Am J Prev Med

CC999999/Intramural CDC HHS/United States2017-02-19T00:00:00Z26456878PMC531651

A multi-scale computational scheme for anisotropic hydro-mechanical couplings in saturated heterogeneous porous media

This contribution discusses a coupled two-scale framework for hydro-mechanical problems in saturated heterogeneous porous geomaterials. The heterogeneous nature of such materials can lead to an anisotropy of the hydro-mechanical couplings and non-linear effects. Based on an assumed model of the mesostructure, the average macroscopic hydro-mechanical behaviour is extracted by means of a computational homogenisation procedure in a monolithic way. The ingredients needed to upscale the hydro-mechanical couplings are outlined. The two-scale simulation results are compared with direct numerical simulation for the consolidation of a particle-matrix porous material.Structural EngineeringCivil Engineering and Geoscience

Localisation analysis in masonry using Transformation Field Analysis

In the present paper, the Transformation Filed Analysis (TFA) methodology is used in the multi-scale analysis of cracking localisation in masonry. The related assumption of uniform inelastic strain field in each sub-domain allows reducing the computational cost of such computations without significantly compromising on solution accuracy. The relations underlying the TFA averaging scheme are recalled. The evaluation of the corresponding consistent tangent homogenised stiffness, required in acoustic tensor-based localisation analysis, is also derived. The average RVE mechanical response is performed for two sets of micro-mechanical material laws for mortar joints, based on both damage and damage coupled with plasticity. For these two sets of fine-scale laws, localisation analyses are performed for RVEs under stress proportional loading, showing that meaningful average localisation orientations are properly detected by the acoustic tensor-based loss of ellipticity criterion. Furthermore, the capability of the pure damage micromechanical model combined with TFA to reproduce the failure envelope of typically running bond masonry subjected to uniform biaxial loads is demonstrated through a comparison with available experimental data. Finally, the energetic aspects for the selection of localised solutions are discussed. As a result, the TFA-based averaging scheme is shown to yield meaningful homogenised localisation results, thereby allowing envisioning its use in nested multi-scale computations.info:eu-repo/semantics/publishe

Bending effect on the risk for delamination at the reinforcement/matrix interface of 3D woven fabric composite using a shell-like RVE

This paper presents a computational homogenisation-based technique for flexural effects in textile reinforced composite planar shells. An homogenisation procedure is used for the in-plane and the out-of-plane behaviour of three-dimensional woven composite shells, taking the in-plane periodicity of the material into account while relaxing any periodicity tying in the thickness direction. Several types of damage (matrix or reinforcement cracking, delamination, …) can appear in a composite material. In this paper, material non-linear computations are used to assess the importance of bending on the risk for delamination at the reinforcement/matrix interface. The normal and tangential stresses at the interface are computed and a simplified criterion for delamination is used for this purpose. The effect of flexural loading on the stress components responsible for a potential delamination failure mode at the interface is analysed. The values of interface stresses obtained by means of flexural homogenisation are compared with 3D homogenisation results using periodicity constraints along the thickness direction, and compared qualitatively with experimental facts available from the literature. The importance for taking flexural effects into account properly is emphasised.SCOPUS: ar.jinfo:eu-repo/semantics/publishe