1,721,035 research outputs found
Multiscale mechanical modelling of complex materials and engineering applications 3
No full textP. TROVALUSCI, B. SCHREFLER, Foreword/
DUY KHANH TRINH, RALF JANICKE, NICOLAS AUFFRAY, STEFAN DIEBELS, SAMUEL FOREST, Evaluation of generalized continuum
substitution models for heterogeneous materials/
SWANTJE BARGMANN, BOB SVENDSEN, Rate variational continuum thermodynamic modeling and simulation of GND-based latent hardening in polycrystals/
DAVID GRÉGOIRE, LAURA B. ROJAS-SOLANO, GILLES PIJAUDIER-CABOT, Continuum to discontinuum transition during failure in non-local damage models/
M. BONGUE BOMA, L. SUDAK, S. FEDERICO, Gradient-dependent constitutive laws for a model of micro-cracked bodies/
IOANIS STEFANOU, JEAN SULEM, Micromorphic Continua: application to the homogenization of diatomic masonry columns/
ELISABETH AIGNER, ROMAN LACKNER AND JOSEF EBERHARDSTEINER, Multiscale viscoelastic-viscoplastic model for the prediction of
permanent deformation in
exible pavements/
DANIELA P.BOSO, M. LEFIK, Definition of the stiffness matrix
of a hierachial structure by using virtual testing and artificial neural network
A numerical approach for static and dynamic analysis of deformable journal bearings
Full text linkThis paper presents a numerical approach for the static and dynamic analysis of hydrodynamic radial journal bearings. In the first part, the effect of shaft and housing deformability on pressure distribution within oil film is investigated. An iterative algorithm that couples Reynolds equation with a finite elements (FE) structural model is solved. Viscosity-to-pressure dependency (Vogel-Barus equation) is also included. The deformed lubrication gap and the overall stress state are obtained. Numerical results are presented with reference to a typical journal bearing configuration at two different inlet oil temperatures. Obtained results show the great influence of bearing components structural deformation on oil pressure distribution, compared with results for ideally rigid components. In the second part, a numerical approach based on perturbation method is used to compute stiffness and damping matrices, which characterize the journal bearing dynamic behavior
Thermo-hydro-mechanical analysis of partially satured porous materials
No full textPresents a fully coupled numerical model to simulate the slow transient phenomena involving heat and mass transfer in deforming partially saturated porous materials. Makes use of the modified effective stress concept together with the capillary pressure relationship. Examines phase changes (evaporation-condensation(, heat transfer through conduction and convection, as well as latent heat transfer. The governing equations in terms of gas pressure, capillary pressure, temperature and displacements are coupled non-linear differential equations and are discretized by the finite element method in space and by finite differences in the time domain. The model is further validated with respect to a documented experiment on partially saturated soil behaviour, and the effects of two-phase flow, as compared to the one-phase flow solution, are analysed. Two other examples involving drying of a concrete wall and thermoelastic consolidation of partially saturated clay demonstrate the importance of proper physical modelling and of appropriate choice of the boundary conditions
A constitutive framework for the description of the thermomehcanical behaviour of clays
No full textAvailable results of novel experimental tests carried out under non-isothermal partially saturated conditions motivate the present study. The goal is to enhance an elastic-plastic model proposed by the authors and to assess its predictive capability with respect to temperature changes. The model is cast within the constitutive framework for partially saturated soils which uses Bishop’s stress and suction as main variables governing the volumetric response of the material. The main features of the proposed formulation are illustrated with the aid of some numerical results
Hygro-thermo-chemo-mechanical modelling of concrete at early ages and beyond. Part II: Shrinkage and creep of concrete
No full textIn Part I of this paper (Int. J. Numer Meth. Eng., in print) a mechanistic model of hygro-thermochemical performance of concrete at early ages has been introduced. Additionally, as compared to the existing models (e.g. J. Eng. Mech. (ASCE) 1995; 121(7):785-794; 1999; 125(9):1018-1027), an effect of relative humidity on cement hydration rate and associated hygro-thermal phenomena have been taken into account. Here we deal with mechanical performance of concrete at early ages and beyond, and in particular, evolution of its strength properties (aging) and deformations (shrinkage and creep strains), described by using the effective stress concept. This allow us for explanation and modelling of phenomena known from experiments, like drying creep (e.g. Mathematical Modeling of Creep and Shrinkage of Concrete. Wiley: Chichester, 1988), or some additional strains, as compared to pure shrinkage, which appear during autogenous deformations of a maturing, sealed concrete sample (e.g. Cement Concrete Res. 2003; 33:223-232). Creep is described by means of the modified microprestress-solidification theory by Bazant et al. (J. Eng. Mech. (ASCE) 1997; 123(11):1188-1194; 1195-1201), with some modifications to take into account the effects of temperature (Comput. Struct. 2002; 80:1511-1521) and relative humidity (Int. J Numer. Meth. Eng., in print; Proceedings of the 5th World Congress for Computational Mechanics (WCCM), Vienna, Austria, 7-12 July 2002), on concrete aging. Shrinkage strains are modelled by using the effective stress principle in the form introduced by Gray and Schrefler (Eur J. Mech. AlSolids 2001; 20:521-538; Appl. Mech. Rev. (ASME) 2002; 55(4):351-388), giving a good agreement with experimental data also for lower values of relative humidity.
Two numerical examples showing comparison of the results obtained by means of our model with some published experimental data are presented. The third one, concerning 2D axial symmetric case, proves numerical robustness of the developed software. All these examples demonstrate the possibilities of the model to analyse both autogenous deformations in maturing concrete and creep phenomena, including drying creep, in concrete elements of different age, sealed or drying, exposed to external load or without any load
Numerical analysis of hygro-thermic behaviour, stresses and damage of concrete at high temperature
No full textA computational analysis of hygro-thermal and mechanical behaviour of concrete structures at high temperature is presented. The evaluation of thermal, hygral and mechanical performance of this material, including damage effects, needs the knowledge of the heat and mass transfer processes. These are simulated within the framework of a coupled model where non-linearities due to high temperatures are accounted for. The constitutive equations are discussed in some detail. The discretization of the governing equations is carried out by Finite Elements in space and Finite Differences in time
The solid stress tensor in porous media mechanics and the Hill-Mandel condition
No full textAn assessment of the stress tensors used currently for the modeling of partially saturated porous media is made which includes concepts like total stress, solid phase stress, and solid pressure. Thermodynamically constrained averaging theory is used to derive the solid phase stress tensor. It is shown that in the upscaling procedure the Hill conditions are satisfied, which is not trivial. The stress tensor is then compared to traditional stress measures. The physical meaning of two forms of solid pressure and of the Biot coefficient is clarified. Finally, a Bishop-Skempton like form of the stress tensor is obtained and a form of the total stress tensor that does not make use of the effective stress concept
Int. Symposium on Multiscale and Multiphysics Modelling for Complex Materials, 6th European Congress on Computational Methods in Applied Sciences and Engineering, ECCOMAS, Wien, September 10-14.
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Multiscale and Multiphysics Modelling for Complex Materials (DOI 10.1007/s11012-014-0031-x).
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