CREEP FRACTURE MODELING BY CONTINUUM DAMAGE VARIABLE BASED ON VORONOI SIMULATION OF GRAIN BOUNDARY CAVITY

1996 ◽  
pp. 285-290
Author(s):  
Yan LIU ◽  
Yoshihiro KAGEYAMA ◽  
Sumio MURAKAMI
Keyword(s):  
Grain Boundary ◽  
Damage Variable ◽  
Continuum Damage ◽  
Creep Fracture ◽  
Fracture Modeling

Mechanics of damage, healing, damageability, and integrity of materials: A conceptual framework

2016 ◽  
Vol 26 (1) ◽  
pp. 50-103 ◽  
Author(s):  
George Z Voyiadjis ◽  
Peter I Kattan
Keyword(s):  
Damage Mechanics ◽  
Healing Process ◽  
Continuum Damage Mechanics ◽  
Damage Variable ◽  
Continuum Damage ◽  
Variable Section ◽  
Damage Healing ◽  
Characterization Of Materials ◽  
New Formulation

In this work several new and fundamental concepts are proposed within the framework of continuum damage mechanics. These concepts deal primarily with the nature of the two processes of damage and healing along with introducing a consistent and systematic definition for the concepts of damageability and integrity of materials. Toward this end, seven sections are presented as follows: “The logarithmic damage variable” section introduces the logarithmic and exponential damage variables and makes comparisons with the classical damage variable. In “Integrity and damageability of materials” section a new formulation for damage mechanics is presented in which the two angles of damage–integrity and healing–damageability are introduced. It is shown that both the damage variable and the integrity variable can be derived from the damage–integrity angle while the healing variable and damageability variable are derived from the healing–damageability angle. “The integrity field” section introduces the new concept of the integrity field while “The healing field” section introduces the new concept of the healing field. These two fields are introduced as a generalization of the classical concepts of damage and integrity. “Unhealable damage and nondamageable integrity” section introduces the new and necessary concept of unrecoverable damage or unhealable damage. In this section the concept of permanent integrity or nondamageable integrity is also presented. In “Generalized nonlinear healing” section generalized healing is presented where a distinction is clearly made between linear healing and nonlinear healing. As an example of nonlinear healing the equations of quadratic healing are derived. Finally in “Dissection of the healing process” section a complete and logical/mathematical dissection is made of the healing process. It is hoped that these new and fundamental concepts will pave the way for new, consistent, and holistic avenues in research in damage mechanics and characterization of materials.

GROWTH AND LINKAGE OF CRACKS AND FORMATION OF CREEP FRACTURE PATTERN SIMULATED BY A MULTICRACK GROWTH MODEL

Fractals ◽  
2001 ◽  
Vol 09 (02) ◽  
pp. 223-230 ◽  
Author(s):  
MANABU TANAKA ◽  
RYUICHI KATO ◽  
ATSUSHI KAYAMA
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Growth Model ◽  
Size Dependence ◽  
Grain Boundary Sliding ◽  
Fracture Pattern ◽  
Square Lattice ◽  
Creep Fracture ◽  
Lattice Effects ◽  
Boundary Sliding

A computer simulation using a multicrack growth model was carried out on the growth and linkage of cracks and the formation of creep fracture pattern resulting from the initial defects. The percolated crack patterns and the number of steps to percolation were examined by Monte Carlo simulation on a square lattice. Effects of stress and grain size on creep fracture process are then discussed. The stress and grain size dependence of the number of steps to percolation in the simulation was similar to that of grain-boundary sliding in the austenitic 21Cr-4Ni-9Mn heat-resisting steel, which controlled the growth of grain-boundary cracks. The fractal dimension of the percolation crack was also correlated with that of the creep fracture pattern in the 21Cr-4Ni-9Mn steel.

DEPENDENCE OF CREEP FRACTURE OF INCONEL 718 ON GRAIN BOUNDARY PRECIPITATES

1997 ◽  
Vol 45 (7) ◽  
pp. 2735-2746 ◽  
Author(s):  
W. CHEN ◽  
M.C. CHATURVEDI
Keyword(s):  
Grain Boundary ◽  
Inconel 718 ◽  
Creep Fracture

Effects of grain boundary heterogeneities on creep fracture studied by rate-dependent cohesive model

2012 ◽  
Vol 93 ◽  
pp. 48-64 ◽  
Author(s):  
Chi-Hua Yu ◽  
Chang-Wei Huang ◽  
Chuin-Shan Chen ◽  
Yanfei Gao ◽  
Chun-Hway Hsueh
Keyword(s):  
Grain Boundary ◽  
Cohesive Model ◽  
Creep Fracture ◽  
Rate Dependent

scholarly journals On certain fundamental issues in continuum damage mechanics

2012 ◽  
Vol 21 (1-2) ◽  
pp. 33-36
Author(s):  
George Z. Voyiadjis ◽  
Peter I. Kattan
Keyword(s):  
Deformation Process ◽  
Damage Mechanics ◽  
Materials Science ◽  
Continuum Damage Mechanics ◽  
Damage Variable ◽  
Continuum Damage ◽  
Secondary Damage ◽  
Damage Process ◽  
Primary Damage ◽  
Definition Of

AbstractIn this article, we discuss three fundamental issues in continuum damage mechanics. First, we investigate the nature of the damage process. For this purpose, we dissect the expression of the effective stress into an infinite geometric series and introduce several stages of damage that we call primary damage, secondary damage, tertiary damage, etc. The second issue to be discussed is the problem of small damage. In this regard, we introduce a new definition of the damage variable that is suitable for small-damage cases. Finally, we discuss the new concept of undamageable materials. These are currently hypothetical materials that maintain a zero value of the damage variable throughout the deformation process. It is hoped that these proposed new types of materials will open the way to new areas of research in both damage mechanics and materials science.

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