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Title: | Identification of effective elastic properties of fractured rock using extended finite element method | Authors: | Quan Vo Hoang | Keywords: | Heterogeneous materials;Representative volume elements;Boundary conditions | Issue Date: | 2018 | Publisher: | Vietnamese - German University | Abstract: | In order to find the effective properties of heterogeneous materials, they need to undergo a process called homogenization. Several methods of homogenization have been created over the last century and some have attained efficient and accurate approximations of linear elastic properties of heterogeneous materials. Nowadays, numerical methods are widely used for the homogenization of heterogeneous materials by using Representative Volume Elements (RVEs). An RVE should be large enough to contain sufficient information about the microstructure and define overall quantities such as stress and strain, however its size should also be small enough in order not to hide macroscopic heterogeneity [1]. Based on these requirements, it shows that there are two separate scale problems for RVEs, one focuses on the behavior of the material at microscopic scale with heterogeneity, all the micro structures geometries and boundary conditions have to be described accurately. In second scale problem, material is considered homogeneous at macro scale with the properties which are calculated from the first scale problem. After selecting proper size of RVEs, boundary conditions (BCs) which are employed for calculation need to be defined, there are three types of BCs on the microscopic scale: Dirichlet BCs (displacement boundary condition), Neumann BCs (constant traction boundary condition) and periodic BCs. While Dirichlet BCs shows the upper bound of effective elastic moduli, the Neumann BCs shows the lower bound of elastic moduli and the periodic BCs estimates the values in the middle of two bounds [2]. In this paper, with the aim of reducing the effort of using the complex mesh layout to capture the discontinuities inside domain, for instance, cracks, void fraction, pore, etc. As a result Extended Finite Element Method (XFEM) is used to calculate the approximate effective elastic moduli of fractured rock. The findings from t his numerical method then are used to make the comparison of accuracy to the one produced by the Finite Element Method (FEM) [3]. The Object-oriented programming (OOP) language JAVA is used for implementing the overall XFEM code in this thesis, obtained stresses by this code will be verified by module XFEM in Abaqus |
URI(1): | http://epub.vgu.edu.vn/handle/dlibvgu/747 |
Appears in Collections: | Computational Engineering (CompEng) |
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