Dynamics of Phononic Materials and Structures: Historical Origins, Recent Progress, and Future Outlook

Recent advances in nonlinear passive vibration isolators

A study of a nonlinear vibration isolator with a quasi-zero stiffness characteristic

Force and displacement transmissibility of a nonlinear isolator with high-static-low-dynamic-stiffness

On the force transmissibility of a vibration isolator with quasi-zero stiffness

Instability Due to Simultaneous Time Variation in Damping and Spring Constants

The non-stationary response in vibrating systems with power-law damping, subjected to sweep tests is considered. Using the method of averaging, it is shown that the bifurcation delay persists in all forms of power-law damping, viz., Coulomb, orifice and cubic damping models. Experimental investigations on a ‘soft’ type of isolator confirm the existence of delay in the jump phenomenon. These results also indicate that the softening nature of non-linearity can be profitably employed in the design of isolators and vehicle suspensions.

Sweep Tests on Vibrating systems with Power-Law Damping

Free out-of-plane vibration of circular rings on identical equi-spaced elastic supports

Natural frequencies of a shaft with periodically placed rotors and bearings

This paper presents a study on the effect of nonlinearities of an elastomeric bearing on isolated lag dynamics and coupled rotor/fuselage ground resonance stability of an idealized bearingless rotor blade. The rotor blade is modeled as an elastic beam with a nonlinear elastomer and a rigid torque tube. First, amplitudedependent natural frequency of the blade in lag mode is analyzed using numerical perturbation technique. Then the problem of amplitudedependent stability of the coupled rotor/fuselage system under ground resonance condition is investigated. The stability of the system is analyzed by two approaches, namely, 1) by eigenanalysis of the linearized equations and 2) by response of the nonlinear system to an initial disturbance by time integration. The results of the eigenanalysis indicate that the effect of amplitude seems to be more dominant on the progressive lag mode damping than on regressive lag mode damping. It is also observed that so far as the stability in ground resonance is concerned there exist optimum locations for the attachment of both the elastomer and torque tube. Results of the time-domain analysis of the nonlinear equations indicate clearly that the stability of the system is dependent on the magnitude of initial disturbance.

Influence of nonlinear elastomer on isolated lag dynamics and rotor/fuselage aeromechanical stability

A.K. Mallik

Papers

Instability Due to Simultaneous Time Variation in Damping and Spring Constants

Sweep Tests on Vibrating systems with Power-Law Damping

Free out-of-plane vibration of circular rings on identical equi-spaced elastic supports

Natural frequencies of a shaft with periodically placed rotors and bearings

Influence of nonlinear elastomer on isolated lag dynamics and rotor/fuselage aeromechanical stability