Representative elementary volume

About: Representative elementary volume is a research topic. Over the lifetime, 4105 publications have been published within this topic receiving 86863 citations.

Periodic homogenization and consistent estimates of transport parameters through sphere and polyhedron packings in the whole porosity range.

Abstract: This paper presents a study of transport parameters (diffusion, dynamic permeability, thermal permeability, trapping constant) of porous media by combining the homogenization of periodic media (HPM) and the self-consistent scheme (SCM) based on a bicomposite spherical pattern. The link between the HPM and SCM approaches is first established by using a systematic argument independent of the problem under consideration. It is shown that the periodicity condition can be replaced by zero flux and energy through the whole surface of the representative elementary volume. Consequently the SCM solution can be considered as a geometrical approximation of the local problem derived through HPM for materials such that the morphology of the period is "close" to the SCM pattern. These results are then applied to derive the estimates of the effective diffusion, the dynamic permeability, the thermal permeability and the trapping constant of porous media. These SCM estimates are compared with numerical HPM results obtained on periodic arrays of spheres and polyhedrons. It is shown that SCM estimates provide good analytical approximations of the effective parameters for periodic packings of spheres at porosities larger than 0.6, while the agreement is excellent for periodic packings of polyhedrons in the whole range of porosity.

Independent mesh method-based prediction of local and volume average fields in textile composites

Abstract: An independent mesh method (IMM) for three-dimensional stress analysis in composites with complex fiber architectures is proposed. The method represents a combination of direct meshing and voxel-based methodology and allows the modeling of complex tow geometries not readily amenable to traditional finite element meshing. Each fiber tow is meshed independently, while the matrix is meshed throughout the volume of interest. The matrix approximation is then truncated by disregarding the shape functions, whose support is completely inside a tow or completely covered by more than one tow in regions such as tow intersections. The calculation of average stiffness properties of both an oblong fiber-matrix representative volume element (RVE) and a plain weave composite RVE is performed for verification and convergence evaluation purposes. The digital chain technique was used to model fiber architecture in the tri-axial braided composite with high fidelity including the effects of nesting and compaction of plies. Local deformations of the digital architecture due to relief of residual processing stress following a saw cut were predicted by using IMM. These deformations in the tri-axial braided composite were then measured experimentally using Moire interferometry. The degree of agreement between the predicted strain fields and those measured experimentally was shown to correlate with the degree of accuracy of digital architecture and varied from agreement in average behavior to practically point wise agreement across the entire field of measurement.

Discrete element modelling of unidirectional fibre-reinforced polymers under transverse tension

Abstract: The mechanical behaviour of unidirectional fibre-reinforced polymer composites subjected to transverse tension was studied using a two dimensional discrete element method. The Representative Volume Element (RVE) of the composite was idealised as a polymer matrix reinforced with randomly distributed parallel fibres. The matrix and fibres were constructed using disc particles bonded together using parallel bonds, while the fibre/matrix interfaces were represented by a displacement-softening model. The prevailing damage mechanisms observed from the model were interfacial debonding and matrix plastic deformation. Numerical simulations have shown that the magnitude of stress is significantly higher at the interfaces, especially in the areas with high fibre densities. Interface fracture energy, stiffness and strength all played important roles in the overall mechanical performance of the composite. It was also observed that tension cracks normally began with interfacial debonding. The merge of the interfacial and matrix micro-cracks resulted in the final catastrophic fracture.

Steady Couette flows of elastoviscoplastic fluids are nonunique

Abstract: The Herschel–Bulkley rheological fluid model includes terms representing viscosity and plasticity. In this classical model, below the yield stress the material is strictly rigid. Complementing this model by including elastic behavior below the yield stress leads to a description of an elastoviscoplastic (EVP) material such as an emulsion or a liquid foam. We include this modification in a completely tensorial description of cylindrical Couette shear flows. Both the EVP model parameters, at the scale of a representative volume element, and the predictions (velocity, strain and stress fields) can be readily compared with experiments. We perform a detailed study of the effect of the main parameters, especially the yield strain. We discuss the role of the curvature of the cylindrical Couette geometry in the appearance of localization; we determine the value of the localization length and provide an approximate analytical expression. We then show that, in this tensorial EVP model of cylindrical Couette shear f...