Prediction of Plane-Strain Creep-Crack Growth Using Continuum Damage Mechanics

1996 ◽  
Vol 5 (4) ◽  
pp. 353-383 ◽  
Author(s):  
F. R. Hall ◽  
D. R. Hayhurst ◽  
P. R. Brown
Keyword(s):  
Crack Growth ◽  
Plane Strain ◽  
Damage Mechanics ◽  
Creep Crack Growth ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Creep Crack

The role of continuum damage in creep crack growth

1984 ◽  
Vol 311 (1516) ◽  
pp. 131-158 ◽  
Keyword(s):  
Crack Growth ◽  
Damage Mechanics ◽  
Experimental Studies ◽  
Creep Crack Growth ◽  
Stress Rupture ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Creep Crack ◽  
Theoretical Predictions ◽  
Rupture Criterion

Theories that have been used to predict the rate of growth of cracks due to creep are reviewed and assessed. The need is expressed for a sounder understanding of the mechanisms by which creep crack growth takes place. The aim of this paper is to answer the question: can continuum damage mechanics provide the mechanism by which cracks grow by creep? The paper reports the results of theoretical and experimental studies on internally and externally cracked, plane strain, tension members, in an aluminium alloy, in copper and in 316 stainless steel, all of which undergo high temperature creep rupture under steady loads. Theoretical predictions of lifetimes, expressed as a representative rupture stress, of damage fields and of crack growth are made by using a previously developed finite element system (Hayhurst, Dimmer & Morrison, Phil. Trans. R. Soc. Lond . 311, 103 (1984)) based on the theory of continuum damage mechanics. The theoretical predictions are shown to be in close agreement with experimental observations. The effect of the growth of continuum damage is to produce considerable stress redistribution and to cause the nullification of stress singularities. The multi-axial stress rupture criterion of the material plays an important role in the determination of lifetimes and of the planes upon which crack propagation takes place. The numerical solution procedure is automatic but requires that the constitutive equations model the elastic response, the creep strain rates, including tertiary behaviour, and the multiaxial stress rupture criterion of the material at the appropriate stress levels. Continuum damage mechanics theory is shown to be capable of modelling the propagation of cracks through material which has suffered relatively low damage.

scholarly journals Creep crack simulations using continuum damage mechanics and extended finite element method

2017 ◽  
Vol 28 (1) ◽  
pp. 3-34 ◽  
Author(s):  
VB Pandey ◽  
I V Singh ◽  
BK Mishra ◽  
S Ahmad ◽  
AV Rao ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Crack Growth ◽  
Damage Mechanics ◽  
Extended Finite Element Method ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Extended Finite Element ◽  
Creep Crack ◽  
Element Method

In the present work, elasto-plastic creep crack growth simulations are performed using continuum damage mechanics and extended finite element method. Liu–Murakami creep damage model and explicit time integration scheme are used to evaluate the creep strain and damage variable for various materials at different temperatures. Compact tension and C-shaped tension specimens are selected for the simulation of crack growth analysis. For damage evaluation, both local and nonlocal approaches are employed. The accuracy of the extended finite element method solutions is checked by comparing with experimental results and finite element solutions. These results show that the extended finite element method requires a much coarser mesh to effectively model crack propagation. It is also shown that mesh independent results can be achieved by using nonlocal implementation.

Analysis of Creep Crack Growth Behavior of the Brazed Joint Using Continuum Damage Mechanics Approach

2018 ◽  
Author(s):  
Yu-Cai Zhang ◽  
Wenchun Jiang ◽  
Shan-Tung Tu ◽  
Xian-Cheng Zhang ◽  
Guo-Yan Zhou
Keyword(s):  
Crack Initiation ◽  
Diffusion Zone ◽  
Damage Mechanics ◽  
Creep Crack Growth ◽  
Continuum Damage Mechanics ◽  
Crack Growth Behavior ◽  
Continuum Damage ◽  
Initiation Time ◽  
Creep Crack ◽  
Brazed Joint

Creep crack growth behavior of the Inconel625/BNi-2 brazed joint considering the diffusion zone at 650 °C was investigated by a continuum damage mechanics approach based on the finite element method. The results show that creep crack nucleate and develop at the region of the brazing filler metal. The crack initiates at about 0.2 mm ahead of the crack tip. When the load is 1000 N, the crack initiation time of the CT specimen is 1664 hour. While when the load is 1135 N, the crack initiation time is only about 891 hour. The simulated results correspond well with the experimental data, presenting that the used finite element method can accurately simulate the creep damage behavior of the brazed joint. When the mechanical properties of the diffusion zone are not considered, the crack initiation time and fracture time decrease significantly compared to the result with properties of the diffusion zone included, indicating that the result from the conventional simulating method without considering the diffusion zone is quite conservative compared to the experimental life of the component.

