The paper presents a new fatigue damage assessment model defined for the strain energy density parameter. The model is defined for calculations in the frequency domain for the case of narrowband loading. Analytical expressions are derived for the probability density function of peaks, the level crossing spectrum, and for the expected damage that is directly linked to the power spectral density of the strain energy parameter. The paper presents a theoretical proof which shows that the damage obtained for the energy model is equal to the damage obtained for the stress model. A numerical example is used to verify the correctness of the proposed frequency-domain damage estimation formula by comparison with experimental and time-domain fatigue life estimation results for two simulated random time-histories for the case of narrowband and broadband loading. The comparison between experimental and calculation results confirm the very good agreement between frequency and time domain approaches.

本文提出了一种为应变能密度参数定义的新的疲劳损伤评估模型。定义该模型是为了在窄带负载情况下在频域中进行计算。得出了峰的概率密度函数，水平交叉谱以及与应变能参数的功率谱密度直接相关的预期损伤的解析表达式。本文提供了理论证明，表明能量模型获得的损伤等于应力模型获得的损伤。通过与两个模拟随机时间历史在窄带和宽带负载情况下的实验和时域疲劳寿命估计结果进行比较，使用一个数值示例来验证所提出的频域损伤估计公式的正确性。实验和计算结果之间的比较证实了频域和时域方法之间的良好一致性。