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damage-plasticity
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The extended finite element method for large deformation ductile fracture problems with a non-local damage-plasticity model
, Article Engineering Fracture Mechanics ; Volume 112-113 , 2013 , Pages 97-125 ; 00137944 (ISSN) ; Khoei, A. R ; Sharif University of Technology
2013
Abstract
An enriched-FEM technique is presented for the crack growth simulation in large deformation ductile fracture problems using a non-local damage-plasticity model in the framework of eXtended Finite Element Method (X-FEM). The Lemaitre damage-plasticity model is used to capture the material degradation effect, in which the non-locality is enforced by solving a Helmholtz type equation in combination with the governing equation of the system based on an operator-split technique. A convergence study is performed to investigate the performance of X-FEM technique in plasticity problems. The accuracy and effectiveness of proposed X-FEM damage-plasticity model are verified through several numerical...
Simulation of high-velocity impact to concrete structures using damage-plasticity model considering large deformation
, Article International Journal of Solids and Structures ; Volume 155 , 2018 , Pages 275-290 ; 00207683 (ISSN) ; Kazemi, M. T ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
In this manuscript, an advanced damage-plasticity model is utilized to simulate response of concrete structures under high-velocity impact. Due to presence of large deformations, it is necessary to incorporate the damage-plasticity model into the finite deformation framework. In high-velocity impact, severe numerical problems could be encountered while updating stress values due to the sudden increase in their levels, especially for the complicated material model used in this study. To overcome these obstacles, an enhancement is made in the nonlinear system of equations of stress- updating procedure. In addition, an adaptive multi-step numerical algorithm is introduced which improves the...
Damage-plasticity model for mixed hinges in steel frames
, Article Journal of Constructional Steel Research ; Volume 67, Issue 8 , 2011 , Pages 1272-1281 ; 0143974X (ISSN) ; Asl, M. H ; Sharif University of Technology
2011
Abstract
A damage-plasticity based mixed axial-shear-flexural (PVM) link element for the inelastic analysis of frames is introduced in this paper. The multi-surfaces yield concept is utilized in the definition of the element. The yield surfaces are defined in deformation space and interaction of axial-shear-flexural deformations is considered by defining non-rectangular yield surfaces. The element is capable of considering damage and post-peak softening behavior. The analytical results of introduced element are verified by existing experimental results of steel beam to column connection and it is indicated that the analytical results have reasonable agreement with the test results. Nonlinear dynamic...
Fracture Modeling of Strengthened Arc Concrete Structures with FRP by Concrete Damage Plasticity and XFEM
, M.Sc. Thesis Sharif University of Technology ; Khoei, Amir Reza (Supervisor)
Abstract
Usage of FRP material is developed in recent year, because advantages of this material researcher studied the effect of this strengthening method on beam column and masonry structures, but few research’s related to RC arches that strengthen with FRP. This studies showed performance of structure properties but many parameters influence. In this research, a model developed that can model RC arch with FRP till complete failure, after verifying model with experimental result parametric study done. This parameter are effect of strengthening scheme, influence of shape of arch and geometry of arches. Concrete damage plasticity used for modeling behavior of concrete, also for modeling interface...
Analytical Problems of Prestressd Post-tensione Concrete Slabs
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
Recently in civil engineering prestressed concrete slab applications is increasing, and typically results in overall economy and provides satisfactory structural performance. In The present work, two-way prestressed concrete slabs have been considered and during designing process with the ACI-2005 code and due to economic plan, prestressed slabs were studied in transfer, service and final conditions. ACI code insists that two-way prestressed slabs shall be classified as class U (without cracking) that means section must be untracked in all conditions (code reference 18.3.3). In addition, two-way prestressed slabs must be prestressed in both directions for 100% of load, and this means that...
