Open Access

ARTICLE

Effect of correct statistical description of fatigue crackpropagation data on the time to first inspection

G. Bertrand¹

1 Dept. Structural Reliability Airbus- Germany e-mail: gerd.bertrand@airbus.com

Structural Durability & Health Monitoring 2005, 1(3), 185-192. https://doi.org/10.3970/sdhm.2005.001.185

Abstract

Each maintenance strategy demands for the definition of an inspection threshold and further inspection intervals. A general criterion for the calculation of the time to first inspection is high probability of detection of a certain crack size and low failure probability in case a predicted crack size was not detected. The proposed method demonstrates that a top down analysis of crack development from critical sizes to detectable sizes reveals an economic benefit with respect to the frequency of inspections. The dispersion of fatigue stress cycles at rupture obtained from component tests at riveted lap joints is transformed to the distribution of time to predicted detectable crack sizes using an analogy between the structure of Wöhlers- and Paris equation. The distribution function of stress cycles at various crack stages is then derived from integration of the governing stochastic limit state equation.

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Keywords

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