Application Of Dynamic Vibration Absorbers Research Articles

Application of dynamic vibration absorber for vertical vibration control of corrugated rolling mill

Application of dynamic vibration absorber for vertical vibration control of corrugated rolling mill

Vibration Mitigation of Wind Turbine Towers Using Negative Stiffness Absorbers

The application of dynamic vibration absorbers (DVA) to Wind Turbine (WT) towers has the potential to significantly improve the damping of the tower and the nacelle dynamic responses, increasing thus the reliability of WTs. The Tuned Mass Damper (TMD) is limited by the requirement of large masses, in association to its installation location. In this study, two alternative concepts are considered. First, the nacelle is released from the WT tower, using a low stiffness connection. This option is based on the seismic isolation concept. Additionally, a novel passive vibration absorption configuration is implemented, based on the KDamper concept. The KDamper is essentially an extension of the TMD, introducing negative stiffness (NS) elements. Instead of increasing the additional mass, the vibration absorption capability of the KDamper can be increased by increasing the value of the NS element. Therefore, the KDamper always indicates better isolation properties than a TMD with the same additional mass. For the nonlinear dynamic response of the WT a build-in house software is developed. The dynamic performance of the proposed vibration mitigation concepts is numerically examined. All methods present superior dynamic behaviour as compared to the uncontrolled structure, however only the KDamper-based designs significantly increase the effective damping of the WT tower, retaining the additional masses in reasonable ranges.

Application of dynamic vibration absorbers in designing a vibration isolation track at low-frequency domain

This paper aims to develop a low-frequency vibration isolation track based on passive vibration isolation theory and vehicle–track interaction analysis. First, a preliminary low-frequency vibration isolation track is proposed by attaching multiple dynamic vibration absorbers to a discontinuous floating slab track, and the optimal design parameters of the multidynamic vibration absorber are determined by searching the minimum values of two assessment functions. Further, a three-dimensional coupled dynamic model of a metro vehicle and the low-frequency vibration isolation track is established by using Ansys Parametric Design Language, where the equations of motion of the vehicle subsystem and the wheel–rail contact calculations are incorporated in the software Ansys using the Ansys Parametric Design Language, and the low-frequency vibration isolation track subsystem is directly created by using common elements in Ansys. The vibration isolation performance of the preliminary low-frequency vibration isolation track with multidynamic vibration absorber is investigated under harmonic load and vehicle dynamic load, respectively. Results show that the slab acceleration and supporting force are significantly reduced at low frequencies of 10–20 Hz compared with those of the traditional floating slab tracks. Finally, an improved low-frequency vibration isolation track is developed for actual manufacturing and practical application, and simulations show that the improved low-frequency vibration isolation track exhibits a more robust vibration isolation performance even if optimal design parameters have variations due to manufacturing errors or material deterioration.

Practical aspects of design, tuning, and application of dynamic vibration absorbers

Theory of dynamic vibration absorbers is a classic topic that has been thoroughly researched. Nevertheless, implementing the dynamic system in a structure and applying it properly still meet some challenges that have not been adequately addressed in the technical literature. Some of practical problems include achieving thermal stability, building a damped device with the desired undamped frequency, providing mechanisms for tuning or adjusting the dynamic absorber in situ, and effective tuning of multiple absorbers. The paper describes a new patented design of dynamic vibration absorber for optical tables together with the new method of tuning. The tuning procedure uses only one sensor and does not require access to the moving mass. Applications include suppressing flexural resonance vibrations of standard optical tables and the recent project on vibration control of large support bench for unique petawatt laser system at Lawrence Berkeley National Laboratory.

Application of Dynamic Vibration Absorber in Noise Control of Whole Vehicle

As cars become quieter the sound quality of components becomes more critical in the customer perception of car quality. Considering that middle frequency noise plays an important roll for internal noise, the noise signals in the range from200Hz to 500Hz are specially emphasized. Then the acoustic evaluation parameters, such as Sound Pressure Level, Acceleration have been evaluated. Judged from experiences and measuring results, an abnormal noise comes from engine mounts, through the use of dynamic vibration absorber on engine mounts, Vibration on engine mounts and Sound Pressure Level in interior vehicle were greatly improved. At the same time, subjective evaluation also indicated that there was no complaint any more in passenger compartment. Dynamic vibration absorber can properly solve the abnormal noise.

