硬鋼の繰返し応力:ひずみ関係およびヒステリシスループ形状に及ぼす履歴の影響

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The effects of strain history both on the cyclic stress-strain relation and on the shape of hysteresis loop have been investigated on annealed S55C by the constant strain amplitude tests with different mean strains and the incremental step tests. The results are summarized as follows: (1) The cyclic stress-strain curves of the constant strain amplitude tests coincide with each other irrespective of the mean strain in the stationary state of fatigue process, or at a half of the fatigue life. They can be written as Δσ=KΔε_p^n, where K=338 and n=0.254, when Δσ is taken as the true stress range and Δε_p as the logarithmic plastic strain range. The cyclic stress-strain relation in the incremental step tests also has a similar trend as above, being represented by the equation Δσ=KΔε_p^n, K=317 and n=0.232, when the stationary state is considered to be at half of the number of blocks to failure. (2) For the constant strain amplitude tests, the shape of hysteresis loop in the stationary state is represented, regardless of mean strain, as (σ^*=K<ε_p^*>^<n^*>, K^*=KΔε_p^<n-n^*> and n^*=0.06Δε_p^<-0.193>, where (σ^* and ε_p^* designate the true stress and the logarithmic plastic strain respectively, with the origin of the coordinates being located at one end of the hysteresis loop. On the other hand, for the incremental step tests, it is written as follows, since n^* is observed to be nearly constant ; σ^*/Δσ= (ε_p^*/Δε_p)^<n^*>, n*=0.114 The equational difference of the shape of hysteresis loops in both cases has to be discussed carefully in view of some variations of the data obtained. However it may be considered very useful to adopt the latter equation for the incremental step tests, since the mechanical behavior of the material is fully defined from three constants of K, n and n^*, which are easily obtained from one specimen.
社団法人日本材料学会の論文
1975-04-15

硬鋼の繰返し応力:ひずみ関係およびヒステリシスループ形状に及ぼす履歴の影響

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