scholarly journals Study on Crack Development of Concrete Lining with Insufficient Lining Thickness Based on CZM Method

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7862
Author(s):  
Jian Liu ◽  
Xuesen Zhang ◽  
Gaohang Lv ◽  
Kang Wang ◽  
Bo Han ◽  
...  
Keyword(s):  
Cohesive Zone Model ◽  
Concrete Strength ◽  
Surrounding Rock ◽  
Crack Development ◽  
Concrete Lining ◽  
Failure Behavior ◽  
Zone Model ◽  
Cohesive Elements ◽  
Cracking Behavior ◽  
Operation Period

The most common structural defect of a tunnel in the operation period is the cracking of concrete lining. The insufficient thickness of tunnel lining is one of the main reasons for its cracking. This study studied the cracking behavior of standard concrete specimens and the failure behavior of tunnel structures caused by insufficient lining thickness using Cohesive Zone Model (CZM). Firstly, zero-thickness cohesive elements were globally inserted between solid elements of the standard concrete specimen model, and the crack development process of different concrete grades was compared. On this basis, a three-dimensional numerical model of the tunnel in the operation period was established. The mechanism and characteristics of crack propagation under different lining thicknesses were discussed. In addition, the statistics of cracks were made to discuss the development rules of lining cracks quantitatively. The results show that the CZM can reasonably simulate the fracture behavior of concrete. With the increase in concrete strength grade, the number of cohesive damaged elements and crack area increases. The insufficient lining thickness changes the lining stress distribution characteristics, reduces the lining structure’s overall safety, and leads to the cracking of the diseased area more easily. When surrounding rock does not contact the insufficient lining thickness, its influence on the structure is more evident than when surrounding rock fills the entire lining thickness. The number of cohesive damaged elements and the size of the crack area increases significantly.

scholarly journals COMPUTATION FOR THE DELAMINATION IN THE LAMINATE COMPOSITE MATERIAL USING A COHESIVE ZONE MODEL BY ABAQUS

2020 ◽  
Vol 57 (6A) ◽  
pp. 61
Author(s):  
Hoa Cong Vu
Keyword(s):  
Finite Element ◽  
Cohesive Zone Model ◽  
Constitutive Relations ◽  
Damage Zone ◽  
Damage Model ◽  
Zone Model ◽  
Element Formulation ◽  
Cohesive Elements ◽  
Element Mesh ◽  
Variable Mode

In this paper, a damage model using cohesive damage zone for the simulation of progressive delamination under variable mode is presented. The constitutive relations, based on liner softening law, are using for formulation of the delamination onset and propagation. The implementation of the cohesive elements is described, along with instructions on how to incorporate the elements into a finite element mesh. The model is implemented in a finite element formulation in ABAQUS. The numerical results given by the model are compare with experimental data

scholarly journals Combined Numerical-Statistical Analyses of Damage and Failure of 2D and 3D Mesoscale Heterogeneous Concrete

2015 ◽  
Vol 2015 ◽  
pp. 1-12
Author(s):  
Xiaofeng Wang ◽  
Andrey P. Jivkov
Keyword(s):  
Cohesive Zone Model ◽  
Volume Fraction ◽  
Simulation Method ◽  
Two Dimensions ◽  
Three Dimensions ◽  
Zone Model ◽  
Generation Process ◽  
Cohesive Elements ◽  
Damage And Failure ◽  
2D And 3D

Generation and packing algorithms are developed to create models of mesoscale heterogeneous concrete with randomly distributed elliptical/polygonal aggregates and circular/elliptical voids in two dimensions (2D) or ellipsoidal/polyhedral aggregates and spherical/ellipsoidal voids in three dimensions (3D). The generation process is based on the Monte Carlo simulation method wherein the aggregates and voids are generated from prescribed distributions of their size, shape, and volume fraction. A combined numerical-statistical method is proposed to investigate damage and failure of mesoscale heterogeneous concrete: the geometrical models are first generated and meshed automatically, simulated by using cohesive zone model, and then results are statistically analysed. Zero-thickness cohesive elements with different traction-separation laws within the mortar, within the aggregates, and at the interfaces between these phases are preinserted inside solid element meshes to represent potential cracks. The proposed methodology provides an effective and efficient tool for damage and failure analysis of mesoscale heterogeneous concrete, and a comprehensive study was conducted for both 2D and 3D concrete in this paper.

