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The Fatigue Damage Spectrum (FDS) of a vibration is obtained by tracing the fatigue damage experienced by a linear Single Degree of Freedom System (SDOF) according to its natural frequency, for given damping ratio and for a given value of parameter b (this parameter comes from the Basquin law representing the Wöhler curve of the material constituting the structure). Regardless of the vibratory signal studied (sinusoidal vibration, shock, random or composite vibration); the FDS can be obtained directly from the time history signal. The method consists of : *numerically calculating relative response displacement of the mass in relation to its support; *establishing a peak histogram, giving the number ni of peaks according to their amplitude; *using Miner’s damage accumulation law. In the case of stationary random vibration, the Power spectral density (PSD) of the vibration can be directly used for the FDS calculation. ==Note== Vibrations can damage a mechanical system as a result of several processes, among which are: *the exceeding of characteristic instantaneous stress limits (yield stress, ultimate stress etc.); *the damage by fatigue following the application of a large number of cycles. FDS is used according to the second criterion. The first criterion is considered with the ''Extreme response spectrum'' (ERS). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Fatigue damage spectrum」の詳細全文を読む スポンサード リンク
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