Conclusion
Lifetime of a mechanical system

Statistical analysis is mainly represented by counting methods. Frequency analysis is mainly determined by the study of power spectral density and the extreme response spectrum. The combination of the two analyses allows us to consider the stress under study as a random process. By assimilating a random stress to a random trajectory, we can propose probabilistic models for a number of digital counting methods. These probabilistic models can also incorporate elements of frequency analysis and, more specifically, the power spectral density of the stress under study.