1014 過大荷重によるき裂材の疲労ΔK_<th>向上に関する研究 : 第2報 : 応力比(S)依存性の解析的検討(OS10-4 供用エネルギー機器の経年変化と健全性評価-疲労き裂-)

概要

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This study proposes an innovative method for aesting fatigue crack, and making harmless the cracks by overload. By overloading, compressive residual stress is introduced ahead of the crack The residual stress reduce K values and arrest the crack. By theory, ΔK_<th> increase with increasing Kov (K value by overload) and the nominal threshold values were given by the equation when stress ration was negative: Δ^NK_<th>^s=C+DKov. Where C is ΔK_<th>^o and D is a proportional constant and 0.24〜0.27. Experimental results showed that D showed good agreement with theory. Thus, if Δ^NK_<th>^s is enough larger than applied K and ΔK values, crack is not able to grow and can be made harmless.
2010-10-09