This paper presents a method to estimate remaining fatigue lives of railway bridge members subjected to time‐dependent corrosion. The method addresses effects of material loss due to general (uniform) corrosion and fatigue strength degradation of material due to corrosive environment. The method mainly consists of stress history, which is obtained by considering the effect of time‐dependent loss of material, full‐range S–N curve, which represents the corrosive environment, and sequential law, which takes the loading sequence effect more precisely in to account than Miner's rule. Initially, nonlinear behaviour of material loss over time (i.e. time‐dependent growth of corrosion wastage) is discussed, and hence, necessary formulae to calculate time‐dependent cross‐sectional properties are comprehensively presented. Then finite element analysis‐based procedure is clearly proposed to predict stress histories of corroded members. A technique is introduced to obtain the full‐range S–N curve for the corroded structural detail. The concept of sequential law is summarized with the algorithm, and then the proposed method is applied to predict the remaining fatigue lives of the corroded members of a railway bridge. The predicted remaining lives were compared with the previous method‐based estimations, and comparisons reveal the range of 16–47% reduction of fatigue lives of critical members when time‐dependent corrosion is taken into account. Also, the results reveal that the corroded members of smaller cross‐sectional area are most vulnerable for fatigue damage. Finally, significance of the proposed method is confirmed.
A vast amount of research has been carried out towards the goal of quantifying changes related to the fatigue damaging process in materials throughout the fatigue life. However, no recommended practice has been developed for the experimental measurement of fatigue damage before a macroscopic crack has been initiated. Therefore, this paper reviews the existing fatigue damage detection and measurement techniques on the basis of both momentum within the research field and their being considered non-destructive. The techniques are separated into two categories, namely, fatigue crack monitoring and fatigue damage monitoring. The parameters of these techniques, which quantify the physical and mechanical changes of the materials during the fatigue life, were critically reviewed in regard to the mechanism behind the change, limitations, shortcomings, etc. The acoustic emission, hardness, ultrasonic, magnetic and potential drop methods are applicable for in-situ measurements while positron annihilation and X-ray diffraction are more suitable for laboratory assessments. Even though all the revived methods are applicable for metals, acoustic emissions, X-ray diffraction, ultrasonic, strainbased and thermometric methods are also suitable for composites. The reliability, advantages, weaknesses, case/ material dependency and applicability of each method are compared and tabulated for making a framework for choosing suitable technique for fatigue crack or damage detection of material or components.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.