Fatigue analysis in case of random vibration base excitation
Övrigt - Research report 2018:04, 2018
Components in mechanical systems often have requirement specifications with respect to material fatigue. This calls for fatigue analyses in order to ensure sufficient operational lives. Doing this numerically, in the time-domain, is often computationally heavy, due to long time history inputs. Hence, it would be beneficial to carry out numerical analyses in the frequency domain instead. The purpose of this study is to establish an understanding for how numerical methods can be used to estimate material fatigue in the frequency domain when the load is a stationary random vibration. The results will then be compared with those obtained by well established time-domain analyses of fatigue damage. The results show that, by carrying out numerical fatigue analyses in the frequency domain, only one FE-analysis is required to obtain the transfer functions since it can be used for different kinds of signals. The FE-analysis in the frequency domain is more computationally efficient since it does not require time history inputs. Thus, it is considered more computationally efficient to estimate material fatigue in the frequency domain. However, the frequency domain method is not as accurate as the time domain method, which makes the frequency domain method more useful in early phase development.
Power spectral density