The paper proposes a nonlinear dynamic vibration absorber for primary external resonance of system having cubic nonlinearity. A main system with nonlinear spring stiffness and subjected to harmonic excitation is considered. We calculate nonlinear spring stiffness produced by repulsive force of permanent magnets using Coulomb’s law. A damped pendulum system, whose natural frequency is in the neighborhood of twice that of the main system, is nonlinear coupled to the main system by link as a dynamic vibration absorber. This nonlinear dynamic vibration bsorber does not utilize linear coupling to the main system but utilizes nonlinear coupling. Therefore, the attachment of the nonlinear dynamic vibration absorber does not increase the number of degrees of freedom of the main system. Primary resonance amplitude is decreased in the case when pendulum is unlocked and hysteresis of the frequency response curve is disappeared. This means that attachment of dynamic vibration absorber has the same effect that increases directly the damping coefficent of the main system. Experimental results for this type of device are compared with a numerical results obtained from Runge-Kutta method. Comparison of the frequency response curves with and without nonlinear dynamic vibration absorber show validity of the proposed absorber.
439 Piezoelectric Shunt Damping by a Virtual Dynamic Vibration Absorber Utilizing Nonlinear Coupling
