Dynamic Saint-Venant principle for rotor system with undetectable initial crack

摘要

This paper dedicates on the analysis of the initially cracked rotor system and the ratiocination on the reason why the initial crack is undetectable via signal processing method using dynamic Saint-Venant principle (DSVP). A numerical simulation is intensively conducted to justify the theoretical analysis. The conclusion has been obtained that the dynamic resultant of the initial crack force equals to zero in one period and the stress wave excited by the initial crack force will not interfere the lubrication of the supporting bearings when the frequency of the initial crack force preserves to be less than the limited frequency. This conclusion indicates that the undetectable initially cracked rotor system satisfies the criterions of DSVP, and the health monitoring method using ultrasonic wave should be adopted for initial crack diagnosis.