Open Access   (Followers: 1)
Ciencia e Ingenieria Neogranadina     Open Access  
Ciencia en su PC     Open Access   (Followers: 1)
Ciencias Holguin     Open Access   (Followers: 1)
CienciaUAT     Open Access  
Cientifica     Open Access  
CIRP Annals - Manufacturing Technology     Full-text available via subscription   (Followers: 11)
CIRP Journal of Manufacturing Science and Technology     Full-text available via subscription   (Followers: 14)
City, Culture and Society     Hybrid Journal   (Followers: 24)
Clay Minerals     Full-text available via subscription   (Followers: 10)
Clean Air Journal     Full-text available via subscription   (Followers: 2)
Coal Science and Technology     Full-text available via subscription   (Followers: 3)
Coastal Engineering     Hybrid Journal   (Followers: 11)
Coastal Engineering Journal     Hybrid Journal   (Followers: 5)
Coatings     Open Access   (Followers: 4)
Cogent Engineering     Open Access   (Followers: 2)
Cognitive Computation     Hybrid Journal   (Followers: 4)
Color Research & Application     Hybrid Journal   (Followers: 2)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 14)
Combustion, Explosion, and Shock Waves     Hybrid Journal   (Followers: 13)
Communications Engineer     Hybrid Journal   (Followers: 1)
Communications in Numerical Methods in Engineering     Hybrid Journal   (Followers: 2)
Components, Packaging and Manufacturing Technology, IEEE Transactions on     Hybrid Journal   (Followers: 28)
Composite Interfaces     Hybrid Journal   (Followers: 7)
Composite Structures     Hybrid Journal   (Followers: 280)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 206)
Composites Part B : Engineering     Hybrid Journal   (Followers: 259)
Composites Science and Technology     Hybrid Journal   (Followers: 200)
Comptes Rendus Mécanique     Full-text available via subscription   (Followers: 2)
Computation     Open Access  
Computational Geosciences     Hybrid Journal   (Followers: 15)
Computational Optimization and Applications     Hybrid Journal   (Followers: 7)
Computational Science and Discovery     Full-text available via subscription   (Followers: 2)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 8)
Computer Science and Engineering     Open Access   (Followers: 19)
Computers & Geosciences     Hybrid Journal   (Followers: 30)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 7)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 5)
Computers and Geotechnics     Hybrid Journal   (Followers: 11)
Computing and Visualization in Science     Hybrid Journal   (Followers: 6)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 33)
Conciencia Tecnologica     Open Access  
Concurrent Engineering     Hybrid Journal   (Followers: 3)
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 8)
Control and Dynamic Systems     Full-text available via subscription   (Followers: 9)
Control Engineering Practice     Hybrid Journal   (Followers: 43)
Control Theory and Informatics     Open Access   (Followers: 8)
Corrosion Science     Hybrid Journal   (Followers: 25)
Corrosion Series     Full-text available via subscription   (Followers: 6)
CT&F Ciencia, Tecnologia y Futuro     Open Access   (Followers: 1)

        1 2 3 4 5 6 7 | Last

Journal Cover Comptes Rendus Mécanique
  [SJR: 0.633]   [H-I: 32]   [2 followers]  Follow
   Full-text available via subscription Subscription journal
   ISSN (Print) 1631-0721
   Published by Elsevier Homepage  [3177 journals]
  • Non-linear vibrations of sandwich viscoelastic shells
    • Abstract: Publication date: Available online 23 February 2018
      Source:Comptes Rendus Mécanique
      Author(s): Lahcen Benchouaf, El Hassan Boutyour, El Mostafa Daya, Michel Potier-Ferry
      This paper deals with the non-linear vibration of sandwich viscoelastic shell structures. Coupling a harmonic balance method with the Galerkin's procedure, one obtains an amplitude equation depending on two complex coefficients. The latter are determined by solving a classical eigenvalue problem and two linear ones. This permits to get the non-linear frequency and the non-linear loss factor as functions of the displacement amplitude. To validate our approach, these relationships are illustrated in the case of a circular sandwich ring.

      PubDate: 2018-02-26T09:58:26Z
  • Helicity and other conservation laws in perfect fluid motion
    • Abstract: Publication date: Available online 21 February 2018
      Source:Comptes Rendus Mécanique
      Author(s): Denis Serre
      In this review paper, we discuss helicity from a geometrical point of view and see how it applies to the motion of a perfect fluid. We discuss its relation with the Hamiltonian structure, and then its extension to arbitrary space dimensions. We also comment about the existence of additional conservation laws for the Euler equation, and its unlikely integrability in Liouville's sense.

      PubDate: 2018-02-26T09:58:26Z
  • Integration of topological modification within the modeling of
           multi-physics systems: Application to a Pogo-stick
    • Abstract: Publication date: Available online 21 February 2018
      Source:Comptes Rendus Mécanique
      Author(s): Nourhene Abdeljabbar Kharrat, Régis Plateaux, Mariem Miladi Chaabane, Jean-Yves Choley, Chafik Karra, Mohamed Haddar
      The present work tackles the modeling of multi-physics systems applying a topological approach while proceeding with a new methodology using a topological modification to the structure of systems. Then the comparison with the Magos' methodology is made. Their common ground is the use of connectivity within systems. The comparison and analysis of the different types of modeling show the importance of the topological methodology through the integration of the topological modification to the topological structure of a multi-physics system. In order to validate this methodology, the case of Pogo-stick is studied. The first step consists in generating a topological graph of the system. Then the connectivity step takes into account the contact with the ground. During the last step of this research; the MGS language (Modeling of General System) is used to model the system through equations. Finally, the results are compared to those obtained by MODELICA. Therefore, this proposed methodology may be generalized to model multi-physics systems that can be considered as a set of local elements.

