Title: Thermal Frequency Response Studies of an Hollow Cylinder Subject to Loads of Different Amplitude and Shape
Authors: PAFFUMI ElenaNILSSON Karl-FredrikTAYLOR Nigel
Citation: NUCLEAR ENGINEERING AND DESIGN vol. 240 p. 1355-1362
Publication Year: 2010
JRC N°: JRC55568
ISSN: 0029-5493
URI: www.elsevier.com/locate/nucengdes
DOI: 10.1016/j.nucengdes.2010.02.036
Type: Articles in periodicals and books
Abstract: Thermal fatigue is an important degradation mechanism, which must be considered in life management of nuclear plant piping systems. The analysis is very complex due to a number of complicating factors, with the determination of the load as the primary one. There is clearly a need for simplified engineering approaches, such as simulating the spectrum load by a constant frequency thermal load with the nominal temperature difference between mixing fluids. The fatigue life is determined by the frequency that gives the shortest life using fatigue curves for initiation and Paris law for crack propagation. This paper analyses three aspects that affect the conservatism of such an approach: the thermal load shape (sinusoidal or square-shaped), the structural boundary conditions at the edges of the modelled pipe (traction free or clamped) and the defect shape (circumferential or elliptic). Furthermore it is shown how the methodology can be used as determine screening criteria i.e. a lower limit of the temperature difference below which there will be no component failure due to thermal fatigue.
JRC Directorate:Energy, Transport and Climate

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