Particle Damping with Granular Materials for Multi Degree of Freedom System

Abstract

Abstract.A particle damper consists of a bed of granular materials moving in cavities within a multi degree-of-freedom (MDOF) structure. This paper deals with the damping effects on forced vibrations of a MDOF structure provided with the vertical particle dampers. In the analysis, the particle bed is assumed to be a single mass, and the collisions between the granules and the cavities are completely inelastic, i.e., all energy dissipation mechanisms are wrapped into zero coefficient of restitution. To predict the particle damping effect, equations of motion are developed in terms of equivalent single degree-of-freedom (SDOF) system and damper mass with use made of modal approach. In this report, the periodic vibration model comprising sustained contact on or separation of the damper mass from vibrating structure is developed. A digital model is also formulated to simulate the damped motion of the physical system, taking account of all vibration modes. Numerical and experimental studies are made of the damping performance of plural dampers located at selected positions throughout a 3MDOF system. The experimental results confirm numerical prediction that collision between granules and structures is completely inelastic as the contributing mechanism of damping in the vertical vibration. It is found that particle dampers with properly selected mass ratios and clearances effectively suppress the resonance peaks over a wide frequency range.

Examination of Particle Behavior in Container on Multi-Particle Collision Damper

“…Hereafter, we focus on the contact of particle i with particle j, as shown in Figure 2. Denoting the spring constants in the n, s and b directions as kjn, kjs, and kjb(=kjs), respectively, the spring forces ejn, ejs, and ejb, are given as in Equation (4). Denoting the damping coefficients in the n, s, and b directions as Cjn, Cjs, and Cjb(=Cjs), respectively, the damping forces, djn, djs, and djb, are given by Equation (5) [17].…”

“…The "shockless hammer", which is hammer that operates without reaction, is a case of a tool using an impact damper. Another example of a particle damper is a container filled with many spherical particles [4]. There are many references to such a setup within the literature [5][6][7][8][9].…”

Analysis on Vibration Characteristics of Air Film Damping with Open Boundaries

“…However, dry friction damping is merely applicable for low frequency vibration machinery and the constrained layer damping cannot withstand high centrifugal load which means it cannot be applied to highspeed rotor blades. Shock damping and AFD are semiactive damping methods [2,3]. Shock damping has a complex mechanism of vibration suppression and is not easy to implement [3], while AFD has a simple structure and is easy to manufacture.…”

An effective vibration reduction concept for automotive applications based on granular-filled cavities

“…Yokomichi et al (1996) have shown that a large vibration reduction can be achieved when an impact damper with granular materials is attached to the point where the modal amplitudes are relatively large, but the investigated systems possesses only three degrees of freedom, similar to that in Inoue et al (2011). Saeki (2002) adapted the impact dampers with granular materials for horizontally vibrating systems.…”