      PubDate: 2018-02-26T09:58:26Z
  • Influences of the separation distance, ship speed and channel dimension on
           ship maneuverability in a confined waterway
    • Abstract: Publication date: Available online 14 February 2018
      Source:Comptes Rendus Mécanique
      Author(s): Peng Du, Abdellatif Ouahsine, Philippe Sergent
      Ship maneuvering in the confined inland waterway is investigated using the system-based method, where a nonlinear transient hydrodynamic model is adopted and confinement models are implemented to account for the influence of the channel bank and bottom. The maneuvering model is validated using the turning circle test, and the confinement model is validated using the experimental data. The separation distance, ship speed, and channel width are then varied to investigate their influences on ship maneuverability. With smaller separation distances and higher speeds near the bank, the ship's trajectory deviates more from the original course and the bow is repelled with a larger yaw angle, which increase the difficulty of maneuvering. Smaller channel widths induce higher advancing resistances on the ship. The minimum distance to the bank are extracted and studied. It is suggested to navigate the ship in the middle of the channel and with a reasonable speed in the restricted waterway.

      PubDate: 2018-02-26T09:58:26Z
  • Publication list of Jean-Jacques Moreau
    • Abstract: Publication date: Available online 13 February 2018
      Source:Comptes Rendus Mécanique

      PubDate: 2018-02-26T09:58:26Z
  • Impact of local diffusion on macroscopic dispersion in three-dimensional
           porous media
    • Abstract: Publication date: February 2018
      Source:Comptes Rendus Mécanique, Volume 346, Issue 2
      Author(s): Arthur Dartois, Anthony Beaudoin, Serge Huberson
      While macroscopic longitudinal and transverse dispersion in three-dimensional porous media has been simulated previously mostly under purely advective conditions, the impact of diffusion on macroscopic dispersion in 3D remains an open question. Furthermore, both in 2D and 3D, recurring difficulties have been encountered due to computer limitation or analytical approximation. In this work, we use the Lagrangian velocity covariance function and the temporal derivative of second-order moments to study the influence of diffusion on dispersion in highly heterogeneous 2D and 3D porous media. The first approach characterizes the correlation between the values of Eulerian velocity components sampled by particles undergoing diffusion at two times. The second approach allows the estimation of dispersion coefficients and the analysis of their behaviours as functions of diffusion. These two approaches allowed us to reach new results. The influence of diffusion on dispersion seems to be globally similar between highly heterogeneous 2D and 3D porous media. Diffusion induces a decrease in the dispersion in the direction parallel to the flow direction and an increase in the dispersion in the direction perpendicular to the flow direction. However, the amplification of these two effects with the permeability variance is clearly different between 2D and 3D. For the direction parallel to the flow direction, the amplification is more important in 3D than in 2D. It is reversed in the direction perpendicular to the flow direction.

      PubDate: 2018-02-05T08:44:44Z
  • Limit analysis, rammed earth material and Casagrande test
    • Abstract: Publication date: February 2018
      Source:Comptes Rendus Mécanique, Volume 346, Issue 2
      Author(s): Ranime El-Nabouch, Joseph Pastor, Quoc-Bao Bui, Olivier Plé
      The present paper is concerned with the simulation of the Casagrande test carried out on a rammed earth material for wall-type structures in the framework of Limit Analysis (LA). In a preliminary study, the material is considered as a homogeneous Coulomb material, and existing LA static and kinematic codes are used for the simulation of the test. In each loading case, static and kinematic bounds coincide; the corresponding exact solution is a two-rigid-block mechanism together with a quasi-constant stress vector and a velocity jump also constant along the interface, for the three loading cases. In a second study, to take into account the influence of compressive loadings related to the porosity of the material, an elliptic criterion (denoted Cohesive Cam–Clay, CCC) is defined based on recent homogenization results about the hollow sphere model for porous Coulomb materials. Finally, original finite element formulations of the static and mixed kinematic methods for the CCC material are developed and applied to the Casagrande test. The results are the same than above, except that this time the velocity jump depends on the compressive loading, which is more realistic but not satisfying fully the experimental observations. Therefore, the possible extensions of this work towards non-standard direct methods are analyzed in the conclusion section.

      PubDate: 2018-02-05T08:44:44Z
  • Crack identification method in beam-like structures using changes in
           experimentally measured frequencies and Particle Swarm Optimization
    • Abstract: Publication date: February 2018
      Source:Comptes Rendus Mécanique, Volume 346, Issue 2
      Author(s): Samir Khatir, Kevin Dekemele, Mia Loccufier, Tawfiq Khatir, Magd Abdel Wahab
      In this paper, a technique is presented for the detection and localization of an open crack in beam-like structures using experimentally measured natural frequencies and the Particle Swarm Optimization (PSO) method. The technique considers the variation in local flexibility near the crack. The natural frequencies of a cracked beam are determined experimentally and numerically using the Finite Element Method (FEM). The optimization algorithm is programmed in MATLAB. The algorithm is used to estimate the location and severity of a crack by minimizing the differences between measured and calculated frequencies. The method is verified using experimentally measured data on a cantilever steel beam. The Fourier transform is adopted to improve the frequency resolution. The results demonstrate the good accuracy of the proposed technique.

