号数 ばね論文集４９号（２００４年）
ページ数 pp.35-75
種類 委員会報告
論文名 コイルばね解析法の研究委員会報告
Title Report of Research Committee on the Analysis of Helical Spring
著者 コイルばね解析法の研究委員会
Author Research Committee on the Analysis of Helical Spring
抄録 　近年，ばね材料の高強度化に伴い初期ピッチ角が大きくなるにつれ，懸架コイルばねではWahlの応力修正係数の精度を上げたいという声を聞くようになった．
このような背景のもと本委員会は以下の活動を行った．
1) 従来のコイルばね特性式の前提条件の明確化と適用限界の把握
a) 修正係数に関する諸式の導出過程を３つに大別し，各修正式の導出前提条件を明らかにすると同時に数値比較を行った．
b) DIN規格で採用されているBergstrasserの式とWahlの式を比較し，両式に対する見解を示した．
c) 初期ピッチ角を考慮した修正式に関し，修正係数線図をまとめた．
2) 有限要素法による応力及びたわみの修正係数算出
a) 1/4巻曲がり梁を対象にソリッド要素を用いた線形FEM解析を行い，応力修正式の精度を検証した．
ｂ) 有効巻部一巻を対象にピッチ角を考慮した非線形FEM解析をソリッド要素を用いて行い，ピッチ角の影響を検討した．
c) 実験計画法とFEM解析を用いて応力，たわみの修正係数推定式を求め，修正係数線図を作成した．
3) FEM解析を行う場合のモデル化指針の提示
a) 実際のコイルばね形状に基づき梁要素を用いたFEM解析を行った．実測と比較することにより，梁要素を用いる場合の注意点を示した．
b) 梁要素を用いた場合の応力修正係数の傾向に関し考察した．またコイル座との接触条件に関する見解を示した．
Abstract  The demand on more accurate Wahl's stress correction factor for a suspension coil spring is growing stronger as the initial pitch angle becomes larger with the strengthened spring material in recent years.
　This research committee performed the following activities under such circumstances.
1) Clarification of the precondition of the conventional coil spring characteristic formula, and comprehension of an application limit ;
a) Numerical analysis comparison was executed on three patterns of the derivation process of correction factor formulas after clarifying the derivation precondition of the each formula. A.M.Wahl, A.Rover, J.K.Wood, E.Honegger, O.Gohner, P.Henrici, C.J.Ancker & J.N.Goodier, M.Bergstrasser, D.G.Sopwith.
b) The formula of Bergstrasser which is adopted in the DIN standard and the formula of Wahl were compared.
c) The correction factor diagram was summarized on the formula which takes the effect of the initial pitch angle into account.
2) Calculation of the stress and deflection correction factor by FEA ;
a) Linear FEA for a 1/4 circle beam was executed using the solid element, and the accuracy of a stress correction factor formula was verified.
b) Nonlinear FEA for one turn of active coil with different pitch angles were executed using the solid element, and the influence of a pitch angle was investigated..
c) The presumed correction factor formula of stress and deflection was derived using Design of Experiments and FEA, and the correction factor diagram was created.
3) Suggestion of better FEA modeling ;
a) FEA by the beam element was executed on an actual coil spring, and the essential points of the beam element　FEA were proposed by comparing with experimental results.
b) The tendency of the stress correction factor derived from the beam element FEA was studied. Moreover, end turn contact conditions with a coil seat was examined.
著者の所属  
Belonging  
Key Words Helical spring, Stress correction factor, Deflection correction factor, Maximum shear stress, Maximum principal stress, FEM analysis