Papers by Keyword: Single Overload

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Authors: Kwang Hwan Oh, C.K. Jung, Y.C. Yang, Kyung Seop Han
Abstract: This study investigated acoustic emission behavior during fatigue crack growth test under constant and variable amplitude loading in 304 stainless steel. To describe the acoustic emission behavior, counts rate(dη/dn) was related with stress intensity factor range (SIFR, ΔK) in log-log plot. As a result of test, the relationship was represented a curve, which forms rise and fall behavior in counts rate as the SIFR increases. AE response to a single overload was sudden drop and slow recovery in counts rate, which was similar to crack growth retardation behavior. Under block loading, counts rate of each loading block was same as that of constant amplitude loading. Overall experimental results indicated that stress intensity factor controls the counts rate (dη/dn) as well as crack growth rate (da/dn) regardless of load range or crack length.
Authors: He Xue, Yuan Kui Gui, Wei Bing Wang, Xiao Bo Li, Ying Ru Wang, Xiao Qing Tao, Rui Guo
Abstract: To understand the effect of a single overload on the fracture behavior in welded joints, the stress and strain field at the crack tip in a safe-end dissimilar metal welded joint in nuclear pressure vessel is simulated and analyzed by using the elastic-plastic finite element method in the paper, in which the mechanical heterogeneity in welded joint is emphatically considered. The investigating results indicate that the tensile plastic strain at crack tip increases, but the tensile stress decreases as a single overload increases, and the influence of a single overload on tensile strain is larger than one on tensile stress, which provide a theoretical basis for quantitatively estimating the crack growth rate of environmentally assisted cracking in the welded structural material of pressure vessel and piping in the nuclear power plant.
Authors: Aleš Materna, Vladislav Oliva
Abstract: A 3D elastic-plastic FEM model for prediction of planar fatigue crack growth is presented. The model is based on the concept of local low-cycle fatigue of a small material volume in front of a high cycle crack. A local crack front advance is modelled by the successive release of finite element mesh nodes in the plane of propagation. The release of the nodes is controlled by the value of the Smith-Watson-Topper fatigue damage parameter in the surrounding elements. The effect of the single tensile overload on the fatigue crack growth and on the fatigue crack front shape is modelled.
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