Variable stiffness tuned particle dampers for vibration control of cantilever boring bars

This research proposes a novel type of variable stiffness tuned particle damper(TPD)for reducing vibrations in boring bars.The TPD integrates the developments of particle damping and dynamical vibration absorber,whose frequency tuning principle is established through an equivalent theoretical model.Based on the multiphase flow theory of gas-solid,it is effective to obtain the equivalent damping and stiffness of the particle damping.The dynamic equations of the coupled system,consisting of a boring bar with the TPD,are built by Hamilton’s principle.The vibration suppression of the TPD is assessed by calculating the amplitude responses of the boring bar both with and without the TPD by the Newmark-beta algorithm.Moreover,an improvement is proposed to the existing gas-solid flow theory,and a comparative analysis of introducing the stiffness term on the damping effect is presented.The parameters of the TPD are optimized by the genetic algorithm,and the results indicate that the optimized TPD effectively reduces the peak response of the boring bar system.

Application of coupled multi-body dynamics-discrete element method for optimization of particle damper for cable vibration attenuation

With the application of the particle damping technology to cable vibration attenuation,the rootless cable damper overcomes the limit in installation height of existing dampers.Damping is achieved through energy dissipation by collisions and friction.In this paper,a coupled multi-body dynamics-discrete element method is proposed to simulate the damping of the damper-cable system under a harmonic excitation.The analyses are done by combining the discrete element method in EDEM and multi-body dynamics in ADAMS.The simulation results demonstrate the damping efficiency of rootless particle damper under different excitations and reveal the influence of the design parameters on its performance,including the filling ratio,particle size,coefficient of restitution,and coefficient of friction.

Experimental Investigation on the Vibration Attenuation of Tensegrity Prisms Integrated with Particle Dampers

Tensegrities made of tensile strings and compressed struts possess large strength-to-mass ratio values but tend to experience non-negligible vibration in dynamic environments because of poor structural damping.Here,we introduce particle dampers into a tensegrity prism to attenuate vibration,with the goal of establishing a lightweight and efficient approach of vibration suppression.To integrate the particle dampers and the tensegrity,a novel strut structure formed by assembling a solid strut and a hollow strut is devised,in which granular materials are inserted to develop a particle damper.The vibration attenuation performance of the tensegrity prism is investigated through exciter tests.According to the experimental parametric study,the influences of system parameters including excitation magnitude,the filling height of particles,particle size and the configuration of tensegrity prism on the vibration attenuation performance is analyzed.In addition,the experimental results regarding the dependence of the vibration attenuation on the system parameters are interpreted by the mechanism of collisions and frictions between particles and between particles and struts.The maximal vibration attenuation ratio of 76%can be achieved in the experiments.Thus,this research can provide insights into the design of lightweight tensegrity structures where vibration suppression is important,particularly in some dynamic environments.