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通过对实验结果的分析,发现了零件在低温时,疲劳曲线会出现转折点,以此点为界曲线分为左右意义不同的两支;在中等温度时,并不出现这种转折,随着循环次数的累加,允许承受的应力幅值迅速降低;高温时这种转折点反而明显的现象;分析了高温时出现这种转折的原因;利用对极限应力曲面和极限应力曲线的分析,给出了高温下机械零件承受持久交变应力时的安全系数的确定公式;指出了相当静应力σeτ和相当应力σ’eτ的计算方法;得出了高温时,零件在叠加于静应力上的交变应力作用下,蠕变是决定疲劳极限的重要因素和蠕变速度的提高应视作是疲劳损伤出现的结论。
Through the analysis of the experimental results, it is found that when the parts are at low temperature, the turning point of the fatigue curve will appear, and the curve of this point will be divided into two branches with different meanings. At medium temperature, this transition does not occur. The cumulative number of times allowed to withstand the rapid reduction of stress amplitude; this turning point at high temperatures but the obvious phenomenon; analysis of high temperature occurs when the turning point; the use of the ultimate stress curve and the ultimate stress curve analysis gives the high temperature Under the constant mechanical stress, under the constant alternating stress to determine the safety factor of the formula; pointed out the equivalent static stress σeτ and equivalent stress σ’eτ of the calculation method; obtained at high temperatures, the parts superimposed on the static stress superimposed by the role of alternating stress , Creep is an important factor that determines the fatigue limit and the improvement of creep speed should be regarded as the conclusion of fatigue damage.