Complex sentence: Mentioned profiles of excitation and response are preferably analyzed in frequency-domain and it is practical to use fatigue-life evaluation methods, that can operate on data in frequency-domain, such as power spectral density or PSD.
Split into simpler sentences: Mentioned profiles of excitation and response are preferably analyzed in frequency-domain. It is then practical to use fatigue-life evaluation methods, that can operate on data in frequency-domain, such as power spectral density or PSD.