Issue 78

F. Veschi et alii, Fracture and Structural Integrity, 78 (2026) 44-73; DOI: 10.3221/IGF-ESIS.78.04

Since most standard SoR specifications feature wideband random noise, Rice's method often operates outside its underlying assumptions, treating the entire process as a narrowband signal and overestimating the Damage Index. Although a cautious estimate is generally desirable, this PDF approach proves to be excessively conservative, rendering the results practically unusable.

Figure 18: Comparison of pseudo-damage estimates under MIL-STD 810 SoR loading. The dashed grey line represents the reference rainflow counting pseudo-damage ( RFC PD ). Percentages above the bars indicate the relative error of each predictive method.

Figure 19: Statistical comparison of the predictive models under MIL-STD 810 SoR loading. The reference RFC probability density function is depicted as a shaded grey histogram in the first panel.

C ONCLUSIONS AND PRACTICAL RECOMMENDATIONS his study presented a comprehensive comparative analysis of spectral methods for estimating fatigue damage under SoR loading conditions, evaluating both the theoretical approach of Rice and the practical Equivalent PSD methods. The performances of these predictive models were systematically benchmarked against exact time-domain calculations, derived from the application of the RFC algorithm over 3600s synthetic time-histories. Assuming a relative T

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