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mixed-mode-fracture
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Dynamic Simulation of Crack Propagation in Concrete Using Lattice Model
, M.Sc. Thesis Sharif University of Technology ; Khoei, Amir Reza (Supervisor)
Abstract
Lattice modeling is one of the most effective methods of simulation of crack initiation and propagation in heterogeneous materials. In this method, not only the impurities can be modeled in detail, but also micro crack initiations and crack ramifications can be observed. Lattice model simulations have shown remarkable results in both force-displacement charts and visual crack formations in heterogeneous materials, especially concrete. Simulation of mechanical behavior of concrete has always been a controversial issue in lattice modeling; and, so far, many researchers have proposed different methods. However, high computation demands, has preserved researchers from any major work on the...
Mixed mode fracture analysis of adiabatic cracks in homogeneous and non-homogeneous materials in the framework of partition of unity and the path-independent interaction integral
, Article Engineering Fracture Mechanics ; Vol. 131, issue , 2014 , Pp. 100-127 ; ISSN: 00137944 ; Bayesteh, H ; Mohammadi, S ; Sharif University of Technology
Abstract
In this paper, the path independent interaction integral has been implemented in the framework of the extended finite element method for mixed mode adiabatic cracks under thermo-mechanical loadings particularly in orthotropic non-homogenous materials. The mesh insensitivity and increased accuracy due to the thermal and displacement asymptotic analytical solutions are discussed and the contour independency of the interaction integral is investigated in different examples. Finally, the problem of crack propagation in orthotropic FGM materials under the thermal loading is investigated to assess the accuracy and robustness of proposed approach
Numerical simulation of multiple crack growth in brittle materials with adaptive remeshing
, Article International Journal for Numerical Methods in Engineering ; Volume 85, Issue 8 , August , 2011 , Pages 1017-1048 ; 00295981 (ISSN) ; Khoei, A. R ; Sharif University of Technology
Abstract
In this paper, an automated adaptive remeshing procedure is presented for simulation of arbitrary shape crack growth in multiple cracked bodies. The Zienkiewicz-Zhu error estimator is employed in conjunction with the modified superconvergent patch recovery (SPR) technique to obtain more accurate estimation of error. A stability analysis is performed to determine active cracks from a set of competitive cracks. Various crack growth criteria together with the respective crack trajectory prediction are compared. Several numerical examples are illustrated to demonstrate the efficiency, robustness and accuracy of computational algorithm in the simulation of multiple crack growth
Multiscale Modeling of Cohesive Crack Growth based on XFEM and Damage Model
, M.Sc. Thesis Sharif University of Technology ; Khoei, Amir Reza (Supervisor)
Abstract
In this research, multi-scale modeling of mixed-mode failure mechanism of quassi-brittle materials is presented. For modeling a realistic crack growth in heterogeneious media, crack initiation criterion, crack growth orientation and the macroscopic cohesive law are derived from a microscopic sample. As a microscopic crack initiation criterion, acoustic tensor is investigated and scaled acoustic tensor has been proposed by comparison its results with maximum principal tensile stress. For crack growth direction based on micro-scale, acoustic tensor and multiscale aggregating discontinuities has been investigated and multiscale aggregating discontinuities by comparison results of these methods...
3D modeling of cohesive crack growth in partially saturated porous media: A parametric study
, Article Engineering Fracture Mechanics ; Vol. 124-125, issue , 2014 , pp. 272-286 ; ISSN: 00137944 ; Khoei, A. R ; Sharif University of Technology
Abstract
In this paper, the 3D cohesive crack propagation is presented in partially saturated porous media. The double-nodded zero-thickness cohesive interface elements are employed to capture the mixed mode fracture behavior. In order to describe the behavior of fractured media, two balance equations are applied similar to those employed for the mixture of solid-fluid phase in semi-saturated media, including: the momentum balance of fractured media, and the balance of fluid mass within the fracture. Crack permeability is modified based on the data obtained from experimental results to consider the roughness of fracture walls effect
The mixed-mode fracture mechanics analysis of an embedded arbitrary oriented crack in a two-dimensional functionally graded material plate
, Article Archive of Applied Mechanics ; Vol. 84, Issue. 5 , 2014 , pp. 625-637 ; ISSN: 0939-1533 ; Kargarnovin, M. H ; Sharif University of Technology
Abstract
Mixed-mode fracture mechanics analysis of an embedded arbitrarily oriented crack in a two-dimensional functionally graded material using plane elasticity theory is considered. The material properties are assumed to vary exponentially in two planar directions. Then, employing Fourier integral transforms with singular integral equation technique, the problem is solved. The stress intensity factors (SIFs) at the crack tips are calculated under in-plane mechanical loads. Finally, the effects of crack orientation, material non-homogeneity, and other parameters are discussed on the value of SIF in mode I and mode II fracture
Crack growth modeling via 3D automatic adaptive mesh refinement based on modified-SPR technique
, Article Applied Mathematical Modelling ; Volume 37, Issue 1-2 , 2013 , Pages 357-383 ; 0307904X (ISSN) ; Eghbalian, M ; Moslemi, H ; Azadi, H ; Sharif University of Technology
2013
Abstract
In this paper, the three-dimensional automatic adaptive mesh refinement is presented in modeling the crack propagation based on the modified superconvergent patch recovery technique. The technique is developed for the mixed mode fracture analysis of different fracture specimens. The stress intensity factors are calculated at the crack tip region and the crack propagation is determined by applying a proper crack growth criterion. An automatic adaptive mesh refinement is employed on the basis of modified superconvergent patch recovery (MSPR) technique to simulate the crack growth by applying the asymptotic crack tip solution and using the collapsed quarter-point singular tetrahedral elements...
Mixed mode fracture in reinforced concrete with low volume fraction of steel fibers
, Article International Journal of Engineering, Transactions B: Applications ; Volume 24, Issue 1 , February , 2011 , Pages 1-18 ; 1728-144X (ISSN) ; Zakeri, I ; Shahvari, F. V ; Sharif University of Technology
Materials and Energy Research Center
2011
Abstract
An investigation into the mixed mode fracture of steel fiber reinforced concrete (SFRC) beams with one percent volume fraction of steel fiber is presented. A series of notched beams with different notch depths and locations are tested under three-point bending. The test results for apparent fracture toughness, crack trajectories, and fracture energy are presented. The crack paths for SFRC and plain concrete beams are compared. The apparent fracture toughness values were more scattered for SFRC than for plain concrete. The load-deflection curves were used to obtain the fracture energy. To this end, two methods were utilized for center notched beams, and the results were comparable to each...
Modeling of dynamic cohesive fracture propagation in porous saturated media
, Article International Journal for Numerical and Analytical Methods in Geomechanics ; Volume 35, Issue 10 , 2011 , Pages 1160-1184 ; 03639061 (ISSN) ; Barani, O. R ; Mofid, M ; Sharif University of Technology
2011
Abstract
In this paper, a mathematical model is presented for the analysis of dynamic fracture propagation in the saturated porous media. The solid behavior incorporates a discrete cohesive fracture model, coupled with the flow in porous media through the fracture network. The double-nodded zero-thickness cohesive interface element is employed for the mixed mode fracture behavior in tension and contact behavior in compression. The crack is automatically detected and propagated perpendicular to the maximum effective stress. The spatial discretization is continuously updated during the crack propagation. Numerical examples from the hydraulic fracturing test and the concrete gravity dam show the...