Defect Assessments at Elevated Temperature

1983 ◽  
Vol 105 (3) ◽  
pp. 263-268 ◽  
Author(s):  
R. A. Ainsworth ◽  
I. W. Goodall
Keyword(s):  
Damage Mechanics ◽  
Creep Crack Growth ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Initiation Time ◽  
Creep Crack ◽  
Reference Stress ◽  
Statistical Approaches ◽  
Assessment Requirements ◽  
Fast Fracture

Methods are described for assessing acceptable defect sizes for plant in high temperature service. At one extreme of behavior, that of creep ductile response, failure is governed by continuum damage mechanics which may be analyzed using finite element methods or more approximately by reference stress techniques. In less ductile cases failure can occur through the initiation and growth of a dominant creep crack. For this case the paper outlines how the assessment requirements may be based on an estimate of the initiation time and a method for calculating this initiation time is given. When the initiation time is small, the assessment also requires an estimate of the time taken in the creep crack growth stage and both empirical correlation and statistical approaches for analyzing this stage are described. Finally the paper outlines how fast fracture and ductile instability can be included in determining repair criteria for use with the various assessment methods.

Life Prediction of Solder Joints by Damage and Fracture Mechanics

1996 ◽  
Vol 118 (4) ◽  
pp. 193-200 ◽  
Author(s):  
S. H. Ju ◽  
B. I. Sandor ◽  
M. E. Plesha
Keyword(s):  
Fatigue Life ◽  
Fracture Mechanics ◽  
Crack Growth ◽  
Damage Mechanics ◽  
Solder Joints ◽  
Continuum Damage Mechanics ◽  
Computer Time ◽  
Initial Crack ◽  
Continuum Damage ◽  
Growth Path

Much research has been done on Surface Mount Technology (SMT) using the Finite Element Method (FEM). Little of this, however, has employed fracture mechanics and/or continuum damage mechanics. In this study, we propose two finite element approaches incorporating fracture mechanics and continuum damage mechanics to predict time-dependent and temperature-dependent fatigue life of solder joints. For fracture mechanics, the J-integral fatigue formula, da/dN = C(δJ)m, is used to quantify fatigue crack growth and the fatigue life of J-leaded solder joints. For continuum damage mechanics, the anisotropic creep-fatigue damage formula with partially reversible damage effects is used to find the initial crack, crack growth path, and fatigue life of solder joints. The concept of partially reversible damage is especially novel and, based on laboratory tests we have conducted, appears to be necessary for solder joints undergoing cyclic loading. Both of these methods are adequate to predict the fatigue life of solder joints. The advantage of the fracture mechanics approach is that little computer time is required. The disadvantage is that assumptions must be made on the initial crack position and the crack growth path. The advantage of continuum damage mechanics is that the initial crack and its growth path are automatically evaluated, with the temporary disadvantage of requiring a lot of computer time.

Virtual Methods in Creep Crack Growth Predictions in 316H Stainless Steels

2007 ◽  
Author(s):  
Masataka Yatomi ◽  
Kamran M. Nikbin
Keyword(s):  
Crack Growth ◽  
Plane Strain ◽  
Stainless Steels ◽  
Creep Crack Growth ◽  
Crack Propagation Rate ◽  
Creep Model ◽  
Elastic Plastic ◽  
Creep Crack ◽  
Plastic Creep ◽  
Plane Strain Crack

The paper discusses numerically based virtual techniques of creep crack growth predictions in a fracture mechanics component. The material properties used are for 316H stainless steels and the constitutive behaviour of the steel is described by a power law creep model. A damage-based approach is used to predict the crack propagation rate in compact tension (C(T)) specimens and the data are correlated against an independently determined C* parameter. Elastic-plastic-creep analyses are performed using two different crack growth criteria to predict crack extension under plane stress and plane strain conditions. The NSW and NSW-MOD strain exhaustion models are applied to compare to the experimental data and FE predictions. The plane strain crack growth rate predicted from the numerical analysis is found to be less conservative than the plane strain NSW model but more conservative than plane strain NSW-MOD model, for values of C* within the limits of the present creep crack growth testing standards. At higher loads and C* values, the plane strain crack growth rates, predicted using an elastic-plastic-creep material response, approach is considered and compared to the plane strain NSW-MOD model.

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