Title: A Prospective Study for Probabilistic Approach of Thermal Fatigue in Mixing Tees
Authors: RADU VasilePAFFUMI ElenaTAYLOR NigelNILSSON Karl-Fredrik
Publisher: European Commission
Publication Year: 2009
JRC N°: JRC48003
ISSN: 1018-5593
Other Identifiers: EUR 23570 EN
URI: http://publications.jrc.ec.europa.eu/repository/handle/JRC48003
Type: EUR - Scientific and Technical Research Reports
Abstract: The work performs a prospective study on probabilistic approach of thermal fatigue in mixing tees (Civaux 1 damage case) by means of the limit state function and Monte Carlo simulation. It is based on previous work where a deterministic assessment for thermal fatigue crack growth in high-cycle loadings, under the large nonlinear gradient stress profiles through wall-thickness due to sinusoidal thermal loading, has been done.The probabilistic approach considers variability in initial crack depth and Paris law C scaling parameter by means of specific probability density distributions. The crude Monte Carlo Simulations are performed using specific routines implemented in MATLAB software with Statistics Toolbox, and probabilities of failure are derived using the failure function which is defined based on a limit state given by the critical crack depth. The results were checked against predictions from empirical cumulative distribution and a good agreement was found. An important task was to estimate distribution function for fatigue lives after finding probabilities failure associated with corresponding fatigue lives by means of the failure function approach. Using specific MATLAB functions from Statistic Toolbox, for both axial and circumferential crack growth the pdf, associated mean value of the fatigue life and CoV have been estimated. The log-normal distribution has been found to best fit the results from failure function approach with MCS, for both cases.
JRC Directorate:Energy, Transport and Climate

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