Fatigue damage spectrum method of combining spectra
MIL-STD-810H, Environmental Engineering Considerations and Laboratory Tests
Last Updated 29 Oct 2026
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2 tables appear under this heading.
1. PDF page 488
| DP(fn) | Damage index as a function of system natural frequency |
| fn | System natural frequency (variable), Hz |
| T | Exposure time in environment, seconds |
| G(fn) | ASD for a given environment, g²/Hz |
| ζ | Damping ratio of system at dominant natural frequency expressed as a decimal |
| b | Fatigue curve slope value when computed as a linear fit in a log-log domain. |
2. PDF page 488
| where: |
|---|
| DPt(fn) | = Total damage index spectrum. |
| DPi(fn) | = Individual environment damage spectra as defined in equation C.1. |