Effect of laser pulse duration on residual stress generation and fatigue strength in laser peening

2022 Fiscal Year Final Research Report

• Project/Area Number: 19H02228
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 22020:Structure engineering and earthquake engineering-related
• Research Institution: Kindai University
• Principal Investigator: Yoshihiro SAKINO 近畿大学, 工学部, 教授 (80273712)
• Co-Investigator(Kenkyū-buntansha): 岡本 康寛 岡山大学, 自然科学学域, 准教授 (40304331)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: レーザピーニング / 残留応力 / 疲労 / 突合せ溶接 / 構造用鋼 / 高張力鋼 / パルス幅

Outline of Final Research Achievements

The laser peening conditions for structural steel using ultra-small laser with different pulse duration from previous studies were selected. The fatigue strength improvement was confirmed by the fatigue experiments of the welded specimens subjected to laser peening under the selected conditions. Moreover, effects of laser peening conditions including laser pulse duration on the residual stress generated by laser peening were investigated. The relationship between residual stress distribution and fatigue strength was also considered.
Pulse duration: Irradiation time of one pulse of laser, Laser peening: Process of tapping the surface of a metal material using pulsed laser, Residual stress: Stresses that remain in an object even in the absence of external loads or thermal gradients, Fatigue strength: Strength against repeated loads.

Free Research Field

溶接構造

Academic Significance and Societal Importance of the Research Achievements

新たに開発された超小型マイクロチップレーザを用いたレーザピーニングを、実際の橋梁等の大型鋼構造物に適用するための基礎的検討と試験体レベルでの効果確認を行った。このレーザピーニング装置が実用化されれば、現場でレーザピーニングが適用できるようになり、既存の大型鋼構造物の延命が可能となる。また、レーザピーニングの施工条件が生成される残留応力に及ぼす影響を明らかにすることで、施工条件の条件設定が容易となる。さらに、残留応力分布と疲労強度の関係が明らかになれば、残留応力をどのようにコントロールすれば疲労強度向上に効果的かが明らかとなる。