Dynamic Modelling of Ductile Damage with Extended Finite Element Method
, Ph.D. Dissertation Sharif University of Technology ; Khoei, Amir Reza (Supervisor)
Abstract
In this thesis, based on the combination of Extended Finite Element Method (X-FEM) and appropriate material constitutive models, an efficient method is proposed to model ductile fracture under quasi-static, cyclic and dynamic conditions. X-FEM is a novel method in which with the use of appropriate enrichment functions, discontinuity geometry is separated from the computational mesh and hence the need for a remeshing step is alleviated. The non-linear material behavior in the crack tip process zone can best be modeled with methods based on continuum damage mechanics. These methods model the ductile fracture mechanisms, phenomenologically. In this thesis, in order to model the ductile...
Seismic evaluation of cemented material dams - A case study of tobetsu dam in Japan
, Article Earthquake and Structures ; Volume 10, Issue 3 , 2016 , Pages 717-733 ; 20927614 (ISSN) ; Noorzad, A ; Ghaemian, M ; Hosseini, A ; Sharif University of Technology
Techno Press
2016
Abstract
Trapezoidal Cemented Sand and Gravel Dam, namely Trapezoid CSG, is a new type of dam. Due to lack of dynamic studies in the field of CSG dam, this research was performed to analyze Trapezoidal CSG dam using dynamic Finite element method with ABAQUS Software. To investigate possible earthquake-induced damages, fragility curves are plotted based on damage index, the length of the cracks created at the dam base and the area of cracked elements in the dam. The seismic analysis indicated that minimum and maximum tensions are generated in the heel and toe of the dam, respectively. According to the fragility curves, with increase in PGA, the possibility of the exceeding the defined limit state is...
Crack Propagation Modeling in Arched Concrete Structures Reinforced by FRP Using XFEM and Damage Model
, M.Sc. Thesis Sharif University of Technology ; Khoei, Amir Reza (Supervisor)
Abstract
In practice, structures made of concrete are full of cracks. The strength of concrete is mainly determined by the tensile strength, which is about 10% of the compressive strength. As long as cracking in concrete is unavoidable, we have to try to minimize their detrimental effects. This objective can be achieved by resisting (or limiting) propagation of existing cracks. Because of this, reinforcement (mostly steel) is used to increase the carrying capacity of the material and to control the development of cracks. Concrete structures that fail, already shows a large number of large and small cracks before their maximum carrying capacity is reached. The failure of concrete can be characterized...
Effect of Carbon and Glass FRP Confinement on Compressive Strength of Pre-Damaged Concrete Cylinders
, M.Sc. Thesis Sharif University of Technology ; Joghatae, Abdolreza (Supervisor)
Abstract
Recent investigations on construction engineering have determined that repairing of Reinforced Concrete (RC) by means of fiber reinforced polymer (FRP) composites is an effective method of retrofitting existing columns. The main research in this thesis focuses on the repair of concrete specimens which are damaged and their initial strength has been reduced. To achieve this purpose, through experimental procedures, the effect of confining damaged concrete cylinders by FRP, has been investigated. The experimental program included three parameters: type of fibers (glass or carbon), type of confining (full or partial), and the number of layers. First concrete cylinders were made and loaded to...
Numerical characterization of anisotropic damage evolution in iron based materials
, Article Scientia Iranica ; Vol. 21, issue. 1 , 2014 , pp. 53-66 ; ISSN: 10263098 ; Javanmardi, M. R ; Azizsoltani, H ; Sharif University of Technology
Abstract
A damage plastic constitutive model for metals is proposed in this paper. An anisotropic damage tensor and a damage surface are adopted to describe the degradation of the mechanical properties of metals. The model is developed within the thermodynamic framework and creates an anisotropic damage plastic model with the ability to describe the plastic and damage behavior of iron based materials. According to the principle of strain energy equivalence between the undamaged and damaged materials, the linear elastic constitutive equations for the damaged material expressed a stiffness tensor in the damaged configuration. The damaged material is modeled using the constitutive laws of the undamaged...