Non-obstructive Particle Damping Research Articles

New floating slab track isolator for vibration reduction using particle damping vibration absorption and bandgap vibration resistance

• A new floating slab track vibration isolator is developed using particle damping vibration absorption and bandgap vibration resistance. • Using the low-frequency vibration reduction effect of non-obstructive particle damping (NOPD), the attenuation of resonance peaks in the begin of bandgap frequency range is realized. • A coupled train-floating slab track-bridge dynamic model is established to investigate the vibration isolation capability. The environmental vibrations caused by rail transit continue to increase in importance. Even though there are a variety of efficient vibration reduction measures, there is still room for further improvement by trying new, effective vibration control mechanisms. In this paper, a new floating slab track vibration isolator is developed using particle damping vibration absorption and bandgap vibration resistance. Using the low-frequency vibration reduction effect of non-obstructive particle damping (NOPD), the particulate material is added to the outer ring vibrator to participate in vibrations, and the attenuation of resonance peaks in the begin of bandgap frequency range is realized. The energy loss factor and damping ratio of particle damping for different particle sizes are analyzed using a discrete element model. A finite element model with integrated particle damping effect is also formulated and the bandgap behavior of phononic crystal vibration isolator (PCVI) with additional particle damping is analyzed. The effect of particle damping is assessed by calculating the force transmission spectrum. In order to the investigate vibration isolation performance of the combined NOPD-PCVI when subjected to excitation from trains running at different speeds, a coupled train-floating slab track-bridge dynamic model is established. The results show that the NOPD-PCVI offers better vibration isolation than a steel-spring vibration isolator and the traditional PCVI (T-PCVI) in the frequency band of 50–150 Hz. The energy dissipation provided by particle damping and the bandgap damping of phononic crystals reduce the vertical accelerations of the bridge deck in the bandgap frequency band. Specifically, the total vertical accelerations of the bridge deck equipped with NOPD-PCVIs is reduced by 15.3 dB compared to steel springs, and 5.6 dB compared to T-PCVIs, respectively.

Vibration isolation performance of nonobstructive particle damping in a machine rack

Nonobstructive particle damping (NOPD) is a novel passive control technology with strong nonlinear-damping. Many scholars put effort into the research on the internal mechanism of NOPD. In contrast, the application of NOPD to engineering has not received much research effort. A theoretical model based on the principle of gas–solid flows, which is employed to evaluate damping effect of NOPD and to predict dynamic response of a machine rack by a co-simulation approach, is established in this paper. In view of the difference between damping effect acting on the lateral and bottom of NOPD holes directly, total damping force is divided into lateral damping force and bottom damping force according to the Janssen theory of stress changed direction. Moreover, NOPD technology is applied to a machine rack for discussing its vibration isolation performance. The results indicate that NOPD technology can suppress the intense vibration, especially between 4000 Hz and 8000 Hz. It is noted that the theoretical model of NOPD can accurately predict the dynamic response of the machine rack with NOPD. The 1/3 Octave vibration energy spectrum indicates that NOPD technics can dissipate the vibration energy of the machine rack at full frequency, especially in 31.5 Hz, and attenuation up to 39.75 dB.

Investigation of the energy dissipation of different rheology behaviors in a non-obstructive particle damper

Non-obstructive Particle Damping (NOPD) is widely used as an effective passive damping technique. However, the understanding of the energy dissipation mechanism and meso-scale behavior of the granular system in NOPD is not sufficiently in-depth. In this paper, the damping effectiveness of NOPD, as represented by the contour plot of the loss factor, was analyzed in combination with the motion modes of the granular system, and the energy dissipation mechanism was illustrated at the meso-scale. The results show that the different motion modes of rheology behaviors and meso-structure contribute to the variations in the damping effectiveness. Generally, the NOPD has the optimal damping effectiveness in the buoyancy convection state. The purpose of this paper is to provide a better understanding and theory support for the design and application of NOPD.

