疲労限度以下の応力が累積寿命に及ぼす影響

概要

論文の詳細を見る
In the design of machines the fatigue life of a member under service load is usually calculated on the assumption that Miner's rule can be applied. However according to the results of many program fatigue tests, the linear calculative cycle ratio is not always equal to 1, and the Miner's rule does not take into account the stress cycles under fatigue limit. but the results of fatigue tests, including the stress amplitudes below fatigue limit, obviously show that they influence the cumulative life. This fact is particulary important in the ordinary mechanical structure, because the load spectrum mostly consists of stress amplitude less than the fatigue limit, and the stress amplitude over the fatigue limit is smaller in number. Therefore simple application of Miner's rule is somewhat questionable. The authors have performed the program fatigue tests of carbon steel S35C under the load spectra which have the same pattern of distribution as the frequency diagram measured on the axles of railways. The load spectra are with or without stress amplitude less than fatigue limit to investigate the influence of the stress below the fatigue limit to the cumulative life. From the experimental results a new equation is proposed to estimate the cumulative fatigue life with the effect of the stress amplitude less than the fatigue limit. The total number of cycles of stresses to failure for fluctuating stress can be shown as follows: N_g=N_1{Σ^^m__<i=1>[α_i(σ_i/<σ_1>)_c]+Σ^^r__<p=m+1>[α_p(σ_p/<σ_1>)_<b×c>]} in which n_1, n_2・・・・n/k are the numbers of cycles at stress amplitude σ_1,σ_2,・・・・,σ_k in each program cycle. If n_1+n_2+・・・・+n_k=n_g, then α_1=n_1/n_g, α_2=n_2/n_g,・・・・,α_k=n_k/n_g the value c is decided by the equation Nσ^c=K, K and b is a constant.
社団法人日本材料学会の論文
1968-02-15

疲労限度以下の応力が累積寿命に及ぼす影響

スポンサーリンク

概要

著者

関連論文

スポンサーリンク