Noble estimation procedure of fatigue crack growth under in-plane biaxial or superimposed stress conditions

2017 Fiscal Year Final Research Report

• Project/Area Number: 26249136
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Naval and maritime engineering
• Research Institution: Kyushu University
• Principal Investigator: GOTOH Koji 九州大学, 工学研究院, 教授 (60274487)
• Co-Investigator(Kenkyū-buntansha): 丹羽 敏男 国立研究開発法人海上・港湾・航空技術研究所, その他部局等, 研究員 (10208267)
• Co-Investigator(Renkei-kenkyūsha): ANAI Yosuke 国立研究開発法人海上・港湾・航空技術研究所, その他部局等, 研究員 (60470051)
• Project Period (FY): 2014-04-01 – 2018-03-31
• Keywords: 疲労 / 破壊力学 / 船舶工学 / 機械材料・材料力学

Outline of Final Research Achievements

Although the fatigue strength evaluation for ships and offshore structures is performed in consideration of external force induced by sea state, it has been pointed out that the influence of superimposed high-frequency elastic vibration components should be considered. However, the conventional fatigue strength evaluation procedure gives a safe side evaluation results. Furthermore, the fatigue strength is evaluated based on the test results under uniaxial cyclic load condition, although the actual structure is exposed to the biaxial or multiaxial with different phase differences.
In this research, the following two research subjects were conducted. (1) Estimation method of fatigue crack propagation under superimposed stress history condition, (2) Estimation method of the growth behavior of surface crack under in-plane biaxial cyclic stress history with phase difference. We established a method to estimate fatigue crack growth history well under these complicated load conditions.

Free Research Field

溶接構造物の疲労及び破壊強度評価