Research and application of random vibration fatigue analysis method for welded structures
In the service process,welded structures often bear complex random dynamic load.When the dynamic load fre-quency is close to the natural modal frequency of the structure,fatigue failure may occur in the joint,at this point the tradi-tional fatigue analysis method of uniaxial static load is no longer applicable.A multi-axis random vibration fatigue analysis method for welded structures was presented.In this method,the time-domain excitation signals were transformed into self-spectrum and cross-spectrum,the self-spectrum and cross-spectrum including normal stress and shear stress was obtained by combining modal decomposition and structural stress method,and gets the power spectrum of equivalent structural stress was got based on PDMR principle.The structural damage and vibration fatigue life were calculated by using the Dir-lik model.At the same time,a high-speed freight car was taken as an example to analyze the fatigue life,and the timeliness and accuracy of fatigue life prediction of welded structures were verified.
welded structurerandom vibrationfatigue failuretime domainfrequency domainfatigue life