| 号数 | ばね論文集51号（2006年） |
| ページ数 | pp.9-15 |
| 種類 | 論文 |
| 論文名 | ばね鋼の切欠き疲労強度予測 |
| Title | Fatigue Strength Predictions of Notched Specimens of Spring Steel |
| 著者 | 高橋文雄1) 丹下 彰1) 小野芳樹1) 安藤 柱2) |
| Author | Fumio TAKAHASHI 1) Akira TANGE 1) Yoshiki ONO 1) Kotoji ANDO 2) |
| 抄録 | "この論文はばね鋼切欠き材の疲労限度と疲労寿命の予測についての研究である．Haddadの疲労限度式に硬さおよび応力比依存性を追加拡張した疲労限度予測式と疲労き裂伝播式の妥当性を疲労試験結果との比較によって確認した．用いた試験片は放電加工による半円状表面切欠きを有する，脱炭なし材，脱炭あり材，ショットピーニングあり材である．結果を以下にまとめる．
(1) 脱炭なし材では，疲労限度線は折損データのわずかに下側に位置し，安全側の評価を示すことから，実用性があると考えられる．
(2) 脱炭あり材では，疲労限度線は折損データと未折損データの境界に位置し，実用性が高いことが確認された．
(3) ショットピーニング材では，疲労限度線は安全側の評価を示し，実用性のあることが確認された．
(4) 疲労き裂伝播特性の比較において，計算結果のda/dN-��K線図は，実験データと良い一致を示した．
(5) S-N線図上で，計算による時間寿命は脱炭なし材の実験データに対し，わずかに短寿命となっている．また，計算による時間寿命は脱炭あり材の実験結果と良好な一致を示した．従って，本き裂伝播式は実用性があるものと考えられる" |
| Abstract | This paper presents the study on fatigue strength and fatigue life predictions of surface notched specimens of
spring steel. The validity of the fatigue limit prediction and the fatigue crack growth prediction based on
Haddad's equation, where the hardness of material and stress ratio were taken into considerations, were
studied, compared with the experimental results. The specimens with semicircular notch by electrical
discharge machining were prepared. The conditions of tests were without decarburization, with
decarburization and with shot peening. The main results can be summarized below:
（1）The calculated fatigue limits were slightly smaller than the experimental results for the without
decarburization specimens. It can be said that the fatigue limit prediction is evaluated within the safe side
in this case.
（2）The calculated fatigue limits were between the experimental fracture and non-fracture results for the
decarburized specimens. Therefore, the fatigue limit prediction can be said to be effective.
（3）The fatigue limit prediction for the shot peeed specimens was evaluated within the safe side. It can be
said that the prediction is effective.
（4）The calculated fatigue crack growth behavior with da/dN-ΔK diagrams showed good agreements with
experimental results.
（5）The calculated fatigue life was slightly shorter than the experimental fatigue life without decarburization
on the S-N curves. The calculated fatigue life showed good agreements with the experimental results
with decarburization. Therefore, it can be concluded that the fatigue crack growth prediction is very
effective. |
| 著者の所属 | 1)日本発条�蝓。押鵬Ｉ郵駑�大学 |
| Belonging | １）NHK SPRING CO., LTD. ２）Yokohama National University |
| Key Words | Fatigue limit, Fatigue life, Notched specimens, Decarburization, Shot peening |