Modeling and Simulation of Crack Initiation and Growth in Particulate Composites

1997 ◽  
Vol 119 (3) ◽  
pp. 319-324 ◽  
Author(s):  
Y. W. Kwon ◽  
J. H. Lee ◽  
C. T. Liu
Keyword(s):  
Crack Initiation ◽  
Modeling And Simulation ◽  
Composite Structures ◽  
Damage Mechanics ◽  
Damage Zone ◽  
Micromechanical Model ◽  
Particulate Composite ◽  
Computational Effort ◽  
Particulate Composites ◽  
Initiation And Propagation

A micro/macromechanical approach was used to model and simulate crack initiation and crack propagation in particulate composite structures. The approach used both the micromechanical and macromechanical analyses in tandem. The micromechanical analysis was based on a simplified micromechanical model and damage mechanics at the micro-level, and the macromechanical analysis utilized the finite element method. In using these methods, crack initiation and growth in a general shape of composite structure were investigated with an efficient computational effort. It was assumed that a crack initiates and/or propagates when localized damage is saturated. As a result, the crack length was assumed to be the size of the saturated damage zone. Matrix crack initiation and propagation at circular notch tips were simulated using this approach. Modeling and simulation were also conducted for cases of nonuniform particle distribution in particulate composite structures. Predicted results showed a good agreement with the experimental data.

Crack Initiation and Growth in Bimetallic Girth Welds

2014 ◽  
Author(s):  
Antonio Carlucci ◽  
Nicola Bonora ◽  
Andrew Ruggiero ◽  
Gianluca Iannitti ◽  
Domenico Gentile
Keyword(s):  
Crack Initiation ◽  
Damage Mechanics ◽  
Damage Model ◽  
Mouth Opening ◽  
Crack Mouth Opening Displacement ◽  
Model Parameters ◽  
Ductile Crack ◽  
Crack Initiation And Propagation ◽  
Initiation And Propagation ◽  
Girth Welds

Bimetallic girth welds are characteristics of clad pipe technology. When dealing with propagation issues, fracture mechanics concepts usually are no longer applicable as a result of the extensive and non-homogeneous plastic deformation along bi-material interface that occur at the crack tip even below design allowables. In this study, ductile crack initiation and propagation in bi-material girth welds was investigated using a Continuum Damage Mechanics (CDM) model proposed by Bonora [1]. For the base, weld and clad metal, ductile damage model parameters have been determined by means of inverse calibration technique using fracture data obtained on smooth and round notched tensile bar specimens. Firstly, the damage model was validated predicting ductile crack growth occurring in single end notch (SEN(T)) geometry sample comparing the applied load vs crack mouth opening displacement with experimental measurements. Successively, the model was used to investigate ductile crack initiation and propagation for under clad circumferential weld crack under remote tension.

scholarly journals Simulation of Crack Initiation and Propagation in the Crystals of a Beam Blank

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 905 ◽  
Author(s):  
Gaiyan Yang ◽  
Liguang Zhu ◽  
Wei Chen ◽  
Gaoxiang Guo ◽  
Baomin He
Keyword(s):  
Crack Initiation ◽  
Tensile Stress ◽  
Damage Mechanics ◽  
Stress And Strain ◽  
Crack Initiation And Propagation ◽  
Surface Cracking ◽  
Initiation And Propagation ◽  
Polycrystalline Model ◽  
Abaqus Software

Surface cracking seriously affects the quality of beam blanks in continuous casting. To study the mechanism of surface crack initiation and propagation under beam blank mesoscopic condition, this study established a polycrystalline model using MATLAB. Based on mesoscopic damage mechanics, a full implicit stress iterative algorithm was used to simulate the crack propagation and the stress and strain of pores and inclusions of the polycrystalline model using ABAQUS software. The results show that the stress at the crystal boundary is much higher than that in the crystal, cracks occur earlier in the former than in the latter, and cracks extend along the direction perpendicular to the force. When a polycrystalline model with pores is subjected to tensile stress, a stress concentration occurs when the end of the pores is perpendicular to the stress direction, and the propagation and aggregation direction of the pores is basically perpendicular to the direction of the tensile stress. When a polycrystalline model with impurities is subjected to force, the stress concentrates around the impurity but the strain here is minimal, which leads to the crack propagating along the impurity direction. This study can provide theoretical guidance for controlling the generation of macroscopic cracks in beam blanks.