Non-obstructive particle damping using principles of gas-solid flows

Non-obstructive particle damping is a type of nonlinear damping related to the velocity amplitude of a vibrating structure. Many scholars have spent considerable time researching the damping and energy dissipation mechanism due to interparticle collision and friction, and they achieved corresponding results by using the principles of gas-solid flows and discrete element method. However, the damping mechanism due to kinetic dissipation between particles and gas has been entirely ignored. In this paper, a mathematical evaluation of the damping mechanisms due to kinetic dissipation is performed by using the principles of gas-solid flows. For systematic research into the application of non-obstructive particle damping technology in engineering practice, the improved model is perfectly embedded into finite element software by using co-simulation technology, in which MATLAB invokes a COMSOL file and controls the calculation process. A frequency analysis of the experiment verifies that the prediction accuracy of the improved model is obviously increased. Moreover, energy dissipation was explored by using the principles of gas-solid flows. Results indicate that particle damping technology can effectively control the structure vibration at a higher-order frequency. However, the energy dissipation mechanism takes effect at a lowerorder frequency.

Energy dissipation mechanism of a non-obstructive particle damper based on DEM simulation

The Non-obstructive Particle Damping (NOPD) has been widely used as an effective passive damping technique. However, the understanding of energy dissipation mechanism and meso-scale behaviors of granular system in NOPD is not in-depth enough. In this paper, the damping effectiveness of NOPD was analyzed combining with the motion modes of granular system and the energy dissipation mechanism was illustrated at the meso-scale. The results shows that the different motion states and meso-structure leading to the variations of the damping effectiveness. Generally, the NOPD has the optimal damping effectiveness in the buoyancy convection state. The purpose of this paper is to provide better understanding and theory support for the design and application of NOPD.

Dynamic response prediction of non-obstructive particle damping using principles of gas-solid flows

Particle damping is a kind of passive and strongly nonlinear damping for energy dissipation. Many researchers have expended huge amounts of effort and time to study internal mechanism of particle damping. However, there is not a systematic and feasible approach for estimating damping performance of non-obstructive particle damping (NOPD). In this paper, we performed studies to mathematically evaluate the damping effect of particle damping based on principles of gas-solid flows. In consideration of the structural characteristics of NOPD which granular materials should be filled into sealed cavity of vibrating structure and the damping act on lateral and bottom of holes in NOPD technology, the gross damping is divided into lateral damping and bottom damping by Janson's theory of stress change direction. And the damping coefficients are compiled into a plug-in by MATLAB and are invoked in FEM software by enterprise integration kits of COMSOL. Meanwhile the frequency domain and time domain analysis of the experiment are used to verify the prediction accuracy of dynamic vibration response of an aluminium cantilever beam which ONPD is imposed at the free end with different packing rate and granular material, the result indicate that the mathematical model has excellent performance to predict the dynamic vibration response of NOPD. Then, the relationship damping effect with the particle filling ratio, particle density and length-diameter ratio of the hole is also researched using co-simulation, it should be noted that larger packing rate and particle density, smaller length-diameter ratio of the hole can play excellent damping effects in NOPD.

The loss factor experimental characterisation of the non-obstructive particles damping approach

The Non-obstructive Particle Damping (NOPD) technology is an actuality research topic in vibration attenuation. In spite of the simplicity of this technology, the large number of NOPD parameters constitutes one of the problems in the computation of its damping contribution. In this paper, an experimental characterisation of non-obstructive particle damper under harmonic excitation was investigated. The experimental method which was developed allows the quantification of NOPD’s loss factor independently of the structure. Some system parameters such as excitation frequencies, excitation amplitudes and geometry of granular cavity were examined. Afterward, the characterised damping was converted to an equivalent viscous damping in order to predict the dynamic behaviour of a damped structure. The good correlation between experimental and numerical results illustrates the performance and the usefulness of the proposed method.

Experimental Study on Vibration Absorption Characteristic of Non-Obstructive Particle Damping Beam

Non-obstructive particle damping (NOPD) is developing in combination with particle damping technique, impact damping technique and material science. NOPD technology has good damping characteristic and nicer effect on vibration absorption. In the paper experiments of vibration absorption characteristic for beam applying NOPD are done and some conclusions are obtained, which affords important reference for engineering application of NOPD technique.

