Study on Vibration Suppression of Multi-Degree-of-Freedom System with Parametric Excitation

本研究的目的是开发一种被动减振器，使多自由度系统的振动抑制成为可能，这种被动减振器被称为参数激励动态减振器或自参数减振器。当将动态减振器的一个固有频率调整到主系统固有频率的一半时，该动态减振器在主系统谐振频率附近产生抑振。动力吸收器的钟摆只在主系统的共振频率周围振动，除了共振频率外不振动。调整后的动力吸收器为第一共振、第二共振等，可以抑制相应共振的振幅，而不干扰其他共振的动力吸收器，因为它只在共振周围振动。为了扩大应用范围，研制了一种包括旋转弹簧和阻尼器的摆式动力减振器。重力振动钟摆由于振动方向和钟摆尺寸的限制，对球面的应用有一定的限制。研究了当摆的支撑点处于振动状态时，带旋转弹簧和阻尼器的摆的参数共振，表明该摆可以用作参数激励动力减振器。在此基础上对三自由度主系统的一共振和二共振进行了实验控制。实验中，固有频率为主系统第一阶固有频率一半的动态吸振器降低了主系统第一阶共振峰值，频率为第二阶固有频率一半的动态吸振器也降低了第二阶共振峰值。讨论了抑制效果和摆态。得出的结论是，每个动力阻尼器只有在相应的共振附近才会起作用，并且主系统的振动变小。因此，所提出的参数激励动力吸振器可以有效地抑制多自由度系统的振动。少

A purpose of this study is to develop a passive absorber which makes it possible to suppress vibration of multi-degree-of-freedom systems using pendulum type dynamic absorbers which is called a parametric excitation dynamic absorber or an autoparametric vibration absorber. Such a dynamic absorber generates vibration suppression near resonance frequency of the main system when a natural frequency of the dynamic absorber is adjusted to half of natural frequency of the main system. A pendulum of the dynamic absorber vibrates only around resonance frequency of the main system and does not vibrate except the resonance frequency. The adjusted dynamic absorber to 1st resonance, 2nd resonance, etc can suppress amplitude of the corresponding resonance and does not disturb the dynamic absorbers for other resonances because it vibrates around only resonance. A pendulum type dynamic absorber which includes a rotational spring and damper has been developed in order to expand a sphere of the applica … More tion. Pendulums vibrated by the gravity have restriction for a sphere of the application because of having limitation of vibrating direction and the pendulum size. Parametric resonance of the pendulum with a rotational spring and damper is investigated when a support point of the pendulum is vibratory, and it is shown that its pendulum can be used for the parametric excitation dynamic absorber.Then 1st and 2nd resonances of three-degree-of-freedom main system have been experimentally controlled by the dynamic absorber. The dynamic absorber with natural frequency equal to half of the 1st natural frequency of the main system reduces a peak of 1st resonance of the main system and the dynamic absorber with the frequency equal to half of the 2nd natural frequency also reduces a peak of 2nd resonance in the experiment. The suppression effect and the pendulum behavior are discussed. It is concluded that each dynamic damper becomes active only near the corresponding resonance and the main system vibration becomes small. Therefore the proposed parametric excitation dynamic absorbers can suppress vibration of multi-degree-of-freedom system. Less