一般尺度法的振动疲劳强化系数分析

在Dirlik模型的基础之上，结合一般尺度法（General scaling law）提出适用于平稳宽带随机过程的疲劳强化系数模型。一般尺度法认为结构在原始载荷和强化后载荷下的应力响应功率谱各阶谱矩成简单的线性关系；与Dirlik宽带疲劳损伤模型结合，便得到适用于平稳宽带随机过程的疲劳强化系数模型。为了验证模型的有效性，分别在原始加速度功率谱和经一般尺度法强化后的加速度功率谱载荷下；对悬臂梁采用雨流计数(Rainflow counting)和Miner损伤准则进行疲劳寿命预测，得到它们的疲劳强化系数，并与疲劳强化系数模型得到的疲劳强化系数进行对比。结果表明：提出的疲劳强化系数模型精度为99.7 %，由此可验证疲劳强化系数模型的有效性。

Analysis of Vibration Fatigue Strength Coefficient Based on General Scaling Law

Based on Dirlik model and combining with the general scaling law, this paper proposes a new model foranalyzing the fatigue strength coefficient, which is suitable to the stationary wide- band random vibration loading. Thegeneral scaling law considers that the spectral moments of different orders of the stress- response power- spectra of thestructure under original loading and strengthened loading have a simple linear relationship. Combination of the spectralmoments with the Dirlik wide-band fatigue damage model can lead to the model of the fatigue strength coefficient for thestationary wide-band random vibration loading. To verify the effectiveness of this model, the rainflow counting method andMiner damage criterion are used to predict the fatigue lifespan of a cantilever beam under the original acceleration powerspectralloads. And the result of the fatigue strength coefficient is compared with that calculated by the current model underthe present acceleration power-spectral loads strengthened by general scaling law. It is shown that the accuracy rate of thecurrent model of fatigue strength coefficient proposed here can reach 99.7 %. Thus, the effectiveness of this model isvalidated.