3D modeling of cleavage crack arrest with a stress criterion

2012 ◽  
Vol 90 ◽  
pp. 161-171 ◽  
Author(s):  
C. Berdin
Keyword(s):  
3D Modeling ◽  
Crack Arrest ◽  
Cleavage Crack ◽  
Stress Criterion

3D Modeling of Crack Arrest Experiment With a Local Approach

2009 ◽  
Author(s):  
Anna Dahl ◽  
Dominique Moinereau ◽  
Clotilde Berdin ◽  
Yves Meziere
Keyword(s):  
Thermal Shock ◽  
3D Modeling ◽  
Critical Stress ◽  
Local Stress ◽  
Crack Arrest ◽  
Cleavage Crack ◽  
Local Approach ◽  
Stress Criterion ◽  
Shock Experiment ◽  
Front Shape

A local stress criterion based on the maximal principal stress is applied for 3D-modeling crack arrest experiments: thermal shock experiments on precracked disc. The crack front shape is simulated and compared to the experimental results. A scatter in critical stress for cleavage crack arrest is introduced through Monte-Carlo simulations with the Weibull distribution. As a result, for the thermal shock experiment on precracked disc, the scatter in critical stress has no influence on the crack length at arrest, but the regularity of the simulated crack arrest front depends on it. This result can be due to the mechanical aspect of the test rather than to the micro-mechanisms of cleavage crack arrest: the vibration of the disc induces the crack closure.

Cleavage Crack Propagation and Arrest Prediction in French PWR Vessel Steel

2014 ◽  
Author(s):  
Xiaoyu Yang ◽  
Stéphane Marie ◽  
Philippe Bompard ◽  
Clémentine Jacquemoud
Keyword(s):  
Mixed Mode ◽  
Crack Arrest ◽  
Pressure Vessels ◽  
Plastic Strain Rate ◽  
Cleavage Crack ◽  
Mixed Mode Loading ◽  
Vessel Steel ◽  
Stress Criterion ◽  
Different Temperatures ◽  
Crack Paths

The integrity assessment of Reactor Pressure Vessels is mainly based on crack initiation. Nevertheless, in the frame of component life extension, crack arrest conception is investigated. This paper presents a local non-linear dynamic model to predict the propagation and arrest of cleavage crack in French PWR vessel steel (16MND5). The propagation criterion used in this model is a Ritchie Knott and Rice (RKR) fracture stress criterion: the crack propagates when the maximum stress ahead of crack tip reaches a critical level, which has been shown to depend on temperature and plastic strain rate. In the first step, the criterion has been identified from crack growth and arrest analysis on CT specimens at different temperatures. Then it was applied to predict the propagation and arrest of cleavage cracks on pre-cracked rings under mixed mode loading, at three different temperatures: −150°C, −125°C and −100°C. 2D modeling was performed by using extended element method (XFEM) in CAST3M software. The propagation direction on pre-crack rings under mixed mode loading was determined from maximum hoop stress criterion. Numerical computation showed a good agreement with experiments, for both curved crack paths and crack arrest locations. Furthermore it showed that crack paths and crack arrest also depend on the level of the crack loading at initiation.

Analyses of cleavage crack arrest experiments: influence of specimen vibration

2008 ◽  
Vol 75 (5) ◽  
pp. 1156-1170 ◽  
Author(s):  
M. Hajjaj ◽  
C. Berdin ◽  
P. Bompard ◽  
S. Bugat
Keyword(s):  
Crack Arrest ◽  
Cleavage Crack

Cleavage Crack Path Prediction in a PWR Vessel Steel

2014 ◽  
Author(s):  
Xiaoyu Yang ◽  
Stéphane Marie ◽  
Clémentine Jacquemoud
Keyword(s):  
Crack Propagation ◽  
Crack Path ◽  
Cleavage Crack ◽  
Extended Finite Element ◽  
Vessel Steel ◽  
Stress Criterion ◽  
Statistical Effect ◽  
Path Prediction ◽  
Crack Paths ◽  
Crack Path Prediction

