Vibration quenching of machines and structures by nonlinear passive dynamic absorbers

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I.Research on dynamic absorbers to quench self-excited vibration. Dynamic absorber with viscous damping, that with Coulomb friction and impact damper are dealt with.i) The amplitude of self-excited vibration becomes zero by using strong viscous damping in dynamic absorber with viscous damping.ii) There exist optimum Coulomb friction, optimum clearance and coefficient of restitution to quench self-excited vibrations by dynamic absorber with Coulomb friction and impact damper respectively.II.Research on vibration quenching and electricity generating device. This device is composed of generator and Hula-Hoop which is fixed on the shaft of generator. This device quenches main system and generate electricity. Followings are found theoretically and experimentally.i) This device quenched the resonance of one-degree-of-freedom forced vibration and its amplitude was decreased to approximately 1/3. Moreover electricity was generatedii) The resonance amplitude was decreased to approximately 1/5 by hybridizing this device and dynamic absorber.iii) The amplitude of self-excited vibration was decreased to approximately 1/3 and the state of vibration was chaos.iv) The experimental results agreed very well qualitatively with those from the theoretical analysis.III.Research on nonlinear dynamic absorber with piecewise linear restoring characteristic. It was found that the vibration quenching region was widened twice as large as the case of linear dynamic absorber. Moreover it was supposed that to design this absorber was easier than to design linear one.