Evaluating Fracture Toughness of Ductile Materials: A Critical Indentation Energy Model Based on Continuum Damage Mechanics

2005 ◽  
Author(s):  
Jung-Suk Lee ◽  
Eui-Hyun Kim ◽  
Dongil Kwon
Keyword(s):  
Fracture Toughness ◽  
Damage Mechanics ◽  
Volume Fraction ◽  
Continuum Damage Mechanics ◽  
Fracture Toughness Test ◽  
Continuum Damage ◽  
Test Results ◽  
Ductile Materials ◽  
Good Agreement ◽  
Critical Void

A new model for determining fracture toughness of ductile materials is presented that uses indentation and is based on continuum damage mechanics (CDM) and the concept of critical void volume fraction. Fracture toughness evaluated using the model showed good agreement with standard fracture toughness test results.

Nondestructive Estimation of Fracture Toughness Using Instrumented Indentation Technique

2008 ◽  
Vol 385-387 ◽  
pp. 893-896
Author(s):  
Kyung Woo Lee ◽  
Hyun Uk Kim ◽  
Sang Wook Park ◽  
Jung Suk Lee ◽  
Kwang Ho Kim ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Damage Mechanics ◽  
Volume Fraction ◽  
Fracture Initiation ◽  
Continuum Damage Mechanics ◽  
Instrumented Indentation ◽  
Initiation Point ◽  
Indentation Technique ◽  
Proposed Model ◽  
Main Ideas

This study focused on the determination of fracture toughness by instrumented indentation technique. A theoretical model to estimate the fracture toughness of ductile materials is proposed and used to verify those results. Modeling of IIT to evaluate fracture toughness is based on two main ideas; the energy input up to characteristic fracture initiation point during indentation was correlated with material’s resistance to crack initiation and growth, and this characteristic fracture initiation point was determined by concepts of continuum damage mechanics. The estimated fracture toughness values obtained from the indentation technique showed good agreement with those from conventional fracture toughness tests based on CTOD. In addition, we confirmed that the proposed model can be also applied in the brittle material through modification of void volume fraction.

scholarly journals On continuum damage mechanics

2019 ◽  
Vol 52 (3) ◽  
pp. 125-147
Author(s):  
Kari Juhani Santaoja
Keyword(s):  
Stress Tensor ◽  
Effective Stress ◽  
Elastic Strain ◽  
Damage Mechanics ◽  
Volume Fraction ◽  
Strain Tensor ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
The Matrix ◽  
Elastic Strain Tensor

A material containing spherical microvoids with a Hookean matrix response was shown to take the appearance usually applied in continuum damage mechanics. However, the commonly used variable damage D was replaced with the void volume fraction f , which has a clear physical meaning, and the elastic strain tensor \Bold {ε}^e with the damage-elastic strain tensor \Bold {ε}^{de}. The postulate of strain equivalence with the effective stress concept was reformulated and applied to a case where the response of the matrix obeys Hooke’s law. In contrast to many other studies, in the derived relation between the effective stress tensor \Bold {\Tilde{σ}} and the stress tensor \Bold {σ}, the tensor \Bold {\Tilde{σ}} is symmetric. A uniaxial bar model was introduce for clarifying the derived results. Other candidates for damage were demonstrated by studying the effect of carbide coarsening on creep rate.

scholarly journals A description of crevasse formation using continuum damage mechanics

2003 ◽  
Vol 37 ◽  
pp. 77-82 ◽  
Author(s):  
Antoine Pralong ◽  
Martin Funk ◽  
Martin P. Lüthi
Keyword(s):  
Level Set Method ◽  
Level Set ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Interface Motion ◽  
Glacier Surface ◽  
Polycrystalline Ice ◽  
Isotropic Damage ◽  
Good Agreement

AbstractContinuum damage mechanics describes the progressive deterioration of material subjected to loading. Jointly used with a level-set method, it proves to be a promising approach to computing the interface motion of a damaged material. For polycrystalline ice, a local isotropic damage evolution law (generalized Kachanow’s law) applied to Glen’s flow law allows the description of tertiary creep and facilitates the modeling of crevasse opening using a failure criterion based on damage accumulation. The use of a level-set method permits the description, in a continuum approach, of the motion of a fractured glacier surface. Using these methods, a model is developed. The ability of this model to describe phenomena connected to crevasse opening is presented. The rupture of a large ice block from a hanging glacier is computed and analyzed. The regular acceleration of such an unstable ice block prior to its collapse is calculated and compared to the acceleration function obtained from observations. A good agreement between the two acceleration functions was found.

