Study on crack opening/closing behavior of fatigue surface crack and fatigue life priduction

疲劳表面裂纹开闭行为及疲劳寿命研究

• 批准号: 08455478
• 负责人: TOYOSADA Masahiro
• 金额: $ 4.99万
• 依托单位: KYUSHU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08455478/
• 关键词: fatigue life; fatigue surface crack; crack opening; closing behavior; interference effect; laser interference displacement indicator; き裂開閉口; 表面き裂の合体成長; ΔK_<RP>; シミュレーションモデル; レーザ干渉法

It is that a purpose of this study establishes fatigue life assessment method of surface crack emanated from weld toe. The life during plural surface crack usually occupies the major portion of total fatigue life. Therefore it is necessary to establish the estimation method of fatigue propagation life before completion of crack coalescence. A supposed surface crack which exist alone at the notch root and of which K value is the same as K value with considering interference effect from near crack is considered. Then it becames clear that thereis a important law about the change of ratio for the supposed crack with respect to K value which may represent indirectly crack propagation behavior for multiple surface cracks emanated from notch root with welding tensile residual stress field.The measuring system using laser interference displacement indicator was developed for the purpose of obtaining the crack opening/closing behavior. Then problems of this system were investigated and some improved points were indicated.

本研究的目的就是建立焊趾表面裂纹疲劳寿命评估方法。多个表面裂纹期间的寿命通常占总疲劳寿命的主要部分。因此有必要建立裂纹合并完成前疲劳扩展寿命的估算方法。考虑假设表面裂纹单独存在于缺口根部，且其K值与考虑近裂纹干扰影响的K值相同。由此可见，假定裂纹相对于K值的比例变化存在一个重要规律，可以间接表征在焊接残余拉应力场下从缺口根部产生的多个表面裂纹的裂纹扩展行为。激光测量系统开发干涉位移指示器的目的是为了获得裂纹的张开/闭合行为。然后分析了该系统存在的问题并指出了一些改进的地方。

项目成果

豊貞雅宏 他: "回し溶接止端部から発生・天播する微視・微小表面き裂のアスペクト比変化に関する研究" 西部造船会会報. 第95号. 171-180 (1998)

Masahiro Toyosada 等人：“对车削焊缝趾部产生和传播的微观和微观表面裂纹的纵横比变化的研究”，西方造船师学会公告，第 95 期。171-180 (1998)。