Issue 39

M. Krejsa et alii, Frattura ed Integrità Strutturale, 39 (2017) 143-159; DOI: 10.3221/IGF-ESIS.39.15 143 Focussed on Modelling in Mechanics Probabilistic prediction of fatigue damage based on linear fracture mechanics M. Krejsa, L. Koubova, J. Flodr, J. Protivinsky, Q. T. Nguyen VSB-Technical University of Ostrava, Faculty of Civil Engineering, Department of Structural Mechanics, Ludvika Podeste 1875/17, 708 33 Ostrava – Poruba, Czech Republic martin.krejsa@vsb.cz, http://orcid.org/0000-0003-0571-2616 lenka.koubova@vsb.cz , http://orcid.org/0000-0002-8373-0572 jakub.flodr.st@vsb.cz , jiri.protivinsky@vsb.cz, qui.nguyen.thanh.st@vsb.cz A BSTRACT . Paper describes in detail and gives example of the probabilistic assessment of a steel structural element subject to fatigue load, particular attention being paid to cracks from the edge and those from surface. Fatigue crack damage depends on a number of stress range cycles. Three sizes are important for the characteristics of the propagation of fatigue cracks - the initial size, detectable size and acceptable size. The theoretical model of fatigue crack progression in paper is based on a linear fracture mechanics. When determining the required degree of reliability, it is possible to specify the time of the first inspection of the construction which will focus on the fatigue damage. Using a conditional probability, times for subsequent inspections can be determined. For probabilistic calculation of fatigue crack progression was used the original and new probabilistic methods - the Direct Optimized Probabilistic Calculation (“DOProC”), which is based on optimized numerical integration. The algorithm of the probabilistic calculation was applied in the FCProbCalc code (“Fatigue Crack Probabilistic Calculation”), using which is possible to carry out the probabilistic modelling of propagation of fatigue cracks in a user friendly environment very effectively. K EYWORDS . Direct Optimized Probabilistic Calculation; DOProC; Fatigue crack; Linear fracture mechanics; Probability of failure; Inspection of structure. Citation: Krejsa, M., Koubova, L., Flodr, J., Protivinsky, J., Nguyen, Q. T., Probabilistic prediction of fatigue damage based on linear fracture mechanics, Frattura ed Integrità Strutturale, 39 (2017) 143-159. Received: 11.07.2016 Accepted: 02.09.2016 Published: 01.01.2017 Copyright: © 2017 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. I NTRODUCTION umerous numerical methods, mostly based on the finite element method (FEM), have been developed to aid in the understanding of the behaviour of the fatigue phenomena, e.g. [7, 31]. Even though the use of S-N curves is well established in the design of structures, information relating to time-variable load and particularly to the N