Research on the Vibration Attenuation of Heavy-Duty Machine Tool Based on Non-Obstructive Particle Damping (NOPD)

In this paper, the possibility of applying non-obstructive particle damping (NOPD) into the vibration attenuation for heavy-duty machine tool was analyzed and the experimental study on the characteristics of damping vibration attenuation was then carried out. First, the finite-element model for heavy planer type milling machine was built and then the stress state excited by the cutting force in the presence of the holes for filling particles located in the stand column was calculated. Secondly, based on the experiment, the acceleration time-domain waveform and the frequency response function (FRF) between NOPD application and the traditional solid cast-iron column of the planer type milling machine were obtained. Finally it is indicated that NOPD can effectively reduce the amplitude of vibration of heave-duty machine tool and has a good damping effect. Meanwhile, it has some additional effects, such as cost reduction, energy conservation and emission reduction.

Response Calculation for NOPD Beam by an Improved Algorithm Based on the Endochronic Theory and Test Verification

Non-Obstructive Particle Damping (NOPD) is a new damping technique which is based on traditional particle damping and impact damping technique. NOPD Structure has a good effect on decreasing sound and vibration. A new improved algorithm based on the endochronic theory is researched in the paper. Response calculation by the algorithm and tests for NOPD beam have been done in conditions of one, two and three holes filled with tungsten particles. Results show it feasible to calculate the response of NOPD structure by the improved algorithm, which affords an effective analysis method for engineering application of NOPD technique.

Experimental Investigation on Vibration-Reduced Characteristics of Non-Obstructive Particle Damping for Free Beam Structure

Non-obstructive particle damping is a composite damping technology based on traditional particle damping and impact damping. Being Compared with viscous elastic damping structure, advantage of NOPD is damping characteristic of system improved greatly on the basis of specific whole designing structure and whole mass. The technology has good general vibration-reduced outcome. Beam structure is a common structural element form in engineering application. Because of vibration or instability of beam under external excitation, in this paper, free beam is regarded as an object, and many factors affecting damping characteristic of NOPD are studied, which supplies referring results for engineering application of NOPD.

Theoretical Modeling and Experimental Verification for Structural Response of NOPD Based on Endochronic Theory

Non-obstructive particle damping (NOPD) is a new composite damping technology based on traditional partical damping and impacting damping, and it has good vibration-reduced results. Through studying thermodynamics constraint condition for non-inverse variation of inner tissue structure of the material, the endochronic theory obtained variation regularity of inner variable, further gave out evolution path of specific non-inverse thermodynamics variable under specific condition, and thus the constitutive relationship of the material was obtained. Based on endochronic theory, an incremental form of the endochronic constitutive relationship of discrete particle was derived, and then penalty element was introduced to solve the connection problem between structure and discrete particle, lastly finite element dynamics equation of NOPD composite structure was constructed. Based on the model of NOPD composite structure, simulation and experiment for response of NOPD free beam were made. It indicated that applying endochronic theory to analyze the response of NOPD is rational, which supplied an effective method for engineering application of NOPD.

A quantitative analysis on the energy dissipation mechanism of the non-obstructive particle damping technology

The non-obstructive particle damping (NOPD) technology has been recently developed from particle damping and impact damping technologies. In this paper, a quantitative analysis of the dissipation mechanism of NOPD based on a statistical theory is investigated for the first time to our knowledge. Under high-frequency vibrations, the dense granular motion of NOPD is very similar to turbulence. Thus, Kolmogorov's hypothesis in turbulence is adopted to describe the energy spectral density and velocity correlation function of the particles in the NOPD technology. It is shown that the NOPD's mean energy dissipation (per unit mass) increases with either the granular diameter or the volume ratio of the dense granular flow. The quantitative model for the NOPD technology presented in the paper should be useful in possible engineering applications of vibration reduction.

Structural Damping Enhancement Via Non-Obstructive Particle Damping Technique

Presented herein is a novel passive vibration damping technique that is referred to as “Non-Obstructive Particle Damping (NOPD).” The NOPD technique consists of making small diameter holes (or cavities) at appropriate locations inside vibrating structures and filling these holes to appropriate levels with particles which yield the maximum damping effectiveness for the desired mode (or modes). Powders, spherical shaped, metallic, non-metallic or liquid particles (or mixtures) with different densities, viscosities and adhesive or cohesive characteristics can be used.