論文
鋼製圧縮コイルばねに見られる擬弾性残留変位の圧縮時間依存性
2019 年 2019 巻 64 号 p. 53-55
詳細
2019 年 2019 巻 64 号 p. 53-55
Although anelasticity is an important phenomenon for spring technology, affecting the size and restoring force of a spring during its operation, its time effect under stress has not been clarified yet. In this study we have evaluated the effects of compression holding time to the anelastic residual displacement of SWP-A or SUS304-WPB steel compression coil springs after unloading. Since free length variation of the coil spring is the summation of the faint twist modification in the steel wire, we can estimate pinning and unpinning phenomena of bowing-out dislocation under pure share strain. In both specimens, recovery of residual displacement showed logarithmic increase with time. The amount of residual displacement in ferrite SWP-A spring linearly increases with compression holding time from 5 to 80 s. It indicates amount of weakly-pinned bowing-out dislocations is increasing during the time of compression with certain pinning sites in ferrite. On the other hand, the amount of residual displacement in austenitic SUS304-WPB spring is small and does not increase significantly with time. It is verified that the time effect of anelastic phenomena in ferrite and austenite steel occurs in quite different way.