scholarly journals COMPUTATION FOR THE DELAMINATION IN THE LAMINATE COMPOSITE MATERIAL USING A COHESIVE ZONE MODEL BY ABAQUS

2020 ◽  
Vol 57 (6A) ◽  
pp. 61
Author(s):  
Hoa Cong Vu
Keyword(s):  
Finite Element ◽  
Cohesive Zone Model ◽  
Constitutive Relations ◽  
Damage Zone ◽  
Damage Model ◽  
Zone Model ◽  
Element Formulation ◽  
Cohesive Elements ◽  
Element Mesh ◽  
Variable Mode

In this paper, a damage model using cohesive damage zone for the simulation of progressive delamination under variable mode is presented. The constitutive relations, based on liner softening law, are using for formulation of the delamination onset and propagation. The implementation of the cohesive elements is described, along with instructions on how to incorporate the elements into a finite element mesh. The model is implemented in a finite element formulation in ABAQUS. The numerical results given by the model are compare with experimental data

scholarly journals Crash Analysis of Aluminum/CFRP Hybrid Adhesive Joint Parts Using Adhesive Modeling Technique Based on the Fracture Mechanics

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3364
Author(s):  
Young Cheol Kim ◽  
Soon Ho Yoon ◽  
Geunsu Joo ◽  
Hong-Kyu Jang ◽  
Ji-Hoon Kim ◽  
...  
Keyword(s):  
Fracture Mechanics ◽  
Composite Laminates ◽  
Cohesive Zone Model ◽  
Failure Behavior ◽  
Zone Model ◽  
Displacement Curve ◽  
Adhesive Failure ◽  
Aluminum Composite ◽  
Explicit Finite Element ◽  
Modeling Techniques

This study describes the numerical simulation results of aluminum/carbon-fiber-reinforced plastic (CFRP) hybrid joint parts using the explicit finite-element solver LS-DYNA, with a focus on capturing the failure behavior of composite laminates as well as the adhesive capacity of the aluminum–composite interface. In this study, two types of adhesive modeling techniques were investigated: a tiebreak contact condition and a cohesive zone model. Adhesive modeling techniques have been adopted as a widely commercialized model of structural adhesives to simulate adhesive failure based on fracture mechanics. CFRP was studied with numerical simulations utilizing LS-DYNA MAT54 to analyze the crash capability of aluminum/CFRP. To evaluate the simulation model, the results were compared with the force–displacement curve from numerical analysis and experimental results. A parametric study was conducted to evaluate the effect of different fracture toughness values used by designers to predict crash capability and adhesive failure of aluminum/CFRP parts.

scholarly journals Fracture Behaviour of Real Coarse Aggregate Distributed Concrete under Uniaxial Compressive Load Based on Cohesive Zone Model

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4314
Author(s):  
Jingwei Ying ◽  
Jin Guo
Keyword(s):  
Finite Element ◽  
Uniaxial Compression ◽  
Digital Image ◽  
Cohesive Zone Model ◽  
Compressive Load ◽  
Strain Ratio ◽  
Image Correlation ◽  
Zone Model ◽  
Cohesive Elements ◽  
Compression Loading