      PubDate: 2018-02-05T08:44:44Z
  • Proper Generalized Decomposition (PGD) for the numerical simulation of
           polycrystalline aggregates under cyclic loading
    • Abstract: Publication date: February 2018
      Source:Comptes Rendus Mécanique, Volume 346, Issue 2
      Author(s): Mohamed Aziz Nasri, Camille Robert, Amine Ammar, Saber El Arem, Franck Morel
      The numerical modelling of the behaviour of materials at the microstructural scale has been greatly developed over the last two decades. Unfortunately, conventional resolution methods cannot simulate polycrystalline aggregates beyond tens of loading cycles, and they do not remain quantitative due to the plasticity behaviour. This work presents the development of a numerical solver for the resolution of the Finite Element modelling of polycrystalline aggregates subjected to cyclic mechanical loading. The method is based on two concepts. The first one consists in maintaining a constant stiffness matrix. The second uses a time/space model reduction method. In order to analyse the applicability and the performance of the use of a space–time separated representation, the simulations are carried out on a three-dimensional polycrystalline aggregate under cyclic loading. Different numbers of elements per grain and two time increments per cycle are investigated. The results show a significant CPU time saving while maintaining good precision. Moreover, increasing the number of elements and the number of time increments per cycle, the model reduction method is faster than the standard solver.

      PubDate: 2018-02-05T08:44:44Z
  • The stochastic energy-Casimir method
    • Abstract: Publication date: Available online 1 February 2018
      Source:Comptes Rendus Mécanique
      Author(s): Alexis Arnaudon, Nader Ganaba, Darryl D. Holm
      In this paper, we extend the energy-Casimir stability method for deterministic Lie–Poisson Hamiltonian systems to provide sufficient conditions for stability in probability of stochastic dynamical systems with symmetries. We illustrate this theory with classical examples of coadjoint motion, including the rigid body, the heavy top, and the compressible Euler equation in two dimensions. The main result is that stable deterministic equilibria remain stable in probability up to a certain stopping time that depends on the amplitude of the noise for finite-dimensional systems and on the amplitude of the spatial derivative of the noise for infinite-dimensional systems.

      PubDate: 2018-02-05T08:44:44Z
  • The legacy of a deep thinker: Jean-Jacques Moreau
    • Abstract: Publication date: Available online 12 January 2018
      Source:Comptes Rendus Mécanique
      Author(s): Emmanuel Villermaux, Pierre Suquet

      PubDate: 2018-02-05T08:44:44Z
  • Stability analysis of internally damped rotating composite shafts using a
           finite element formulation
    • Abstract: Publication date: Available online 12 January 2018
      Source:Comptes Rendus Mécanique
      Author(s): Safa Ben Arab, José Dias Rodrigues, Slim Bouaziz, Mohamed Haddar
      This paper deals with the stability analysis of internally damped rotating composite shafts. An Euler–Bernoulli shaft finite element formulation based on Equivalent Single Layer Theory (ESLT), including the hysteretic internal damping of composite material and transverse shear effects, is introduced and then used to evaluate the influence of various parameters: stacking sequences, fiber orientations and bearing properties on natural frequencies, critical speeds, and instability thresholds. The obtained results are compared with those available in the literature using different theories. The agreement in the obtained results show that the developed Euler–Bernoulli finite element based on ESLT including hysteretic internal damping and shear transverse effects can be effectively used for the stability analysis of internally damped rotating composite shafts. Furthermore, the results revealed that rotor stability is sensitive to the laminate parameters and to the properties of the bearings.

      PubDate: 2018-02-05T08:44:44Z
  • Static and dynamic behaviour of nonlocal elastic bar using integral
           strain-based and peridynamic models
    • Abstract: Publication date: Available online 10 January 2018
      Source:Comptes Rendus Mécanique
      Author(s): Noël Challamel
      The static and dynamic behaviour of a nonlocal bar of finite length is studied in this paper. The nonlocal integral models considered in this paper are strain-based and relative displacement-based nonlocal models; the latter one is also labelled as a peridynamic model. For infinite media, and for sufficiently smooth displacement fields, both integral nonlocal models can be equivalent, assuming some kernel correspondence rules. For infinite media (or finite media with extended reflection rules), it is also shown that Eringen's differential model can be reformulated into a consistent strain-based integral nonlocal model with exponential kernel, or into a relative displacement-based integral nonlocal model with a modified exponential kernel. A finite bar in uniform tension is considered as a paradigmatic static case. The strain-based nonlocal behaviour of this bar in tension is analyzed for different kernels available in the literature. It is shown that the kernel has to fulfil some normalization and end compatibility conditions in order to preserve the uniform strain field associated with this homogeneous stress state. Such a kernel can be built by combining a local and a nonlocal strain measure with compatible boundary conditions, or by extending the domain outside its finite size while preserving some kinematic compatibility conditions. The same results are shown for the nonlocal peridynamic bar where a homogeneous strain field is also analytically obtained in the elastic bar for consistent compatible kinematic boundary conditions at the vicinity of the end conditions. The results are extended to the vibration of a fixed–fixed finite bar where the natural frequencies are calculated for both the strain-based and the peridynamic models.

