Studies of the Performance of Multi-Unit Impact Dampers Under Stochastic Excitation

Abstract

The performance of particle dampers whose behavior under broadband excitations involves internal friction and momentum transfer is a highly complex nonlinear process that is not amenable to exact analytical solutions. While numerous analytical and experimental studies have been conducted over many years to develop strategies for modeling and controlling the behavior of this class of vibration dampers, no guidelines currently exist for determining optimum strategies for maximizing the performance of particle dampers, whether in a single unit or in arrays of dampers, under random excitation. This paper focuses on the development and evaluation of practical design strategies for maximizing the damping efficiency of multi-unit particle dampers under random excitation, both the stationary and nonstationary type. High-fidelity simulation studies are conducted with a variable number of multi-unit dampers ranging from 1 to 100, with the magnitude of the “dead-space” nonlinearity being a random variable with a prescribed probability distribution spanning a feasible range of parameters. Results of the computational studies are calibrated with carefully conducted experiments with single-unit/single-particle, single-unit/multi-particle, and multiple-unit/multi-particle dampers. It is shown that a wide latitude exists in the trade-off between high vibration attenuation over a narrow range of damper gap size versus slightly reduced attenuation over a much broader range. The optimum configuration can be achieved through the use of multiple particle dampers designed in accordance with the procedure presented in the paper. A semi-active algorithm is introduced to improve the rms level reduction, as well as the peak response reduction. The utility of the approach is demonstrated through numerical simulation studies involving broadband stationary random excitations, as well as highly nonstationary excitations resembling typical earthquake ground motions.

Analytical and experimental investigation on a multiple-mass-element pendulum impact damper for vibration mitigation

“…The fundamental theory on the mechanics of impact dampers devices has been examined by Masri and his research team. Starting from his pioneering work on the mechanical modeling of impact dampers [1][2][3], the research considered many problems and applications, which include "particle" dampers composed of either a single mass or multi-particle [4,5], studying both one-dimensional and three-dimensional motion of the particles [6,7]. More recently, Vakakis et al [8] analyzed the use of "impact dampers" for the suppression of aeroelastic instabilities on airplane wings (flutter during flight) and seismic vibration on buildings [9], by using a generalized concept of nonlinear energy sink (NES, [8]).…”

“…The paper describes the derivation of an analytical model for examining the dynamics of the system. The model is based on the extension of the concept of multi-particle impact damper [4]. The problem is formulated in the general context of vibrations on line-like structures.…”

Particle impact dampers: Past, present, and future

“…On the basis of the number of units and particles per unit, the traditional particle dampers can be grouped into four major types: the impact damper, [48] the multi-unit impact damper, [49,50] the particle damper, [51,52] and the multi-unit particle damper, [11,53] as shown in Figure 1. The development and evolution of these four fundamental types of particle dampers have broken the traditional single design concept, laying a solid foundation for the development of the subsequent multiform particle dampers.…”

Simultaneous Vibration Control Using an Impact Damper System in Horizontal and Vertical Directions

“…，さらには，複数のインパクトダンパユニットを設 置した場合の検討 (6) (7) がなされている．一方，主振動系として連続体を対象に，そこにインパクトダンパを適用 して高次振動モードの制振を試みた報告がある (8) ．また，衝突体の個数に関連した研究も多く，衝突体の個数が 数個の場合から無数に近い場合(粒状体衝撃ダンパと呼ばれている)の検討までなされている Table 4 Types of impact between wall and impactor …”