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 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 When dealing with propagation issues, fracture mechanics concepts usually are no longer applicable as a result of the extensive and non-homogeneous plastic deformation along bi-material interface that occur at the crack tip even below design allowables.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.

Crack Initiation and Propagation as Part of Engineering Design

2012 ◽  
Author(s):  
Hans Minnebo ◽  
Marc Duflot ◽  
Eric Wyart
Keyword(s):  
Fatigue Crack ◽  
Fracture Mechanics ◽  
Crack Initiation ◽  
Crack Initiation And Propagation ◽  
Linear Elastic ◽  
Linear Fracture ◽  
Initiation And Propagation ◽  
Improve Analysis ◽  
Elastic Fracture ◽  
Analysis Design

This article deals with the interest of the analysis of cracks in order to improve analysis design. Mainly oriented around the linear elastic fracture mechanics and fatigue crack propagation, it will also address some issues in non-linear fracture mechanics and crack insertion.

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.

scholarly journals ANALYSIS OF CRACK INITIATION AND PROPAGATION IN PIEZOELECTRIC CERAMIC BY USING BOUNDARY ELEMENT METHOD

2017 ◽  
Vol 23 (4) ◽  
pp. 330
Author(s):  
Feliks Stachowicz ◽  
Mojtaba Biglar ◽  
Magdalena Gromada ◽  
Tomasz Trzepiecinski
Keyword(s):  
Boundary Element Method ◽  
Barium Titanate ◽  
Crack Initiation ◽  
Boundary Element ◽  
Programming Algorithm ◽  
Crack Initiation And Propagation ◽  
Element Analysis ◽  
Barium Titanate Ceramic ◽  
Initiation And Propagation ◽  
Element Method

<p> <strong><span style="font-family: Times New Roman; font-size: small;">Abstract </span></strong></p><p><span style="font-family: Times New Roman;">The subject of this paper is the analysis of crack initiation and propagation in barium titanate ceramic using boundary element method. In micro-mechanical analyses, it is very important to have knowledge about the real microstructure of material. The barium titanate pellet was prepared  using a solid-state technique. The boundary element method is used in order to be combined with three different grain boundary formulations for the investigation of micro-mechanics as well as crack initiation and propagation in piezoelectric actuator. In order to develop a numerical programming algorithm, suitable models of polycrystalline aggregate and representative volume elements have been prepared for boundary element analysis. </span></p>

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