      PubDate: 2018-02-05T08:44:44Z
  • Classical and sequential limit analysis revisited
    • Abstract: Publication date: Available online 5 January 2018
      Source:Comptes Rendus Mécanique
      Author(s): Jean-Baptiste Leblond, Djimédo Kondo, Léo Morin, Almahdi Remmal
      Classical limit analysis applies to ideal plastic materials, and within a linearized geometrical framework implying small displacements and strains. Sequential limit analysis was proposed as a heuristic extension to materials exhibiting strain hardening, and within a fully general geometrical framework involving large displacements and strains. The purpose of this paper is to study and clearly state the precise conditions permitting such an extension. This is done by comparing the evolution equations of the full elastic–plastic problem, the equations of classical limit analysis, and those of sequential limit analysis. The main conclusion is that, whereas classical limit analysis applies to materials exhibiting elasticity – in the absence of hardening and within a linearized geometrical framework –, sequential limit analysis, to be applicable, strictly prohibits the presence of elasticity – although it tolerates strain hardening and large displacements and strains. For a given mechanical situation, the relevance of sequential limit analysis therefore essentially depends upon the importance of the elastic–plastic coupling in the specific case considered.

      PubDate: 2018-02-05T08:44:44Z
  • Multi-periodic boundary conditions and the Contact Dynamics method
    • Abstract: Publication date: Available online 27 December 2017
      Source:Comptes Rendus Mécanique
      Author(s): Farhang Radjai
      For investigating the mechanical behavior of granular materials by means of the discrete element approach, it is desirable to be able to simulate representative volume elements with macroscopically homogeneous deformations. This can be achieved by means of fully periodic boundary conditions such that stresses or displacements can be applied in all space directions. We present a general framework for periodic boundary conditions in granular materials and its implementation more specifically in the Contact Dynamics method.

      PubDate: 2018-02-05T08:44:44Z
  • Geometrical versus rheological transient creep closure in a salt cavern
    • Abstract: Publication date: November 2017
      Source:Comptes Rendus Mécanique, Volume 345, Issue 11
      Author(s): Pierre Bérest, Mehdi Karimi-Jafari, Benoît Brouard
      An in-situ test performed in a brine-filled cavern proves that, when brine pressure decreases rapidly, the creep closure rate increases drastically. Conversely, a rapid pressure increase leads to “reverse” creep closure: cavern volume increases, even when, at cavern depth, fluid pressure is lower than geostatic pressure. It is tempting to explain these two phenomena by transient salt creep, a characteristic feature of salt rheological behavior commonly observed during laboratory creep tests. In fact, computations performed on an idealized cylindrical cavern excavated from a Norton–Hoff rock mass (a constitutive law that includes no transient component) prove that these two phenomena are, at least partly, of a structural nature: their origin is in the slow redistribution of stresses following any pressure change.

      PubDate: 2018-02-05T08:44:44Z
  • Exact asymptotic relations for the effective response of linear
           viscoelastic heterogeneous media
    • Abstract: Publication date: November 2017
      Source:Comptes Rendus Mécanique, Volume 345, Issue 11
      Author(s): Valentin Gallican, Renald Brenner, Pierre Suquet
      This article addresses the asymptotic response of viscoelastic heterogeneous media in the frequency domain, at high and low frequencies, for different types of elementary linear viscoelastic constituents. By resorting to stationary principles for complex viscoelasticity and adopting a classification of the viscoelastic behaviours based on the nature of their asymptotic regimes, either elastic or viscous, four exact relations are obtained on the overall viscoelastic complex moduli in each case. Two relations are related to the asymptotic uncoupled heterogeneous problems, while the two remaining ones result from the viscoelastic coupling that manifests itself in the transient regime. These results also provide exact conditions on certain integrals in time of the effective relaxation spectrum. This general setting encompasses the results obtained in preceding studies on mixtures of Maxwell constituents [1,2].

      PubDate: 2018-02-05T08:44:44Z
  • A thermo-elastoplastic model for soft rocks considering structure
    • Abstract: Publication date: November 2017
      Source:Comptes Rendus Mécanique, Volume 345, Issue 11
      Author(s): Zuoyue He, Sheng Zhang, Jidong Teng, Yonglin Xiong
      In the fields of nuclear waste geological deposit, geothermy and deep mining, the effects of temperature on the mechanical behaviors of soft rocks cannot be neglected. Experimental data in the literature also showed that the structure of soft rocks cannot be ignored. Based on the superloading yield surface and the concept of temperature-deduced equivalent stress, a thermo-elastoplastic model for soft rocks is proposed considering the structure. Compared to the superloading yield surface, only one parameter is added, i.e. the linear thermal expansion coefficient. The predicted results and the comparisons with experimental data in the literature show that the proposed model is capable of simultaneously describing heat increase and heat decrease of soft rocks. A stronger initial structure leads to a greater strength of the soft rocks. Heat increase and heat decrease can be converted between each other due to the change of the initial structure of soft rocks. Furthermore, regardless of the heat increase or heat decrease, a larger linear thermal expansion coefficient or a greater temperature always leads to a much rapider degradation of the structure. The degradation trend will be more obvious for the coupled greater values of linear thermal expansion coefficient and temperature. Lastly, compared to heat decrease, the structure will degrade more easily in the case of heat increase.

