Dielectric-breakdown-type crack-growth models and the fractal distribution of earthquake faults

1995 ◽  
Vol 52 (2) ◽  
pp. 1476-1479
Author(s):  
Xian-zhi Wang ◽  
Yun Huang
Keyword(s):  
Crack Growth ◽  
Dielectric Breakdown ◽  
Growth Models ◽  
Fractal Distribution ◽  
Earthquake Faults

Effective Modeling of Fatigue Crack Growth in Pipelines

2012 ◽  
Author(s):  
Steven J. Polasik ◽  
Carl E. Jaske
Keyword(s):  
Fatigue Crack ◽  
Stress Intensity ◽  
Fatigue Crack Growth ◽  
Fracture Mechanics ◽  
Crack Growth ◽  
Growth Models ◽  
Critical Parameters ◽  
Operating Pressure ◽  
Mechanics Model ◽  
Key Variables

Pipeline operators must rely on fatigue crack growth models to evaluate the effects of operating pressure acting on flaws within the longitudinal seam to set re-assessment intervals. In most cases, many of the critical parameters in these models are unknown and must be assumed. As such, estimated remaining lives can be overly conservative, potentially leading to unrealistic and short reassessment intervals. This paper describes the fatigue crack growth methodology utilized by Det Norske Veritas (USA), Inc. (DNV), which is based on established fracture mechanics principles. DNV uses the fracture mechanics model in CorLAS™ to calculate stress intensity factors using the elastic portion of the J-integral for either an elliptically or rectangularly shaped surface crack profile. Various correction factors are used to account for key variables, such as strain hardening rate and bulging. The validity of the stress intensity factor calculations utilized and the effect of modifying some key parameters are discussed and demonstrated against available data from the published literature.

Analysing crack growth

1998 ◽  
Vol 212 (3) ◽  
pp. 157-166 ◽  
Author(s):  
M Newby
Keyword(s):  
Bayesian Analysis ◽  
Crack Length ◽  
Crack Growth ◽  
Failure Time ◽  
Growth Models ◽  
Accelerated Failure Time ◽  
Deterministic Models ◽  
Stochastic Growth Models ◽  
Standard Linear ◽  
Fully Bayesian

Deterministic models of crack growth can be fitted to experimental data. This paper shows that stochastic growth models are easy to use and provides a simple framework for data analysis. A simple transformation allows the standard linear regression model to be used and opens the way for a fully Bayesian analysis. The Bayesian analysis allows the incorporation of prior information and coherent predictions of crack length to be made. The parameters of the Paris-Erdogan model are readily evaluated directly from crack length data without the need for intermediate estimates of the crack growth rate. The approach lends itself to the analysis of properly designed experiments to determine the effect of environmental factors on the parameters of the Paris-Erdogan equation through the medium of accelerated failure time models. The paper also emphasizes the need for adequate communication between experimenter and statistician to ensure efficient experimental designs.

Evaluations of some Stochastic Fatigue Crack Growth Models through Experimental Verification

2018 ◽  
Vol 928 ◽  
pp. 221-228
Author(s):  
Chih Chung Ni
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Growth Models ◽  
Random Factor ◽  
Normal Probability ◽  
Log Normal

The study is focused on the comparisons among three stochastic fatigue crack growth models through evaluations of experimental data. The first model assumed that the coefficient and exponent parameters of Paris-Erdogan law are mutually dependent normal random variables. The second model assumed that the fatigue crack growth rate equals to the deterministic Paris-Erdogan law multiplied by a stationary log-normal random factor while the third model proposed by the author was assumed that the fatigue crack growth rate equals to a deterministic polynomial in terms of fatigue crack size multiplied by a stationary log-normal random factor. Compact-tension specimens cut from a 2024-T351 aluminum-alloy plate were used for fatigue crack growth experiments under constant loads performed on thirty specimens. The normal probability paper for the first model was investigated to show the validity of the normal random parameter, and the log-normal probability papers for the second and third models were also investigated to show the validity of log-normal assumption of the random factors. The investigations on the probability of crack exceedance and distribution of random time of the three models were also made, and the comparisons of the results for all models were made as well.

scholarly journals Analysis of Surface Crack using Various Crack Growth Models

2020 ◽  
Vol 1529 ◽  
pp. 042074
Author(s):  
M R M Akramin ◽  
M S Marizi ◽  
M N M Husnain ◽  
M Shamil Shaari
Keyword(s):  
Crack Growth ◽  
Surface Crack ◽  
Growth Models

scholarly journals Slow crack growth: Models and experiments

2007 ◽  
Vol 146 (1) ◽  
pp. 341-356 ◽  
Author(s):  
S. Santucci ◽  
L. Vanel ◽  
S. Ciliberto
Keyword(s):  
Crack Growth ◽  
Growth Models ◽  
Slow Crack Growth

The Influence of Creep-Fatigue Interaction on High Temperature Crack Growth in 316 Steel Weldments

2009 ◽  
Author(s):  
C. M. Davies ◽  
David W. Dean ◽  
A. N. Mehmanparast ◽  
K. M. Nikbin
Keyword(s):  
High Temperature ◽  
Crack Growth ◽  
Static Load ◽  
Growth Models ◽  
Creep Crack Growth ◽  
Crack Tip ◽  
Parent Material ◽  
Creep Crack ◽  
Static Creep ◽  
Temperature Crack

High temperature crack growth in weldments is of great concern and generally occurs along the boundary between the heat affected zone (HAZ) and parent material (PM) of welded components in high temperature plants. Static creep and low frequency cyclic crack growth tests have been performed on compact tension, C(T), specimens manufactured from sections taken from a 316 steel weldment at 550 °C, where the crack tip was located along the fusion line within the HAZ. The data has been analyzed in terms of both the creep-brittle and creep-ductile crack tip parameters, K and C*, respectively. The cyclic test results have been compared to static creep crack growth tests on 316 steel weldments and homogeneous parent material specimens, and to crack growth models. The cracking rates of the cyclic crack growth tests are found to be higher than that of the of the static load creep crack growth tests on weldments. The data may be bounded by the high frequency fatigue and the static load creep crack growth predictions. However, further work is required to establish the fatigue and subsequently the creep component of the cyclic load crack growth tests on weldments.

Sign in / Sign up

Export Citation Format

Share Document