抄録
6×7 C/Lワイヤロープ(20,22,24,26mm ∳)が引張り曲げを受けた場合の応力をストレーンゲージ(抵抗線歪計)を以て測定し, なお輪圧張力比および曲げ応力分布について検討した。その結果は次のとおり。(1) 曲げ応力の測定値はISAACHSENの理論値よりかなり小さく, 20 mm ∳で約1/3,26 mm ∳で約2/3であるが, 直径が大きくなるにともない曲げ応力もまた大きくなる。(2) 輪圧張力比について, σ_b≦(σ_t)/2,総応力σの安全率N≧2.0並びに強力安全率N_t≧2.5という条件の下に検討した結果, 輪圧700 kg以下の場合N_t≒3.0が最も適当であることを明らかにした。(3) 輪圧を受けたワイヤロープの曲率半径を測定し, 次式のρに代入して, E_fI_rおよびE_f(曲げ剛さ及び曲げ剛性弾性率)を計算したが, ワイヤロープと等しい断面二次モーメントを有する丸鋼棒のそれらよりも遙かに小さかつた。理論式は次のようである。ρ=2/Q√<E_fI_rT>曲げ応力の分布範囲をこれに関する理論式によつて計算し, 実験値とほとんど等しいことを確かめた。
We measured stress of wire ropes (6×7 C/L, 20,22,24 & 26 mm ∳) in tension and bent by wheel load by means of wire resistance strain gage, and studied the ratio of tension to wheel load and bending stress distribution. The results are as follows;(1) Value of bending stress measured is considerably smaller than theoretical value of ISAACHSEN, that is, that of 20 mm ∳ is about one-third and that of 26 mm ∳ is about two-thirds, and the larger the rope diameter is, the greater the value of bending stress becomes.(2) We studied the ratio of tension to wheel load according to the stress diagrams on conditions that σ_b≦(σ_t)/2,N (safety ratio about σ=σ_t+σ_b)≧2.0 and safety ratio about tension N_t≧2.5 and we made clear that N_t≒3.0 when wheel load is smaller than 700 kg is most suitable.(3) Radius of curvature ρ of the ropes bent by wheel load was measured. Substituting this value for ρ in the formula ρ=2/Q√<E_fI_rT> where E_f : The modulus of elasticity for bending rigidity I_r : Moment of inertia of the rope Q : Wheel load E_f I_r and E_f were calculated and they were far smaller than those of a round steel bar of which moment of inertia is equal to that of the rope.Distributing range of bending stress is calculated by a theoretical formula about this and it was ascertained that almost equal to the experimental value.
