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The study of the dissipation heat flow and the acoustic emission during the fatigue crack propagation in the metal A N Vshivkov, A Yu Iziumova, I A Panteleev et al. noAbstract. Fatigue is one of the main causes of failures in mechanical and structural systems. Offshore installations, in particular, are susceptible to fatigue failure due to their exposure to the combination of wind loads, wave loads and currents. In order to assess the safety of the components of these installations, the expected lifetime of the component needs to be estimated. The fatigue life is the sum of the number of loading cycles required for a fatigue crack to initiate, and the number of cycles required for the crack to propagate before sudden fracture occurs. Since analytical determination of the fatigue crack propagation life in real geometries is rarely viable, crack propagation problems are normally solved using some computational method. In this review the use of the finite element method (FEM) and the extended finite element method (XFEM) to model fatigue crack propagation is discussed. The basic techniques are presented, together with some of the recent developments. IntroductionComponents which are subjected to fluctuating loads are found virtually everywhere: Vehicles and other machinery contain rotating axles and gears, pressure vessels and piping may be subjected to pressure fluctuations (e.g. water hammer) or repeated temperature changes, structural members in bridges are subjected to traffic loads and wind loads, while those in ships and offshore structures are subjected to the combination of wind loads, wave loads and currents. If the components are subjected to a fluctuating load of a certain magnitude for a sufficient amount of time, small cracks will nucleate in the material. Over time, the cracks will propagate, up to the point where the remaining cross-section of the component is not able to carry the load, at which the component will be subjected to sudden fracture [1]. This process is called fatigue, and is one of the main causes of failures in structural and mechanical components [2]. In order to assess the safety of the component, engineers need to estimate its expected lifetime. The fatigue life is the sum of the number of loading cycles required for a fatigue crack to nucleate/initiate, and the number of cycles required for the crack to propagate until its critical size has been reached [2,3]. In this paper, computational methods to estimate the lifespan of a propagating crack whose initial geometry is known will be considered.Estimations of the fatigue crack propagation rate, da/dN, are normally based on a relation with the range of the stress intensity factor, ΔK, which is a linear elastic fracture mechanics (LEFM) parameter for quantifying the load and geometry of the crack. Paris, Gomez and Anderson [4] first proposed the existence of such a relation in 1961, and its simplest form is the Paris law [5]:

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As offshore structures are reaching their original design life, effective repair and life-extension techniques are required, in order to ensure continued safe operation. A stop hole may be drilled at the end of a crack, in order to delay further fatigue crack propagation. To compare the stop hole technique with other relevant repair techniques, its effect needs to be modelled. Here, a procedure for modelling the stop hole-induced fatigue crack growth delay for a crack propagating under mixed-mode I + II conditions is presented. The procedure combines the S–N curve for fatigue crack initiation and the Paris law for fatigue crack propagation, with models for mixed-mode crack propagation and finite-element analysis of the cracked geometry. The failure criterion inherent in the S–N curves is used to define the transition between initiation and propagation. The procedure is implemented on an example, and the importance of considering the mixed-mode conditions is indicated.