다중 주파수를 위한 동적 흡진기 개발

Abstract

Mechanical and building design should consider vibration problem. Because the natural frequencies of the structure and the waves due to the external force resonate, there is a problem that the structure shakes a lot. Among the methods to solve the resonance problem with the natural frequency, a method using the dynamic vibration absorber was studied. The dynamic vibration absorber consists of mass and stiffness. If the natural frequencies of the host structure and the dynamic vibration absorber are matched, the dynamic vibration absorber receives the vibration of the host structure and reduces the amplitude of the natural frequency. Since the dynamic vibration absorber matches only one natural frequency of the natural frequency of the structure, the efficiency is lowered. The dynamic vibration absorber, which reduces only one natural frequency, has been studied for a long time and is being reduced efficiently. And dynamic vibration absorber has been developed to be used in industrial field. In addition, design using optimization was carried out. The development of a multi frequency vibration absorber that reduces multiple natural frequencies has been studied. Simulations and experiments were conducted to confirm vibration absorption. The experimental method was carried out in two ways to analyze the effect of the natural frequency amplitude of the structure on the Eigen mode shape of the dynamic vibration absorber. The first method is to attach the multi frequency vibration absorber in the vertical direction to the structure, and the second method attaches the multi frequency vibration absorber in the parallel direction to the structure. Simulations and experiments confirmed that the multi frequency vibration absorber attached in the vertical direction lowered the 1st, 2nd and 3rd natural frequency. But the multi- frequencies vibration absorber attached in parallel has lowered the 1st natural frequency and 2nd natural frequency. It is analyzed that the vibration at the 2nd natural frequency is not lowered by the Eigen mode shape of the multi frequency vibration absorber. Because the mode shape of the 2nd natural frequency is mode shape in which both sides move in different directions in a torsion mode. Therefore, it is an effective way to reduce the natural frequency amplitude at the same time by attaching it to the structure in the vertical direction. In this paper, we have developed a multi frequency vibration absorber that reduces the natural frequency amplitude at the same time.