Two-dimensional meso-scale finite element models with real aggregates are developed using images obtained by digital image processing to simulate crack propagation processes in concrete under uniaxial compression loading. The finite element model is regarded as a three-phase composite material composed of aggregate, mortar matrix and interface transition zone (ITZ). Cohesive elements with traction–separation laws are used to simulate complex nonlinear fracture. During the experiment, digital image correlation (DIC) was used to obtain the deformation and cracks of the specimens at different loading stages. The concept of strain ratio is proposed to describe the effectiveness of simulation. Results show that the numerical strain ratio curve and stress–strain curves are both in good agreement with experimental data. The consistency between the cracks obtained by simulation and those obtained by DIC shows the good performance of cohesive elements as well as the effectiveness of simulation. In summary, the model is able to provide accurate predictions of the whole fracture process in concrete under uniaxial compression loading.

scholarly journals Numerical Simulation of Fatigue Crack Growth Rate and Crack Retardation due to an Overload Using a Cohesive Zone Model

2014 ◽  
Vol 891-892 ◽  
pp. 777-783 ◽  
Author(s):  
Sarmediran Silitonga ◽  
Johan Maljaars ◽  
Frans Soetens ◽  
Hubertus H. Snijder
Keyword(s):  
Finite Element ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Crack Tip ◽  
Zone Model ◽  
Cohesive Elements

In this work, a numerical method is pursued based on a cohesive zone model (CZM). The method is aimed at simulating fatigue crack growth as well as crack growth retardation due to an overload. In this cohesive zone model, the degradation of the material strength is represented by a variation of the cohesive traction with respect to separation of the cohesive surfaces. Simulation of crack propagation under cyclic loads is implemented by introducing a damage mechanism into the cohesive zone. Crack propagation is represented in the process zone (cohesive zone in front of crack-tip) by deterioration of the cohesive strength due to damage development in the cohesive element. Damage accumulation during loading is based on the displacements in the cohesive zone. A finite element model of a compact tension (CT) specimen subjected to a constant amplitude loading with an overload is developed. The cohesive elements are placed in front of the crack-tip along a pre-defined crack path. The simulation is performed in the finite element code Abaqus. The cohesive elements behavior is described using the user element subroutine UEL. The new damage evolution function used in this work provides a good agreement between simulation results and experimental data.

Numerical Analysis on the Influence of Interface on the Mechanical Behavior of Unidirectional Fiber Composites under Different Loads

2013 ◽  
Vol 575-576 ◽  
pp. 188-193
Author(s):  
Peng Qu ◽  
Yu Xi Jia ◽  
Guo Wei Zhu ◽  
Yun Li Guo ◽  
Xiao Chen Sun
Keyword(s):  
Mechanical Behavior ◽  
Cohesive Zone Model ◽  
Interfacial Strength ◽  
Unidirectional Composite ◽  
Transverse Load ◽  
Failure Behavior ◽  
Zone Model ◽  
Failure Strength ◽  
Multi Scale ◽  
Representative Unit Cell

On the smallest structural scale in the multi-scale structure composites, namely fiber scale, a numerical model was proposed for the analysis on the mechanical properties of unidirectional composites through the representative unit cell (RUC). The progressive method was used to simulate the failure behavior of fiber and matrix, and the debonding between fiber and matrix was characterized by the cohesive zone model (CZM). The failure strength of the unidirectional composite was predicted, and the influence of the interfacial strength on the mechanical behavior of unidirectional composite was discussed. It is shown that fiber dominates the failure strength of the material under the longitudinal load, whereas under the transverse load interfacial properties play an important role in the mechanical behavior of the material. The increase of the interfacial strength can significantly improve the capability of transverse compression and shear resistance.

Modeling of Cohesive Zone and Crack Growth in Ni-Al Thin-Film Using MD-XFEM Based Approach

2010 ◽  
Author(s):  
Gaurav Singh ◽  
Vijay Kumar Sutrakar ◽  
D. Roy Mahapatra
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Solid Phase ◽  
Md Simulations ◽  
Failure Behavior ◽  
Mode I ◽  
Zone Model ◽  
Al Thin Film

