表面き裂材の疲労寿命とき裂貫通挙動 : 第3報、引張りと曲げの組合せ応力を受ける場合

元データ 1989-08-25 一般社団法人日本機械学会

概要

The LBB (leak-before-break) design is one of the most important subjects for the evaluation and the assurance of safety in pressure vessels, piping systems, LNG carriers and various other ;structures. In the LBB design, it is necessary to evaluate precisely the lifetime of steel plate. 'Furthermore, the change in crack shape that occurs during the propagation after through thickness s of paramount importance. For this reason, in a previous report, the authors proposed a simplified evaluation model for the stress intensity factor after cracking through thickness. Using this model, he crack propagation behavior, crack-opening displacement and crack shape change of surface-cracked smooth specimens and surface-cracked specimens with a stress concentration were evaluated quantitatively. The present study was also done to investigate the fatigue crack propagation behavior of surface cracks subjected to combined tensile and bending stress. Estimation of fatigue :rack growth was done using the Newman-Raju formula before through thickness, and using formula (7) and (8) after through thickness. Crack length a_T at just through thickness increases with increasing a bending stress. Calculated fatigue crack shape showed very good agreement with )experimental one. It was also found that particular crack growth behavior and change in crack shape after cracking through thickness can be explained quantitatively using the K value based on Eqs. (7) and (8).

著者

安藤 柱 横浜国立大学工学研究院
安藤 柱 横浜国立大学
小倉 信和 横浜国立大学工学部
松井 健太郎 横浜国立大学大学院
南 起祐 韓国釜慶大
小倉 信和 横浜国立大学
南 起祐 横浜国立大学大学院

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