PSI - Issue 42

Tereza Juhászová et al. / Procedia Structural Integrity 42 (2022) 1090–1097 Juhaszova/ Structural Integrity Procedia 00 (2019) 000–000

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see e.g. Yawas et al. (2014), Liu et al. (2022), Klusák (2021). On the other hand, larger structures are exposed to cyclic loading as well, which can be a result of traffic loading or weather conditions. To consider the influence of fatigue for designing, important documents were introduced, one of which is Eurocode 3 (2004). Disadvantage of this document lays in considering undamaged component, meaning without presence of cracks. As generally known, the presence of discontinuity leads to change in behavior of components and causing repositioning of stress fields. Thus, considering fracture mechanics in civil engineering and structure design is necessary. Nomenclature a crack length B thickness of specimen C, m Paris’ law material constants CMOD crack mouth opening displacement FCGR fatigue crack growth rate FEM finite element method K I stress intensity factor for mode I LEFM linear elastic fracture mechanics N number of cycles R stress ratio SENB single-edge notched bending SIF stress intensity factor TPB three-point bending To understand the fatigue behavior of large structures, fatigue testing needs to take place on larger elements where loading approximates real situation that occurs in load bearing systems. Therefore, this paper investigates the stainless steel specimens loaded in a three-point bending under a cyclic load, so the testing simulates beam with single load, which is typical loading for bridge components. Stainless steel as a material of load-bearing system has come to the forefront in the beginning of this century, due to mechanical properties, resistance to corrosion and also visual aspects, see Baddoo (2008), Gardner (2005). In the paper, stainless steel beams of grade AISI 304 were investigated, as it is widely used in civil engineering structures, Gedge (2008). Structural components made from metallic materials produced by various companies exhibit variability in material properties. This variability occurs in all types of structural components. When life safety is a concern, service loads must be consistent with extremely high reliability, where probabilities of failure, P f , of less than 10 −6 may be the design goal. Therefore, to complement such experiments, a sound theoretical understanding of statistical failure mechanisms is required, and this knowledge must be embodied in predictive models that treat the subtleties of these mechanisms, see e.g. Krejsa et al. (2018), Kala (2019), Kala et al. (2019), Janas et al. (2020), Kala (2021), etc. To describe fatigue behavior of crack in structural components, Paris’ law (Paris & Erdogan, 1963) was used, describing the relation between fatigue crack growth rate (FCGR) and stress intensity factor (SIF) value. This was done by coupling numerical model made in finite element method (FEM) software Ansys Mechanical with obtained fatigue experiments. Comparison of fatigue crack behavior in AISI 304 steel was studied on a plate 10  50 mm 2 by different producers and discrepancies in experimental methods were analyzed and discussed. 2. Studied structural component made from AISI 304 As a structural component in our study was selected plate 10 mm × 50 mm, see Fig. 1(a), made from AISI 304 steel made at two different producers hereafter referred to as A (Asia – Indian company) and E (Europe – Italian company) was investigated. The chemical composition of the investigated steel grades fulfills the EN 10025-2:2004 standard. The composition according to the material lists of the investigated materials is given in Tab.1. Heat treatment for all studied bars was annealing at 1050°C followed by water quenching. Mechanical properties guaranteed by producers are presented in Tab. 2. Specimen’s location for tensile test was selected through cross section to catch the change of materials properties trough and axes of specimen was selected in direction of the supposed crack initiation to be