Radiation Induced Damage in Ductile Materials Subjected to Time-Dependent Stresses

2015 ◽  
Vol 784 ◽  
pp. 43-50 ◽  
Author(s):  
Błażej Skoczeń ◽  
Aneta Ustrzycka
Keyword(s):  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Axial Loads ◽  
Mechanical Loads ◽  
Ductile Materials ◽  
Common Framework ◽  
Radiation Induced ◽  
The Common ◽  
Kinetics Of

The problem undertaken in the present work concerns the kinetics of evolution of radiation induced damage under mechanical loads. Furthermore, coupling between the radiation induced nanodamage and the mechanically induced micro-damage is taken into account. The evolution of radiation induced damage is combined with the evolution of classical mechanically induced damage within the common framework of Continuum Damage Mechanics (CDM). Closed form analytical solutions for the problem of periodic irradiation combined with cyclic axial loads, corresponding to Rice & Tracey law was obtained.

Evaluation of the Effects of Inclusion Distribution on the Local Ductility of DP Steel

2012 ◽  
Vol 706-709 ◽  
pp. 1527-1532 ◽  
Author(s):  
Y. Suwa ◽  
T. Matsuno ◽  
S. Hirose ◽  
N. Fujita ◽  
A. Seto
Keyword(s):  
Finite Element ◽  
Damage Mechanics ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Element Analysis ◽  
Dp Steel ◽  
The Difference ◽  
Inclusion Distribution

In the present study, the effects of inclusions on the local ductility of DP steel are investigated using finite element analysis (FEA). In order to evaluate local ductility, a continuum damage mechanics (CDM) model has been incorporated into the Abaqus/Explicit® commercial finite element code. Furthermore, three-dimensional representative volume elements (RVEs) with ferrite, martensite, and inclusion phases have been used to evaluate the stress-strain response. Simulation results show that the volume fraction of the martensite as well as the difference in hardness between the ferrite and the martensite phases dominates the effect of inclusions on local ductility.

A precipitate evolution-based continuum damage mechanics model of creep behaviour in welded 9Cr steel at high temperature

2018 ◽  
Vol 233 (1) ◽  
pp. 39-51
Author(s):  
C Ó Murchú ◽  
SB Leen ◽  
PE O’Donoghue ◽  
RA Barrett
Keyword(s):  
Damage Mechanics ◽  
Volume Fraction ◽  
Creep Behaviour ◽  
Continuum Damage Mechanics ◽  
Time To Failure ◽  
Continuum Damage ◽  
State Variable ◽  
9Cr Steel ◽  
Mechanics Model ◽  
Physically Based

A multiaxial, physically based, continuum damage mechanics methodology for creep of welded 9Cr steels is presented, incorporating a multiple precipitate-type state variable, which simulates the effects of strain- and temperature-induced coarsening kinematics. Precipitate volume fraction and initial diameter for carbide and carbo-nitride precipitate types are key microstructural variables controlling time to failure in the model. The heat-affected zone material is simulated explicitly utilising measured microstructural data, allowing detailed investigation of failure mechanisms. Failure is shown to be controlled by a combination of microstructural degradation and Kachanov-type damage for the formation and growth of creep cavities. Comparisons with experimental data demonstrate the accuracy of this model for P91 material.

Evaluation of Fracture Toughness for Power Plant Materials Using Continuous Indentation Technique

2006 ◽  
Vol 321-323 ◽  
pp. 480-485 ◽  
Author(s):  
Jung Suk Lee ◽  
Jae Il Jang ◽  
Keun Bong Yoo ◽  
Dong Il Kwon
Keyword(s):  
Fracture Toughness ◽  
Power Plant ◽  
Fracture Toughness Test ◽  
Test Results ◽  
Indentation Fracture ◽  
Current Standard ◽  
Plant Materials ◽  
Indentation Fracture Toughness ◽  
Continuous Indentation ◽  
Good Agreement

An indentation fracture toughness model is applied to estimate non-destructively the fracture toughness of power plant materials such as ASTM A53 and ASME SA335 P91. Fracture toughness evaluated using the model showed good agreement with current standard fracture toughness test results.

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