Micromechanical Modeling of Crack Initiation and Propagation in the Ductile-Brittle Transition Region

2016 ◽  
Vol 713 ◽  
pp. 58-61
Author(s):  
Giang Ngoc Anh ◽  
Geralf Hütter ◽  
Meinhard Kuna
Keyword(s):  
Crack Initiation ◽  
Transition Region ◽  
Process Zone ◽  
Micromechanical Model ◽  
Metallic Matrix ◽  
Micromechanical Modeling ◽  
Crack Initiation And Propagation ◽  
Brittle Transition ◽  
Complex Interactions ◽  
Initiation And Propagation

In the present study the crack initiation and propagation is investigated in the ductile-brittle transition region by means of a microscopic model. In particular, the particles in the process zone in front of the crack tip are resolved discretely in finite element simulations. The competing mechanisms of particle debonding and possible subsequent void growth as well as particle breakage and cleavage of the metallic matrix are incorporated explicitly in the micromechanical model by means of a cohesive zone. This approach accounts for the complex interactions of the mechanisms and allows to simulate all stages of crack initiation and propagation at all relevant temperatures.

Creep Crack Initiation and Propagation: Fracture Mechanics and Local Approach

1988 ◽  
Vol 110 (1) ◽  
pp. 42-50 ◽  
Author(s):  
P. Bensussan ◽  
E. Maas ◽  
R. Pelloux ◽  
A. Pineau
Keyword(s):  
Fracture Mechanics ◽  
Crack Initiation ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Crack Initiation And Propagation ◽  
Local Approach ◽  
Element Analysis ◽  
Creep Ductility ◽  
Creep Crack ◽  
Initiation And Propagation

Both the initiation and the propagation of macroscopic creep cracks have been studied in 316-L austenitic stainless steel, and, for comparison purposes, in 2219-T851 aluminum alloy. These alloys are, respectively, creep-ductile and creep-brittle. This difference in behavior is explained in terms of fracture mechanics concepts applied to creeping solids. The inability of fracture mechanics in providing unique correlations with K, C*, etc. . . for all the stages of both creep crack initiation and propagation is pointed out. Life prediction schemes using local rather than global fracture criteria are presented. A model based on creep ductility exhaustion concepts and the stress fields obtained by fracture mechanics is shown to provide good predictions for 316-L. Finite element analysis coupled to continuum damage mechanics is found to describe creep crack initiation in 2219-T851.

Crack Initiation and Propagation Clad Pipe Girth Weld Flaws

2014 ◽  
Author(s):  
Antonio Carlucci ◽  
Nicola Bonora ◽  
Andrew Ruggiero ◽  
Gianluca Iannitti ◽  
Gabriel Testa
Keyword(s):  
Crack Initiation ◽  
Large Scale ◽  
Damage Mechanics ◽  
High Fracture Toughness ◽  
Model Parameters ◽  
Equivalent Material ◽  
Ductile Crack ◽  
Crack Initiation And Propagation ◽  
Brittle Ductile Transition ◽  
Initiation And Propagation

At present, design standards and prescriptions do not provide specific design routes to perform engineering criticality assessment (ECA) of bimetallic girth welds. Although the authors has shown the possibility to implement ECA in accordance with available prescriptions of such flawed weld joint following the equivalent material method (EMM), when dealing with ductile crack initiation and propagation — as a result of the large scale yielding occurring at the crack tip for high fracture toughness material operating in the brittle-ductile transition region — fracture mechanics concepts such as JIc or critical CTOD may breakdown. In this work, the possibility to accurately determine the condition for ductile crack growth initiation and propagation in bi-metallic girth weld flaws using continuum damage mechanics is shown. Here, the base metal as well as the clad and the weld metal have been characterized to determine damage model parameters. Successively, the geometry transferability of model parameters has been validated. Finally, the model has been used to predict crack initiation for two bi-material interface circumferential crack configurations.

scholarly journals Low-Cycle Fatigue Crack Initiation Simulation and Life Prediction of Powder Superalloy Considering Inclusion-Matrix Interface Debonding

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4018
Author(s):  
Shuming Zhang ◽  
Yuanming Xu ◽  
Hao Fu ◽  
Yaowei Wen ◽  
Yibing Wang ◽  
...  
Keyword(s):  
Finite Element ◽  
Crack Initiation ◽  
Life Prediction ◽  
Damage Mechanics ◽  
Low Cycle Fatigue ◽  
Fatigue Crack Initiation ◽  
Fatigue Loading ◽  
Interface Debonding ◽  
Damage Evolution Equation ◽  
Finite Element Software

From the perspective of damage mechanics, the damage parameters were introduced as the characterizing quantity of the decrease in the mechanical properties of powder superalloy material FGH96 under fatigue loading. By deriving a damage evolution equation, a fatigue life prediction model of powder superalloy containing inclusions was constructed based on damage mechanics. The specimens containing elliptical subsurface inclusions and semielliptical surface inclusions were considered. The CONTA172 and TARGE169 elements of finite element software (ANSYS) were used to simulate the interfacial debonding between the inclusions and matrix, and the interface crack initiation life was calculated. Through finite element modeling, the stress field evolution during the interface debonding was traced by simulation. Finally, the effect of the position and shape size of inclusions on interface debonding was explored.

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