Intermetallic alloys of Ni-Al have important applications in high temperature anti-corrosive coatings, engine and turbine related materials, and shape memory devices. Predicting failure behavior of these materials is difficult using purely continuum model, since several of the material constants are complicated functions of micro and nano-scale details. This includes solid-solid phase transformation. In the present paper, a framework for analyzing fracture in two-dimensional planar domain is developed using a molecular dynamic (MD) simulation and extended finite element method (XFEM). The framework is then applied to simulate fracture in Ni-Al thin-film. Effect of Ni Al crystallites of various sizes on the mechanical properties is analyzed using direct MD simulations. Initiation and growth of crack under slow (quasi-static) tensile loading in mode-I condition is considered. Mechanical properties at room temperature are estimated via MD simulations, which are further used in the XFEM at the continuum scale. A cohesive zone model for the macroscopic XFEM model is implemented, which directly bridges the molecular length-scale via MD framework. Numerical convergence studies are reported for mode-I crack in initially single crystal B2 Ni-Al thin film.

scholarly journals Modelling Microstructural Deformation and the Failure Process of Plastic Bonded Explosives Using the Cohesive Zone Model

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3661 ◽  
Author(s):  
Kaida Dai ◽  
Baodi Lu ◽  
Pengwan Chen ◽  
Jingjing Chen
Keyword(s):  
Mechanical Behavior ◽  
Cohesive Zone ◽  
Shear Failure ◽  
Cohesive Zone Model ◽  
Failure Process ◽  
Interface Debonding ◽  
Zone Model ◽  
Strain Rates ◽  
Cohesive Elements ◽  
Failure Evolution

A microstructure finite element method combining the cohesive zone model (CZM) is used to simulate the mechanical behavior, deformation, and failure of polymer-bonded explosive (PBX) 9501 under quasi-static loading. PBX 9501 consists of Cyclotetramethylene tetranitramine (HMX) filler particles with a random distribution packaged in a polymeric binder. The particle is treated as elastic and the binder as viscoelastic. Cohesive elements with a bilinear softening law are inserted into the particle/binder interface, the HMX particle, and the binder to study the interface’s debonding and failure evolution. Macroscopic stress–strain curves homogenized across the microstructure under tension and compression with different strain rates are basically consistent with the experimental data. The interface debonding approximately vertical to the loading direction is the primary failure mechanism under tension, while shear failure along the interfaces and particle fracture plays a significant role under compression. The effects of interface strengths and strain rates on the performance of PBX 9501 are also evaluated. The tensile and compressive strengths are dependent on the interface strength and strain rate, but the failure paths are insensitive. This model is shown to accurately predict macroscopic responses and improve our understanding of the relationship between the mechanical behavior and microstructure of PBX 9501.

Characterization of Hydrogen-Induced Contact Fracture in High-Strength Steel

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Akio Yonezu ◽  
Michihiro Niwa ◽  
Xi Chen
Keyword(s):  
Crack Propagation ◽  
Hydrogen Content ◽  
High Strength Steel ◽  
Cohesive Zone Model ◽  
High Strength ◽  
Zone Model ◽  
Cracking Behavior ◽  
Stress Criterion ◽  
Contact Fracture ◽  
Fracture Damage

This study investigated the hydrogen embrittlement (HE) cracking behavior produced by local contact loading of high-strength steel. When a spherical impression was applied to a hydrogen-absorbed high-strength steel, HE induces contact fracture, where radial cracks are initiated and propagated from the indentation impression. The length of the radial crack was found to be dependent on the hydrogen content in the steel as well as the applied contact force. A combined experimental/computational investigation was conducted in order to clarify the mechanism of hydrogen-induced contact fracture. In the computation, crack propagation was simulated using a cohesive zone model (CZM) in finite element method (FEM), in order to elucidate stress criterion of the present HE crack. It was found that the normal tensile stress was developed around impression, and it initiated and propagated the HE crack. It was also revealed that the hydrogen content enhanced contact fracture damage, especially the resistance of crack propagation (i.e., threshold stress intensity factor, Kth). The findings may be useful for countermeasure of contact fracture coupled with hydrogen in high-strength steel. Such phenomenon is potentially experienced in various contact components in hydrogen environment.

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