RESPONSE PREDICTION OF FRICTIONALLY CONSTRAINT BLADE SYSTEMS BASED ON A VARIABLE NORMAL LOAD MICROSLIP MODEL

摘要

A discrete microslip friction contact model, which can consider time-dependent/space-related normal load, has been established to investigate the contact kinematics in the contact interfaces between adjacent blade shrouds. The model extends the capability of Csaba's model in dealing with the situation of variant normal load. A Fast Anti-alias Fourier transform (FAFT) is introduced to the alternating frequency/time domain method (AFT) to improve the accuracy of spectrum analysis and extend analysis spectrum range. The developed friction model and the modified AFT are applied to calculate nonlinear vibration for a simplified shrouded blade, and the effect of parameters on resonant frequency and amplitude of shrouded blade are investigated and discussed. Comparing with existing variable normal load macroslip model, the model proposed here has the mathematically tractable characteristic and can be easily used. Combining with the AFT method, it is suitable for the analysis of complex system with multiple variables and degrees of freedom, and it can meet the engineering need.