Fatigue-Life Prediction and Design for Uncracked and Cracked Components: Deterministic, A- and B-Basis Probabilistic, and Reliability Target Approaches

Abstract Based on a recently developed multi-scale fatigue-fracture-NDE reliability model for uncracked and cracked pipes (see Fong-Marcal-Rainsberger-Heckert-Filliben-Doctor-Finney, PVP2021-62169), we apply the same modeling technique to a comparative study of three approaches to fatigue-life prediction and design: Approach (1). Deterministic. Approach (2). Probabilistic using the A- and B-basis design allowables. Approach (3). Reliability Target using the concept of a co-reliability or an upper bound of failure probability as a tool for damage assessment and control. To illustrate the comparison of the three approaches to both uncracked and cracked components, we present numerical examples for generic components of three engineering materials at room temperatures, namely, (a) AISI 4340 steel for piping, (b) 2024-T4 aluminum for aircraft structures, and (c) BK-7 borosilicate crown glass for aircraft windows. In particular, for cracked components inspected by NDE personnel with varying probability of detection (POD) qualifications, we find both Approach (1) and Approach (2) inadequate as a guide for maintenance decision-making and compliance with the ASME Boiler and Pressure Vessel Section XI Division 2 Reliability and Integrity Management (RIM) Code. Significance and limitations of the methodology for Approach (3) based on the concepts of co-reliability and reliability target are presented and discussed. Some concluding remarks and future work are included at the end of this paper.