Clarification of the rolling fatigue damage mechanism and derivation of a fatigue strength prediction formula of traction drives

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K03827
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 18040:Machine elements and tribology-related
• Research Institution: Muroran Institute of Technology
• Principal Investigator: NARITA Yukihito 室蘭工業大学, 大学院工学研究科, 准教授 (90431519)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 機械要素 / トラクションドライブ / 疲労強度

Outline of Final Research Achievements

To improve the reliability of the rolling fatigue strength design of traction drives, which have potential as a component of reducers that can be adapted to the increased speed of EV motors, we analyzed the fatigue damage mechanism. Observation of the inside of the roller during fatigue testing revealed that the cause of damage, which had previously been thought to be internally initiated damage such as from non-metallic inclusions, was cracks initiating from the roller surface and propagating into the roller's interior. We then applied the Paris law of fracture mechanics and a fatigue life prediction method to the traction drive, and found that the predicted life and fatigue test results were generally in agreement.

Free Research Field

設計工学・機械機能要素・トライボロジー

Academic Significance and Societal Importance of the Research Achievements

トラクションドライブには歯車等の他の伝動要素と比較して高速回転に適するという利点がる．これに破壊力学の疲労寿命予測式を適用した例は見られず，結果もおおむね一致したことは，良い成果と言える．ただし，精度向上の余地はあり，また，介在物がき裂進展速度に及ぼす影響も未解明である．これらをさらに解決出来れば，トラクションドライブの疲労強度設計の信頼性が高まり，EV用モータの高速化に対応可能な減速機の実現が可能となると思われる．