Reliability-based fracture analysis with uncertainty on material degradation

Abstract

Purpose – The purpose of this paper is to quantify uncertainty design parameters of long service usage material and including their effects explicitly in analysis of fracture toughness for evaluation of reliability indexes. Design/methodology/approach – In this paper structural reliability algorithm was incorporated into comprehensive finite element software. In this algorithm, the limit state function and relative gradient of uncertainty parameters has been determined using finite element model. Findings – Results from this paper show that the effect of material degradation due to long service usage on the Young’s modulus for corroded samples and non-corroded samples are approximately 5 and 2.5 percent below the handbook value, respectively. The uncertainty in Young’s modulus is small, the randomness is unsymmetrical, and the dispersion is more above the mean than below the mean. The failure probability increases with the increasing uncertainty of Young’s modulus, and can be much larger than the probabilities calculated for a deterministic elasticity. Originality/value – Reliable structural analysis of aging aircraft is crucial of safe operation.