Vibration is closely related to structural dynamics, and the study of random vibration fatigue loads is typically conducted in the frequency domain. In this study, various frequency domain methods were employed to predict the random vibration fatigue life of DZ125L directionally solidified superalloy under different vibration signal intensities. Experimental analysis was used to examine the fatigue life and random vibration response of DZ125L alloy specimens under different vibration signal intensities. The S-N curve derived from sinusoidal vibration tests was used to replace the traditional S-N curve obtained from tension-compression tests in random vibration fatigue analysis, leading to improved life prediction accuracy. Additionally, an intensity function $f\left(\xi \right)$ was established using the spectral width parameters ${\alpha }_1$ and ${\alpha }_2$ of the random process and the vibration signal intensity $\xi$, which was used to modify the traditional Rayleigh method. A new vibration fatigue life prediction model based on frequency domain method is obtained. The results indicate that the intensity function $f\left(\xi \right)$ emphasizes the elastic or plastic stage of the specimen during the random process, leading to highly accurate life prediction values using the Modified Rayleigh method across different vibration signal intensities, with all prediction points are within 1.5 times the scatter band.

振动与结构动力学密切相关，随机振动疲劳载荷的研究通常在频域进行。本研究采用多种频域方法预测DZ125L定向凝固高温合金在不同振动信号强度下的随机振动疲劳寿命。通过实验分析考察了DZ125L合金试件在不同振动信号强度下的疲劳寿命和随机振动响应。在随机振动疲劳分析中，采用正弦振动试验推导的SN曲线替代了传统拉压试验推导的SN曲线，提高了寿命预测精度。此外，强度函数$F\left(\xi \right)$是使用光谱宽度参数建立的${\alpha }_{\mathrm{1个}}$和${\alpha }_{\mathrm{2个}}$随机过程和振动信号强度$\xi$，用于修改传统的瑞利方法。得到了一种新的基于频域法的振动疲劳寿命预测模型。结果表明强度函数$F\left(\xi \right)$强调随机过程中试件的弹性或塑性阶段，在不同的振动信号强度下使用修正瑞利法得到高精度的寿命预测值，所有预测点都在散布带的 1.5 倍以内。