Nonlinear damping identification in rotors using wavelet transform

• Envelope of the signal is extracted by wavelets to identify the nonlinearities in damping.
• Two different nonlinear damping models are studied using the proposed approach.
• Krylov–Bogobliubov method is used to obtain the analytical solution.
• Polynomial type nonlinear damping in rotors estimated using the method.
• Application of the proposed technique to experimental data is presented.

Estimation of nonlinear damping in rotor bearing systems using continuous wavelet transform based approach is proposed. Krylov–Bogobliubov method is used to obtain the approximate analytical solution for the nonlinear equation of motion of the rotor-bearing system. The envelope of the free vibration signal is extracted using the wavelet based approach to identify the nonlinearities in damping. Two different nonlinear damping models are studied using the proposed approach. Two examples are illustrated as coupled and uncoupled versions of equation of motion of a rotor-bearing system including nonlinear viscous external and internal damping. The performance of the method is tested on signals acquired from experiments and found successful.