Initial Fatigue Crack Growth Behavior in a Notched Component (Report V) : Assessment of Initial Defect in Respect to Fatigue Life of a Notched Component(Mechanics, Strength & Structural Design)

概要

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The present report is intended to apply Elasto-Plastic Fracture Mechanics (EPFM) for assessment of initial defect and for fatigue design in welding steel structures. Considering fatigue design methods of welding steel structures, assessment methods of initial defect in notch field were classified into three cases. In the Case 1 of fatigue design based on classification of joints, when quality level to initial defect was specified with class of joints concerned, safety factor to fatigue life varied with configuration of component. In the Case 2A that fatigue design was based on classification of joints and frature mechanics was applied for assessment of initial defect, when allowable size of initial defect was assessed by ΔJ and experiment, the size depended upon stress level and materials (SS41 & HT80). And in the Case 2B of fatigue based on EPFM to consider the previously determined size of initial defect, it could be confirmed that to raise section (or to lower sectional force) was beneficial when fatigue strengh in low cycle region was significant, and to lower tensile residual stress was beneficial when fatigue strength in high cycle region was significant.
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