Cleavage crack propagation has been tested for three different geometries of Compact Tensile (CT) specimens: CT25, CT50 and extended CT25 (CT25 with CT50 width) (Figure 3). The experimental results show that the crack paths are straight for CT25 and CT50, but they are unstable and curved for extended CT specimens (Figure 5 to 7). Numerical computation had been performed by extended finite element method (XFEM) in CAST3M software. 2D modeling was used in order to predict the crack path. The analysis was based on a local non-linear dynamic approach with a RKR fracture stress criterion depending on temperature and strain rate. In order to simulate the curvature of the cracks path, a statistical effect was introduced in the model to take into account the spatial distribution of cleavage initiators, which is the characteristic of cleavage fracture. At each step of propagation during the modeling, the direction was randomly chosen, according to a uniform defects distribution. The numerical results show a good agreement with experience. The different crack paths were curved in extended CT25, but remained almost straight in CT25 and CT50 specimens, despite of the instability introduced in the modeling in the propagation direction. These results show that the statistics of micro-defects can induce, jointly with the geometry of specimen, a large scatter of crack propagation paths.

The Interrelationships of KIa, KIc, and JIc, and the Implications of These Relationships on Use of Fracture Models Over the Ranges of Hardening Observed in Ferritic Steels

2006 ◽  
Author(s):  
Marjorie EricksonKirk ◽  
Mark EricksonKirk ◽  
Tim Williams
Keyword(s):  
Fracture Toughness ◽  
Crack Initiation ◽  
Master Curve ◽  
Crack Arrest ◽  
Nuclear Industry ◽  
Ferritic Steels ◽  
Initiation Toughness ◽  
Cleavage Crack ◽  
The Mean ◽  
Arrest Toughness

Models to predict the fracture and arrest behavior of ferritic steels, particularly those in use in the nuclear industry, have long been under development. The current, most widely accepted model of fracture toughness behavior is the ASTM E1921-02 “Master Curve” that is used to predict the variation of the mean cleavage fracture toughness with temperature in the transition temperature region as well as predicting the scatter of data about the mean at any given temperature. Recently, models describing the variation of arrest fracture toughness and of ductile initiation toughness with temperature have also been proposed. A study has been conducted with the goal of assessing how the scatter in cleavage initiation toughness may vary with temperature and level of irradiation embrittlement, which utilizes the crack arrest and ductile crack initiation models to redefine limits of applicability of the Master Curve-assumed Weibull distribution by developing empirically-derived interrelationships between the three models. These relationships are expected as all three parameters, KIc, KIa, and JIc, are controlled by the flow behavior of the material. There is a physical basis for viewing the crack arrest toughness as an absolute lower bound to the distribution of crack initiation toughness values for a fixed material condition and temperature. This physically based relationship, borne of the fact that both cleavage crack initiation toughness and cleavage crack arrest toughness are controlled by dislocation mobility, has brought about the suggestion that crack arrest toughness could be used to modify the lower tails of the crack initiation fracture toughness distribution. Using both empirical evidence and a hardening model proposed by Natishan and Wagenhofer, we investigate the relationship between initiation and arrest toughness and the implications on use of toughness models.

Local approach to fracture for cleavage crack arrest prediction

2008 ◽  
Vol 75 (11) ◽  
pp. 3264-3275 ◽  
Author(s):  
Clotilde Berdin ◽  
Mejido Hajjaj ◽  
Philippe Bompard ◽  
Stéphane Bugat
Keyword(s):  
Crack Arrest ◽  
Cleavage Crack ◽  
Local Approach

Use of a Unified Model for the Fracture Toughness of Ferritic Steels in the Transition and on the Upper Shelf in Fitness-for-Service Assessment and in the Design of Fracture Toughness Experiments

2006 ◽  
Author(s):  
Mark T. EricksonKirk ◽  
MarjorieAnn EricksonKirk
Keyword(s):  
Fracture Toughness ◽  
Research Work ◽  
Crack Arrest ◽  
Algebraic Expression ◽  
Ferritic Steels ◽  
Cleavage Crack ◽  
Combined Model ◽  
Toughness Index ◽  
Potential Applications ◽  
Initiation Fracture Toughness