Application of dynamic vibration absorbers in floating raft system

To improve the isolation performance of the traditional floating raft system, dynamic vibration absorber (DVA) is introduced into floating raft in this research. The mathematical models of floating raft system consisting of beams are implemented by assembling the mobility matrices of the subsystems. Then the power flow transmission characteristics of the coupled system with/without the DVAs are investigated to evaluate the vibration reduction performance of DVAs. Numerical simulations are performed to explore the influence of several parameters, such as the setting positions, damping and mass of the passive DVAs, on the vibration reduction effects of DVAs. Moreover the vibration reduction performance of the semi-active absorber adjusting its stiffness adaptively is analyzed for the case of time-varying frequency excitation. In addition, the vibration reduction effects of semi-active DVAs under multi-frequency excitation are investigated. The results show that DVAs can significantly improve the isolation performance of floating raft system.

Application of dynamic vibration absorbers in structural vibration control under multi-frequency harmonic excitations

In this research, the response properties of a single-degree-of-freedom system under dual harmonic excitation are analyzed to provide some principles for the choice of time span and step in the simulations. The performances of dynamic vibration absorber (DVA) and state-switched absorber (SSA) are compared. The results indicate that dual DVAs almost have the same performance as the SSA. Moreover, dual DVAs compared with the SSA have some advantages such as lower ratio of tuning frequencies, more rapid optimization process and lower requirement for the anti-fatigue property of the material. Furthermore, the performances of different frequency-tuning methods are investigated. It is shown that the one–one method almost has the same performance as the optimization method and it does not need time-consuming optimization process.

Application of a Dynamic Vibration Absorber to a Piecewise Linear Beam System

This paper deals with the application of a linear dynamic vibration absorber (DVA) to a piecewise linear beam system to suppress its first harmonic resonance. Both the undamped and the damped DVAs are considered. Results of experiments and simulations are presented and show good resemblance. It appears that the undamped DVA is able to suppress the harmonic resonance, while simultaneously many subharmonics appear. The damped DVA suppresses the first harmonic resonance as well as its super- and subharmonics.

A Study on Jitter of Serial Printer (Vibration Control of Carriage System by Dynamic Vibration Absorbers)

A serial printer sometimes generates a vertical striped pattern in the printing image. This is known as jitter and caused by vibration of the print-head carriage system in moving direction. The vibration of carriage due to meshing of synchronous belt is the main reason causing jitter. In this paper, the application of dynamic vibration absorber is proposed to reduce the vibration of the carriage system. The frequency response of the carriage system attached with absorbers is derived. An equivalent vibration system of linear motion is used in the analysis instead of original carriage system. Designs of absorbers are discussed for the purpose of reducing the vibration due to belt meshing. Both calculations and experiments are carried out and their results show that the dynamic vibration absorber is effective.

Vibration attenuation of tennis racquets using tuned vibration absorbers

Modern tennis racquets are made of advanced composite materials resulting in significantly lighter and stiffer structures than traditional wooden or metal racquets. While these high-tech structures have had a profound effect on improving the performance of tennis players, modified structural dynamic behaviour and in particular the vibrational response felt by the players has caused some concern thus raising particular interest in vibration attenuation and the application of dynamic vibration absorbers in modern tennis racquet technology. The use of dynamic vibration absorbers is common in engineering applications where there is a need to attenuate high vibration levels caused by resonant response. The effect of using tuned vibration absorbers to attenuate certain key modes of vibration of a tennis racquet is examined in this paper. Attachment of tuned absorbers has traditionally been affected by attaching to antinodal locations of the primary structure. This does not necessarily convey the effectiveness of attachment at other available locations. To overcome this, an effectiveness criterion is formulated and used to indicate the most beneficial attachment location for the devices. The impulse responses obtained from the model are indicative, if not absolute, that tuned vibration absorbers with small mass values could prove effective in the attenuation of key structural modes of the racquet.