      PubDate: 2018-02-05T08:44:44Z
  • Description analytique complète des limites de l'espace de travail pour
           un manipulateur en série plan
    • Abstract: Publication date: January 2018
      Source:Comptes Rendus Mécanique, Volume 346, Issue 1
      Author(s): Jérôme Bastien
      We give a general and analytical description of plan workspace boundaries, i.e. the boundaries of the part of the space that is reached by the extremity of a human or robot arm. The proposed method is decomposed into three independent steps, for which we do not use calculus of derivatives, determinants and eigenvalues, or numerical resolutions of non-linear problems, which are often used in the literature. The first step, already presented in previous works, consists in interpreting geometrically the necessary Jacobian rank deficiency of the position function at the boundary, and an alignment condition of some joints allows us to determine a union of arcs of circle, which contains the boundary. Then, for all arc of circle, the study of the infinitesimal displacement of a point with regard to this circle allows one to eliminate all or a part of arcs of circle, previously defined, which is not on the boundary. Finally, a global course of the arcs of circle allows us to determine the outer boundary and the inner boundary of the possible void that contains the origin.

      PubDate: 2017-12-26T14:39:31Z
  • The effect of indentation sequence on rock breakages: A study based on
           laboratory and numerical tests
    • Abstract: Publication date: January 2018
      Source:Comptes Rendus Mécanique, Volume 346, Issue 1
      Author(s): Jie Liu, Jun Wang
      Rock may response differently to external loads applied in different sequences. Thus, we conducted indentation tests to investigate the effect of the indentation sequence on rock breakages. Sequential indentations, consuming less indentation energy, usually resulted in larger and deeper grooves and then led to lower specific energies. Thus, we conclude that sequential indentations occur instead of simultaneous indentations form larger grooves with the same indentation energy. To further validate this conclusion, we performed a series of numerical tests. The numerical analysis of stress evolution shows that, for simultaneous indentations, the propagation of an internal crack from an inner rim restrained the propagation of the other internal crack from the other inner rim. However, the chipping pattern varied for sequential indentations. In the first indentation process, an internal crack, initiating from an inner rim, is usually connected with an internal crack caused by the second indentation. The deflection angles of the internal cracks for the sequential indentations were smaller because of the lower compressive stress in the horizontal direction. Then, these smaller deflection angles led to larger chips.

      PubDate: 2017-12-26T14:39:31Z
  • Neural network solution to an inverse problem associated with the
           eigenvalues of the Stokes operator
    • Abstract: Publication date: January 2018
      Source:Comptes Rendus Mécanique, Volume 346, Issue 1
      Author(s): Sebastián Ossandón, Mauricio Barrientos, Camilo Reyes
      A numerical method, based on the design of two artificial neural networks, is presented in order to approximate the viscosity and density features of fluids from the eigenvalues of the Stokes operator. The finite element method is used to solve the direct problem by training a first artificial neural network. A nonlinear map of eigenvalues of the Stokes operator as a function of the viscosity and density of the fluid under study is then obtained. This relationship is later inverted and refined by training a second artificial neural network, solving the aforementioned inverse problem. Numerical examples are presented in order to show the effectiveness and the limitations of this methodology.

      PubDate: 2017-12-26T14:39:31Z
  • A layerwise C0-type higher order shear deformation theory for laminated
           composite and sandwich plates
    • Abstract: Publication date: January 2018
      Source:Comptes Rendus Mécanique, Volume 346, Issue 1
      Author(s): Chien H. Thai, Magd Abdel Wahab, Hung Nguyen-Xuan
      A novel layerwise C0-type higher order shear deformation theory (layerwise C0-type HSDT) for the analysis of laminated composite and sandwich plates is proposed. A C0-type HSDT is used in each lamina layer and the continuity of in-plane displacements and transverse shear stresses at inner-laminar layer is consolidated. The present layerwise theory retains only seven variables without increasing the number of variables when the number of lamina layers are intensified. The shear stresses through the plate thickness derived from the constitutive equation of the present theory have the same shape as those calculated from the equilibrium equation. In addition, the artificial constraints are added in the principle of virtual displacements (PVD) and are certainly fulfilled through a penalty approach. In this paper, two C0-continuity numerical methods, such as the Finite Element Method (FEM) and Bézier isogeometric element (BIEM) are utilized to solve a discrete system of equations derived from the PVD. Several numerical examples with various geometries, aspect ratios, stiffness ratios, and boundary conditions are investigated and compared with the 3D elasticity solution, the analytical, as well as, numerical solutions based on various plate theories.

      PubDate: 2017-12-26T14:39:31Z
  • The Contact Dynamics method: A nonsmooth story
    • Abstract: Publication date: Available online 21 December 2017
      Source:Comptes Rendus Mécanique
      Author(s): Frédéric Dubois, Vincent Acary, Michel Jean
      When velocity jumps are occurring, the dynamics is said to be nonsmooth. For instance, in collections of contacting rigid bodies, jumps are caused by shocks and dry friction. Without compliance at the interface, contact laws are not only non-differentiable in the usual sense but also multi-valued. Modeling contacting bodies is of interest in order to understand the behavior of numerous mechanical systems such as flexible multi-body systems, granular materials or masonry. These granular materials behave puzzlingly either like a solid or a fluid and a description in the frame of classical continuous mechanics would be welcome though far to be satisfactory nowadays. Jean-Jacques Moreau greatly contributed to convex analysis, functions of bounded variations, differential measure theory, sweeping process theory, definitive mathematical tools to deal with nonsmooth dynamics. He converted all these underlying theoretical ideas into an original nonsmooth implicit numerical method called Contact Dynamics (CD); a robust and efficient method to simulate large collections of bodies with frictional contacts and impacts. The CD method offers a very interesting complementary alternative to the family of smoothed explicit numerical methods, often called Distinct Elements Method (DEM). In this paper developments and improvements of the CD method are presented together with a critical comparative review of advantages and drawbacks of both approaches.

