Bayesian estimation of crack initiation times from service dataLockheed C-130 Hercules aircraft have during their service life been periodically inspected and growing cracks around rivet holes were recorded. This record has recently been used to determine the statistical distributions of crack initiation times and the distribution of initial crack sizes. When crack initiation times are calculated from such cracks, by backward extrapolation of the growth relation, the resulting distribution of crack initiation times will indicate a preponderance of short times to crack initiation. If however, such distributions are combined with the reliability of the inspection procedure, the statistical distribution of missed initiation times can be estimated. The method used is based on Bayes theorem which permits the calculation of the 'prior' distribution (initiation times before inspection) from a knowledge of the 'posterior' distribution (initiation times obtained from the inspection) and a 'likelihood function' (reliability of the inspection) procedure. The results indicate that during an early inspection a large percentage of initiation times will be missed and that the fraction of located initiation times increases during later inspections.
Document ID
19770042890
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Heller, R. A. (Virginia Polytechnic Institute and State University Blacksburg, Va., United States)
Stevens, G. H. (Tennessee Valley Authority Tenn., United States)
Date Acquired
August 8, 2013
Publication Date
January 1, 1977
Subject Category
Structural Mechanics
Report/Patent Number
AIAA PAPER 77-383
Meeting Information
Meeting: Conference on Structures, Structural Dynamics and Materials