| 号数 | ばね論文集 62 号（ 2017 年） |
| ページ数 | pp.37-47 |
| 種類 | 論文 |
| 論文名 | 引張りコイルばね中の表面き裂の応力拡大係数のFEM 解析 |
| Title | FEM Analyses of Stress Intensity Factors for Surface Cracks in Tension Coil Springs |
| 著者 | 中曽根祐司1)，村主和憲1) |
| Author | Yuji NAKASONE1), Kazunori MURANUSHI1) |
| 抄録 | 本研究では，引張コイルばねの素線表面上の半だ円表面き裂の3次元FEM解析を実施し，3種類のモードの応力拡大係数の修正係数Fi (i=I, II and III)に及ぼす各種のばねパラメータの影響を調べた．本研究で対象としたパラメータは，き裂傾斜角, 素線断面におけるき裂位置，正規化したき裂表面長 c/r, き裂の縦横比a/c及びき裂指数s=R/rである．ただし，cはき裂表面長の半分，rは素線径，aはき裂深さである．モードI修正係数，すなわち正規化したモードI応力拡大係数FIは，今回解析したすべての場合について他の2種類のモードの修正係数よりも大きな値をとった．また，そのFI値に最も強く影響を及ぼしたパラメータはき裂縦横比a/cであり，a/c=4 のとき=0°となる素線表面近傍において最大値FI≒2.75となった．これに対して，他の2種類のモードの修正係数FII及びFIIIに最も強く影響を及ぼしたパラメータはき裂傾斜角であり，FIIの最大値は，=90°のとき=180°となる素線表面近傍において約1.3，FIIIの最大値は，=90°のとき=90°となるき裂最深点において約0.59となった． |
| Abstract | In this study, 3D finite element analyses have been made on the stress intensity factors for semi-elliptical surface cracks on the wire surface of a tension coil spring in order to investigate the effects of spring parameters on the correction factors, Fi (i=I, II and III) for the three modes of the stress intensity factors. The parameters selected for the present analyses are crack inclination angle θ, crack position on wire surface, normalized half crack surface length c/r, crack aspect ratio a/c and spring index s=R/ r where c is the half crack surface length, r the wire radius, a the crack depth and R the coil radius of the spring. The mode I correction factor, or the normalized mode I stress intensity factor FI was found dominant over the correction factors for the other two modes in all the cases investigated. The most influential parameter for FI was the crack aspect ratio a/c, and the largest FI value was calculated as approximately 2.75 for a/c=4 near wire surface, i.e.,φ=0°. The most influential parameter for the other correction factors FII and FIII was the crack inclination angle θ. The correction factors FII and FIII were revealed to take on smaller maximum values than FI: i.e., the maximum absolute value of FII was found approximately 1.3 for θ=0° and 90°near wire surface (φ=0° and 180°), and that of FIII approximately 0.59 for θ=0° and 90°at the deepest point of the crack (φ=90°). |
| 著者の所属 | 1)東京理科大学 |
| Belonging | 1)Tokyo University of Science |
| Key Words | Coil, Tension, Spring, Surface Cracks, Stress Intensity Factor, Mixed Mode, Finite Element Method |