• Nuclear Engineering and Technology
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• v.55 no.5
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• pp.1616-1629
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• 2023

To quantify the conservatism of existing ASME strain-based evaluation methods for seismic loading, this paper presents very low cycle fatigue test data of elbows under various cyclic loading conditions and comparison of evaluation results with experimental failure cycles. For strain-based evaluation methods, the method presented in ASME BPVC CC N-900 and Sec. VIII are used. Predicted failure cycles are compared with experimental failure cycle to quantify the conservatism of evaluation methods. All methods give very conservative failure cycles. The CC N-900 method is the most conservative and prediction results are only ~0.5% of experimental data. For Sec. VIII method, the use of the option using code tensile properties gives ~3% of experimental data, and the use of the material-specific reduction of area can reduce conservatism but still gives ~15% of experimental data.

• Journal of Power System Engineering
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• v.18 no.5
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• pp.122-128
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• 2014

Generally, the mechanical components and structures are joined by many welding techniques, and therefore the welded joints are inevitable in the construction of structures. The Alloy 617 was initially developed for high temperature applications above $800^{\circ}C$. It is often considered for use in aircraft and gas turbines, chemical manufacturing components, and power generation structures. Especially, the Alloy 617 is the primary candidate for construction of intermediate heat exchanger (IHX) on a very high temperature reactor (VHTR) system. In the present paper, the low cycle fatigue (LCF) life of Alloy 617 base metal (BM) and the gas tungsten arc welded (GTAWed) weld joints (WJ) are evaluated by using the previous experimental results under strain controlled LCF tests. The LCF tests have been performed at room temperature with total strain ranges of 0.6, 0.9, 1.2 and 1.5%. The LCF lives for the BM and WJ have been evaluated from the Coffin-Manson and strain energy based life methods. For both the BM and WJ, the LCF lives predicted by both Coffin-Manson and strain energy based life methods was found to well coincide with the experimental data.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.20 no.2
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• pp.122-129
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• 2024

The International Atomic Energy Agency (IAEA) highlights the importance of maintaining the structural integrity of key safety equipments and facilities not only under design-basis earthquake but also beyond-design-basis earthquake. To ensure this integrity, it is essential to utilize appropriate elastic-plastic fatigue analysis methods for earthquake resistance. In this study, a parametric study of FE simulation for piping elbow under dynamic cyclic loading was conducted by varying the damping ratio and element density for the pipe elbow specimen for application of the JSME Code Case for elastic-plastic fatigue analysis. The elbow used in this research was made from SA403 WP316 stainless steel, used in primary and secondary piping systems of nuclear power plants. To simulate the pipe elbow test, 3-D elastic-plastic FE analysis were performed using the bi-linear kinematic hardening model. Dynamic cyclic loadings were applied at room temperature. The FE analysis was compared with experimental acceleration response and the opening-closing displacement data.