      PubDate: 2017-12-26T14:39:31Z
  • Dynamics of a particle with friction and delay
    • Abstract: Publication date: Available online 21 December 2017
      Source:Comptes Rendus Mécanique
      Author(s): Manuel D.P. Monteiro Marques, Raoul Dzonou
      We are interested in the motion of a simple mechanical system having a finite number of degrees of freedom subjected to a unilateral constraint with dry friction and delay effects (with maximal duration τ > 0 ). At the contact point, we characterize the friction by a Coulomb law associated with a friction cone. Starting from a formulation of the problem that was given by Jean-Jacques Moreau in the form of a second-order differential inclusion in the sense of measures, we consider a sweeping process algorithm that converges towards a solution to the dynamical contact problem. The mathematical machinery as well as the general plan of the existence proof may seem much too heavy in order to treat just this simple case, but they have proved useful in more complex settings.

      PubDate: 2017-12-26T14:39:31Z
  • On some features of the effective behaviour of porous solids with J2- and
           J3-dependent yielding matrix behaviour
    • Abstract: Publication date: Available online 19 December 2017
      Source:Comptes Rendus Mécanique
      Author(s): Ahmed Benallal
      Some features od the constitutive behaviour of voided materials taking into account possible effects of the Lode angle in the yielding behaviour of the matrix are discussed. The Gurson approach is used to this end. After providing a parametric representation of the effective behaviour of such materials, some closed-form results are given for pure shear stress states and also at very high stress triaxialities. In the former case corresponding to a zero macroscopic mean stress, the contour of the yield domain in the π-plane has exactly the shape of the yield surface of the matrix in the deviatoric plane, but a size reduced by a factor 1 − f , with f the porosity of the voided material. In the latter, effective yield stresses for the voided material are slightly different from the Gurson result and found to be set by the yield stress at a microscopic stress Lode angle π 3 for very high positive triaxiality and by the yield stress at a microscopic stress Lode angle 0 for very high negative triaxiality. This last result is extended for porous materials with yielding depending further on the hydrostatic stress, fully exhibiting the interaction between volumetric and shear interactions on the yielding behaviour of isotropic porous materials. Applications to many usual yielding criteria for the matrix are also provided.

      PubDate: 2017-12-26T14:39:31Z
  • An overview of the formulation, existence and uniqueness issues for the
           initial value problem raised by the dynamics of discrete systems with
           unilateral contact and dry friction
    • Abstract: Publication date: Available online 15 December 2017
      Source:Comptes Rendus Mécanique
      Author(s): Patrick Ballard, Alexandre Charles
      In the end of the seventies, Schatzman and Moreau undertook to revisit the venerable dynamics of rigid bodies with contact and dry friction in the light of more recent mathematics. One claimed objective was to reach, for the first time, a mathematically consistent formulation of an initial value problem associated with the dynamics. The purpose of this article is to make a review of the today state-of-art concerning not only the formulation, but also the issues of existence and uniqueness of solution.

      PubDate: 2017-12-26T14:39:31Z
  • A duality recipe for non-convex variational problems
    • Abstract: Publication date: Available online 14 December 2017
      Source:Comptes Rendus Mécanique
      Author(s): Guy Bouchitté, Minh Phan
      The aim of this paper is to present a general convexification recipe that can be useful for studying non-convex variational problems. In particular, this allows us to treat such problems by using a powerful primal–dual scheme. Possible further developments and open issues are given.

      PubDate: 2017-12-26T14:39:31Z
  • Settling velocity of quasi-neutrally-buoyant inertial particles
    • Abstract: Publication date: Available online 6 December 2017
      Source:Comptes Rendus Mécanique
      Author(s): Marco Martins Afonso, Sílvio M.A. Gama
      We investigate the sedimentation properties of quasi-neutrally buoyant inertial particles carried by incompressible zero-mean fluid flows. We obtain generic formulae for the terminal velocity in generic space-and-time periodic (or steady) flows, along with further information for flows endowed with some degree of spatial symmetry such as odd parity in the vertical direction. These expressions consist in space-time integrals of auxiliary quantities that satisfy partial differential equations of the advection–diffusion–reaction type, which can be solved at least numerically, since our scheme implies a huge reduction of the problem dimensionality from the full phase space to the classical physical space.

      PubDate: 2017-12-26T14:39:31Z
  • On the self-similar solution to the Euler equations for an incompressible
           fluid in three dimensions
    • Abstract: Publication date: Available online 6 December 2017
      Source:Comptes Rendus Mécanique
      Author(s): Yves Pomeau
      The equations for a self-similar solution to an inviscid incompressible fluid are mapped into an integral equation that hopefully can be solved by iteration. It is argued that the exponents of the similarity are ruled by Kelvin's theorem of conservation of circulation. The end result is an iteration with a nonlinear term entering a kernel given by a 3D integral for a swirling flow, likely within reach of present-day computational power. Because of the slow decay of the similarity solution at large distances, its kinetic energy diverges, and some mathematical results excluding non-trivial solutions of the Euler equations in the self-similar case do not apply.

