Construction of a new crack growth suppression method by paste method and plasma method for long cracks

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K13664
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 18010:Mechanics of materials and materials-related
• Research Institution: Kurume National College of Technology
• Principal Investigator: Sasaki Daisuke 久留米工業高等専門学校, 材料システム工学科, 助教 (50772498)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 疲労破壊 / き裂進展 / 焼結物 / くさび効果 / 補修 / パルス通電 / 微粒子 / 大型構造物

Outline of Final Research Achievements

In this study, we have developed a repair method "plasma particle method" by pulsed energization sintering and powder particles. In addition to, we have researched the fatigue life extension effect and fatigue fracture behavior. The following 6 results were obtained. 1 A sintered product of fine particles have been formed in the simulated cracks. 2 It was confirmed that the fatigue crack growth rate was decreased. 3 It was confirmed that this repair method did not affect the crystal grain size. 4 The hardness of the crack tip was slightly reduced due to the heat of repair. 5 When the crack growth rate increases, the brittle fracture surface rate increases.6 Finite element method suggests that the plastic region at the crack tip becomes smaller due to the sintered product.

Free Research Field

材料強度

Academic Significance and Societal Importance of the Research Achievements

建設後50年経過する構造物において，補修工事の猶予時間を設けるため，簡易補修方法の開発が望まれている．しかし，有用な既存の補修方法でも10cm程度の開いた疲労き裂補修が残された課題となっている．本研究では，大きく開いた疲労き裂の補修に成功し，き裂進展速度を減速させ，寿命を延命することに成功した．社会的意義は，老朽化が進んだ大型構造物の補修工事の猶予時間を設けることができる点にある．学術的意義は，き裂進展抑制メカニズムに新たに焼結物によるくさび効果を加えた点にある．