目前在進行結構組件實際運轉中之疲勞壽限評估時，是將負荷歷程用循環計數法分解成許多等振幅的循環，配合等振幅下之材料性質求取疲勞損傷量，再由疲勞損傷累積理論求取壽限值。雖然在計算過程中可考慮平均應力或次序效應的影響，但對於一般的準隨機負荷，仍缺乏直接的數據來比較預測壽限與實際壽限間之差異，以評估不同的疲勞壽限預測方式之優劣。本計畫將以反應器壓力槽材料SA533鋼材為探討對象，進行變動振幅負荷下之高週疲勞試驗，求取在不同應力水準、不同平均應力下之疲勞壽限，並與理論預測結果作比較，探討疲勞壽限評估模式之適用性及準確性。 Fatigue life prediction techniques play an important role in the design of mechanical components and reactor pressure vessels (RPV). The fatigue process involves a period of damage accumulation leading to crack initiation followed by a period of crack growth, until the critical flaw size is reached. The total life of a component is the summation of the initiation and propagation phases. In this project, we deal with the prediction of crack initiation life with stress-life (S-N) approach. The current fatigue design method (S-N approach) of components under real loading history includes several steps: fatigue strength correction, mean stress correction, cycle counting, damage accumulation, overload correction etc. The fatigue properties under constant amplitude loading are commonly used. But under variable amplitude loading condition, there is still little data to verify the availability of fatigue model. The present project will develop a computer program to predict the fatigue crack initiation life of a component subject to complex loading. The high cycle fatigue will be conduct on a reactor pressure vessel steel SA533-B1. Three SAE loading histories include various types of mean stress are adopted. Variable amplitude fatigue tests under different stress levels are performed. From the comparison of predicted and experimental results; we can understand the validity and accuracy of various fatigue life prediction models in the RPV structure. 研究期間：9001 ~ 9012