      PubDate: 2017-12-26T14:39:31Z
  • Recovering convexity in non-associated plasticity
    • Abstract: Publication date: Available online 6 December 2017
      Source:Comptes Rendus Mécanique
      Author(s): Gilles A. Francfort
      We quickly review two main non-associated plasticity models, the Armstrong–Frederick model of nonlinear kinematic hardening and the Drucker–Prager cap model. Non-associativity is commonly thought to preclude any kind of variational formulation, be it in a Hencky-type (static) setting, or when considering a quasi-static evolution because non-associativity destroys convexity. We demonstrate that such an opinion is misguided: associativity (and convexity) can be restored at the expense of the introduction of state variable-dependent dissipation potentials.

      PubDate: 2017-12-26T14:39:31Z
  • An engineering predictive approach of fatigue crack growth behavior: The
           case of the lug-type joint
    • Abstract: Publication date: Available online 7 November 2017
      Source:Comptes Rendus Mécanique
      Author(s): Ahmed Bahloul, Amal Ben Ahmed, Chokri Bouraoui
      The present attempt proposes a predictive approach of the fatigue crack growth (FCG) behavior of a lug-type joint used in an aeronautic context. The crack tip residual stress distribution and material dispersions are considered. The developed approach was implemented by coupling the Extended Finite Element Method (XFEM), the Residual Corrected Stress Intensity Factor (RC-SIF), developed by the authors, and the Monte Carlo simulation (MCS) method. The Lemaitre–Chaboche model, developed upon the ABAQUS commercial code, was considered for characterizing material behavior. The developed approach treats FCG life by considering the stochastic behavior of material parameters and the crack tip residual stress field during propagation. Comparing with experimental data, the proposed approach exhibits a good ability in evaluating the FCG reliability of a cracked lug-type joint subjected to different loading conditions. The iso-probabilistic P–a–N curves can be used as an efficient tool for ensuring the safety behavior of cracked components.

      PubDate: 2017-11-09T10:58:13Z
  • Numerical simulation of rock fragmentation during cutting by conical picks
           under confining pressure
    • Abstract: Publication date: Available online 7 November 2017
      Source:Comptes Rendus Mécanique
      Author(s): Xuefeng Li, Shibo Wang, Shirong Ge, Reza Malekian, Zhixiong Li
      In this article, the effect of confining pressure on rock fragmentation process during cutting was investigated by numerical simulation with a discrete element method (DEM). Four kinds of sandstones with different physical properties were simulated in the rock cutting models under different confining pressures. The rock fragmentation process, the cutting force, and the specific energy under different confining pressures were analyzed. With the increase in confining pressure and rock strength, the vertical propagation of cracks was restrained. Rock samples were compacted and strengthened by confining pressure resulting in the increase of the cutting force. The specific energy of rock cutting linearly increased with the increase of the confining pressure ratio.

      PubDate: 2017-11-09T10:58:13Z
  • Effects of modal truncation and condensation methods on the Frequency
           Response Function of a stage reducer connected by rigid coupling to a
           planetary gear system
    • Abstract: Publication date: Available online 2 November 2017
      Source:Comptes Rendus Mécanique
      Author(s): Marwa Bouslema, Ahmed Frikha, Moez Abdennadhar, Tahar Fakhfakh, Rachid Nasri, Mohamed Haddar
      The present paper is aimed at the application of a substructure methodology, based on the Frequency Response Function (FRF) simulation technique, to analyze the vibration of a stage reducer connected by a rigid coupling to a planetary gear system. The computation of the vibration response was achieved using the FRF-based substructuring method. First of all, the two subsystems were analyzed separately and their FRF were obtained. Then the coupled model was analyzed indirectly using the substructuring technique. A comparison between the full system response and the coupled model response using the FRF substructuring was investigated to validate the coupling method. Furthermore, a parametric study of the effect of the shaft coupling stiffness on the FRF was discussed and the effects of modal truncation and condensation methods on the FRF of subsystems were analyzed.

      PubDate: 2017-11-09T10:58:13Z
  • Frequency analysis of a two-stage planetary gearbox using two different
    • Abstract: Publication date: Available online 31 October 2017
      Source:Comptes Rendus Mécanique
      Author(s): Nabih Feki, Maha Karray, Mohamed Tawfik Khabou, Fakher Chaari, Mohamed Haddar
      This paper is focused on the characterization of the frequency content of vibration signals issued from a two-stage planetary gearbox. To achieve this goal, two different methodologies are adopted: the lumped-parameter modeling approach and the phenomenological modeling approach. The two methodologies aim to describe the complex vibrations generated by a two-stage planetary gearbox. The phenomenological model describes directly the vibrations as measured by a sensor fixed outside the fixed ring gear with respect to an inertial reference frame, while results from a lumped-parameter model are referenced with respect to a rotating frame and then transferred into an inertial reference frame. Two different case studies of the two-stage planetary gear are adopted to describe the vibration and the corresponding spectra using both models. Each case presents a specific geometry and a specific spectral structure.

      PubDate: 2017-11-02T08:51:49Z
  • Harmonic elastic inclusions in the presence of point moment
    • Abstract: Publication date: Available online 26 October 2017
      Source:Comptes Rendus Mécanique
      Author(s): Xu Wang, Peter Schiavone
      We employ conformal mapping techniques to design harmonic elastic inclusions when the surrounding matrix is simultaneously subjected to remote uniform stresses and a point moment located at an arbitrary position in the matrix. Our analysis indicates that the uniform and hydrostatic stress field inside the inclusion as well as the constant hoop stress along the entire inclusion–matrix interface (on the matrix side) are independent of the action of the point moment. In contrast, the non-elliptical shape of the harmonic inclusion depends on both the remote uniform stresses and the point moment.

