Stay bolt assembly tightness identification method for dismountable disk-and-drum rotor of aero-engine

Aiming at a major factor affecting dismountable disk-and-drum rotor vibration characteristic of an aero-engine by stay bolt assembly tightness along the circumferential wheel disks, a stay bolt assembly tightness identification method was proposed. By means of vibration excitation test for dismountable disk-and-drum rotor, relative energy feature was extracted from lifting wavelet package decomposition reconstruction signal and a definition of stay bolt assembly tightness entropy was defined by mapping relative energy feature into stay bolt assembly tightness identification space. Three assembly tightness conditions of stay bolt from looseness to tightness were studied in test. The results showed that assembling tightness entropy had consistent monotone decrease rule. The assembly tightness of a dismountable disk-and-drum rotor of an aero-engine commissioned in field was tested and the assembly tightness of stay bolt was identified as degradation and looseness conditions.