| Summary: | 碩士 === 國立臺灣大學 === 機械工程研究所 === 81 === The objective of the present study is to investigate the
failure mechanisms of piping systems and to develop a
probabilistic fracture mechanics model for the reliability
analysis of piping systems. In the failure analysis, it is
concluded through the present study that major causes for the
failure of piping systems include intergranular stress
corrosion crack, thermal fatigue crack, vibratory fatigue,
water hammer, erosion and cavitation. All these causes are
closely related to the defect sizes, loading conditions and
material properties of the structures. Therefore, in the
probabilistic fracture mechanics approach, these factors are
considered random and treated as random variables. They are
fitted by appropriate probability density functions before a
further quantitative reliability analysis is taken. Some
elementary concepts of system reliability are then employed to
estimate the reliability of an existent piping system by taking
these random factors into consideration. A numerical example is
given at the end of the present study. The example illustrates
the use of the proposed analysis in the reliability assessment
of a piping system existed in a German nuclear power plant. It
is found that the failure probability of the piping system is
5.4*10^{-7} per weld area and 1.4*10^{-10} for the entire system
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