      PubDate: 2017-11-02T08:51:49Z
  • A folded plate clamped along one side only
    • Abstract: Publication date: Available online 19 October 2017
      Source:Comptes Rendus Mécanique
      Author(s): Serguei A. Nazarov, Andrey S. Slutskij
      An asymptotic model of a folded thin elastic plate is posed on two plane domains and contains transmission conditions at the common line segment of their boundaries. These conditions become non-local and inhomogeneous if only one side of the plate is fixed. Solvability and smoothness results and error estimates for the model are derived.

      PubDate: 2017-10-26T06:36:14Z
  • Stochastic model reduction for robust dynamical characterization of
           structures with random parameters
    • Abstract: Publication date: Available online 6 October 2017
      Source:Comptes Rendus Mécanique
      Author(s): Martin Ghienne, Claude Blanzé, Luc Laurent
      In this paper, we characterize random eigenspaces with a non-intrusive method based on the decoupling of random eigenvalues from their corresponding random eigenvectors. This method allows us to estimate the first statistical moments of the random eigenvalues of the system with a reduced number of deterministic finite element computations. The originality of this work is to adapt the method used to estimate each random eigenvalue depending on a global accuracy requirement. This allows us to ensure a minimal computational cost. The stochastic model of the structure is thus reduced by exploiting specific properties of random eigenvectors associated with the random eigenfrequencies being sought. An indicator with no additional computation cost is proposed to identify when the method needs to be enhanced. Finally, a simple three-beam frame and an industrial structure illustrate the proposed approach.

      PubDate: 2017-10-11T10:40:33Z
  • A constitutive model accounting for strain ageing effects on
           work-hardening. Application to a C–Mn steel
    • Abstract: Publication date: Available online 6 October 2017
      Source:Comptes Rendus Mécanique
      Author(s): Sicong Ren, Matthieu Mazière, Samuel Forest, Thilo F. Morgeneyer, Gilles Rousselier
      One of the most successful models for describing the Portevin–Le Chatelier effect in engineering applications is the Kubin–Estrin–McCormick model (KEMC). In the present work, the influence of dynamic strain ageing on dynamic recovery due to dislocation annihilation is introduced in order to improve the KEMC model. This modification accounts for additional strain hardening rate due to limited dislocation annihilation by the diffusion of solute atoms and dislocation pinning at low strain rate and/or high temperature. The parameters associated with this novel formulation are identified based on tensile tests for a C–Mn steel at seven temperatures ranging from 20 °C to 350 °C. The validity of the model and the improvement compared to existing models are tested using 2D and 3D finite element simulations of the Portevin–Le Chatelier effect in tension.

      PubDate: 2017-10-11T10:40:33Z
  • Mathematical justification of a viscoelastic elliptic membrane problem
    • Abstract: Publication date: Available online 6 October 2017
      Source:Comptes Rendus Mécanique
      Author(s): Gonzalo Castiñeira, Ángel Rodríguez-Arós
      We consider a family of linearly viscoelastic elliptic shells, and we use asymptotic analysis to justify that what we have identified as the two-dimensional viscoelastic elliptic membrane problem is an accurate approximation when the thickness of the shell tends to zero. Most noticeable is that the limit problem includes a long-term memory that takes into account the previous history of deformations. We provide convergence results which justify our asymptotic approach.

      PubDate: 2017-10-11T10:40:33Z
  • Discrete element analysis of the mechanical properties of deep-sea methane
           hydrate-bearing soils considering interparticle bond thickness
    • Abstract: Publication date: Available online 4 October 2017
      Source:Comptes Rendus Mécanique
      Author(s): Mingjing Jiang, Jie He, Jianfeng Wang, Yaping Zhou, Fangyuan Zhu
      Due to increasing global energy demands, research is being conducted on the mechanical properties of methane hydrate-bearing soils (MHBSs), from which methane hydrate (MH) will be explored. This paper presents a numerical approach to study the mechanical properties of MHBSs. The relationship between the level of MH saturation and the interparticle bond thickness is first obtained by analyzing the scanning electron microscope images of MHBS samples, in which is the bridge connecting the micromechanical behavior captured by the DEM with the macroscopic properties of MHBSs. A simplified thermal-hydromechanical (THM) bond model that considers the different bond thicknesses is then proposed to describe the contact behavior between the soil particles and those incorporated into the discrete element method (DEM). Finally, a series of biaxial compression tests are carried out with different MH saturations under different effective confining pressures to analyze the mechanical properties of deep-sea MHBSs. The results of the DEM numerical simulation are also compared with the findings from triaxial compression tests. The results show that the macromechanical properties of deep-sea MHBSs can be qualitatively captured by the proposed DEM. The shear strength, cohesion, and volumetric contraction of deep-sea MHBSs increase with increasing MH saturation, although its influence on the internal friction angle is obscure. The shear strength and volumetric contraction increase with increasing effective confining pressure. The peak shear strength and the dilation of MHBSs increase as the critical bond thickness increases, while the residual deviator stress largely remains the same at a larger axial strain. With increasing the axial strain, the percentage of broken bonds increases, along with the expansion of the shear band.

      PubDate: 2017-10-11T10:40:33Z
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