Models to predict the fracture and arrest behavior of ferritic steels have long been under development. The current, most widely accepted model of fracture toughness behavior is the ASTM E1921-02 “Master Curve” that is used to predict the variation of the median cleavage fracture toughness (KJc) with temperature in the transition temperature region, as well as predicting the scatter of data about the median at any given temperature. Recently, models describing the variation of crack arrest fracture toughness (KIa) and of ductile initiation fracture toughness (JIc) with temperature have also been proposed. Moreover, models are also available that relate these various temperature dependencies to each other, and relate them all a common parameter, the cleavage crack initiation fracture toughness index temperature To. Research work continues to better quantify these relationships and to more firmly understand their physical bases. Nevertheless, the ample empirical evidence on which the models are based and the existing physical understanding underlying the models suggests that they can be used as a tool in both fitness-for-service assessment and in the design of experiments conducted to investigate the fracture toughness of ferritic materials. While still being developed, these toughness-based models offer clear advantages relative to alternative (correlative) approaches in terms of reduced prediction uncertainty. In this paper we amalgamate the results of previous publications to provide an algebraic expression for the variation of KJc, KIa, and JIc with temperature that includes explicit quantification of the uncertainty in each variable. We also discuss the implications and potential applications of this combined model.

scholarly journals Finite Element Simulation of a Crack Growth in the Presence of a Hole in the Vicinity of the Crack Trajectory

Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 363
Author(s):  
Abdulnaser M. Alshoaibi ◽  
Yahya Ali Fageehi
Keyword(s):  
Crack Growth ◽  
Crack Path ◽  
Circumferential Stress ◽  
Crack Arrest ◽  
Growth Direction ◽  
Stress Criterion ◽  
Crack Trajectory ◽  
Linear Elastic ◽  
New Feature ◽  
Crack Growth Path

The aim of this paper was to present a numerical simulation of a crack growth path and associated stress intensity factors (SIFs) for linear elastic material. The influence of the holes’ position and pre-crack locations in the crack growth direction were investigated. For this purpose, ANSYS Mechanical R19.2 was introduced with the use of a new feature known as Separating Morphing and Adaptive Remeshing Technology (SMART) dependent on the Unstructured Mesh Method (UMM), which can reduce the meshing time from up to several days to a few minutes, eliminating long preprocessing sessions. The presence of a hole near a propagating crack causes a deviation in the crack path. If the hole is close enough to the crack path, the crack may stop at the edge of the hole, resulting in crack arrest. The present study was carried out for two geometries, namely a cracked plate with four holes and a plate with a circular hole, and an edge crack with different pre-crack locations. Under linear elastic fracture mechanics (LEFM), the maximum circumferential stress criterion is applied as a direction criterion. Depending on the position of the hole, the results reveal that the crack propagates in the direction of the hole due to the uneven stresses at the crack tip, which are consequences of the hole’s influence. The results of this modeling are validated in terms of crack growth trajectories and SIFs by several crack growth studies reported in the literature that show trustworthy results.

A Model Is Worth 1,000 Pictures: Applications of 3D-Modeling in Skull Base Surgery Neuroanatomy Education

2020 ◽  
Author(s):  
Christopher S. Graffeo ◽  
Avital Perry ◽  
Lucas P. Carlstrom ◽  
Michael J. Link ◽  
Jonathan Morris
Keyword(s):  
Skull Base ◽  
3D Modeling ◽  
Skull Base Surgery

3D modeling of the vascular system

2016 ◽  
Vol 1 (1) ◽  
pp. 51-58 ◽  
Author(s):  
Jean François Uhl ◽  
Maxime Chahim ◽  
François Cros ◽  
Amina Ouchene ◽  
◽  
...  
Keyword(s):  
Augmented Reality ◽  
3D Modeling ◽  
Vascular System ◽  
Arterial System ◽  
Chronic Venous Disease ◽  
Venous Disease ◽  
Software Products ◽  
Operative Planning ◽  
Morphological Modeling ◽  
Pre Treatment

The 3D modeling of the vascular system could be achieved in different ways: In the venous location, the morphological modeling by MSCT venography is used to image the venous system: this morphological modeling tool accurately investigates the 3D morphology of the venous network of our patients with chronic venous disease. It is also a fine educational tool for students who learn venous anatomy, the most complex of the human body. Another kind of modeling (mathematical modeling) is used to simulate the venous functions, and virtually tests the efficacy of any proposed treatments. To image the arterial system, the aim of 3D modeling is to precisely assess and quantify the arterial morphology. The use of augmented reality before an endovascular procedure allows pre-treatment simulation, assisting in pre-operative planning as well as surgical training. In the special field of liver surgery, several 3D modeling software products are available for computer simulations and training purposes and augmented reality.

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