The Influence of Stiffness of Elastic Restraint in a Damaged Regular System on Its Resonant Vibration.

The paper summarizes the findings of a study of the influence of stiffness parameters of an elastic restraint in a damaged regular system consisting of two duplicate elements and modeling a two-blade assembly, on the generation of vibration of the system under fundamental resonance. A discrete dual-mass model whose vibration is described by a nonlinear set of differential equations of second order has been chosen as a design model of the structurally regular system under consideration. Numerical investigations have been performed using the Runge-Kutta method to solve a nonlinear set of differential equations and the fast Fourier transform method to process the solutions obtained. The dependences of the resonant frequency ratios and resonant amplitude ratios of the first-harmonic vibration on the damage parameter have been derived for the discrete model of the regular system in inphase and antiphase modes, with different parameters of the elastic restraint for the damaged subsystem and for the intact one. It is demonstrated that with a preset value of the damage parameter the frequencies of the inphase and antiphase modes grow with increasing coefficient of the elastic restraint of the subsystems. This influence is the most significant in the case of the antiphase mode of vibration of the subsystems. The elastic restraint coefficient has also a substantial effect on the level of resonant amplitudes of the first-harmonic vibration for the regular-system model under study. It has been found out that as the elastic restraint coefficient grows the resonant amplitude of the intact subsystem increases under the inphase-mode vibration and decreases under the antiphase one. The values of the resonant amplitudes of vibration of the damaged subsystem are influenced by the coefficient to a lesser extent. The maximum value of the resonant amplitudes of vibration of the damaged subsystem is almost independent of the elastic restraint coefficient. [ABSTRACT FROM AUTHOR]