Vibration Fatigue By Spectral | Methods Pdf
The basis of fatigue calculation is the Basquin equation, relating stress amplitude ($S$) to the number of cycles to failure ($N$):
$$ N \cdot S^b = C $$
Where:
Once the PDF of stress ranges $p(S)$ is obtained, damage is calculated using the Palmgren-Miner linear damage rule combined with the material S-N curve (Basquin’s equation: $N S^k = C$).
The expected fatigue life $T$ is calculated as: vibration fatigue by spectral methods pdf
$$E[D] = T \int_0^\infty \fracp(S) \cdot v_pN(S) ds$$
Where $v_p$ is the rate of peaks and $N(S)$ is the number of cycles to failure at stress range $S$. The basis of fatigue calculation is the Basquin
Two dimensionless parameters classify the signal’s “broadbandness”:
[ \alpha_1 = \fracm_1\sqrtm_0 m_2, \quad \alpha_2 = \fracm_2\sqrtm_0 m_4 ] Spectral methods correct for this overestimation
Spectral methods correct for this overestimation.
Several methods have been developed to approximate ( p(S) ) or directly ( E[S^k] ).
