Astudy on modal characteristics of combined rotor shafting under axial preload
LI Weibo1,WANG Weimin1,2,LI Ming3,WANG Wei1,ZHANG Shuai1
1.Beijing Key Laboratory of Health Monitoring Control and Fault Self-recovery for High-end Machinery,
Beijing University of Chemical Technology, Beijing 100029, China;
2.Key Lab of Engine Health Monitoring-Control and Networking, Beijing University of Chemical Technology, Beijing 100029, China;
3.Beijing Aerospace Propulsion Institute, Beijing 100076, China
Abstract:The combined rotor shafting structure is the main structure of rotor systems in aero-space power equipment. The existence of contact surfaces in shafting makes the rotor dynamic characteristics difficult to be grasped, and a design risk arises when rotor working speed margin is involved. Considering the nonlinear connection parameters between different contact surfaces based on the characteristics of single spindle multi components axial preloading structure of combined rotor shafting, a two-step model correction method based on thin-layer elements and zero-length elements modeling was proposed. The nonlinear analysis of static structure based on response surface optimization and the contact analysis of rough surface based on stochastic statistical model were used to identify the material parameters of thin-layer elements and the contact stiffness coefficients of zero-length elements, then the rotor dynamic model was established. According to the structural characteristics of an engine hydrogen-turbopump rotor , a rotor test piece was manufactured, and its free mode was experimentally studied to obtain the effects of different thread pre-tightening states and axial preloads on the first two orders of modal characteristics of the combined rotor shafting. Comparing with the experimental data, the proposed model optimization method can well reflect the variation trend of the first two orders of modal frequencies of the combined rotor shafting under different axial preloads, and the calculation error is less than 1% in the range of linear variation of rotor modal parameters, which verifies the correctness and validity of the method and provides a reference basis for the refined modeling of combined rotor shafting.
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