Vibration Reduction Effect Research Articles

Torsional Vibration Reduction of Railway Vehicle Model by Controlling Internal Pressure of Air Springs using H-infinity Methods

As railway vehicles become faster and lighter, the vibration of carbody tends to increase and that makes the ride comfort worse. In lateral and vertical rigid-body vibration, a number of reduction technologies have been put into practical use, such as semi-active suspensions and variable vertical dampers installed between carbody and bogie. In elastic vibration, various methods have been studied, such as control by previously mentioned dampers, stack-type piezoelectric actuators. However, these methods focused on only the bending vibrations, it has been difficult to reduce multiple elastic vibration modes simultaneously. The authors propose a method to simultaneously reduce multiple elastic vibration modes, including torsional vibration, by controlling internal pressure of air springs. Since this method uses existing devices, it is superior in weight, cost, and maintenance compared to installing a new vibration compensator. First of all, we developed railway vehicle analytical model that can express elastic vibration including torsional vibration. Furthermore, we designed a control system by H-infinity methods and verified vibration-reduction effect on the stationary excitation test of simple railway vehicle model. As a result, it was confirmed that multiple elastic vibration modes, including torsional vibration, can be reduced simultaneously.

Research on Optimal Placement of Actuators of High-Rise Buildings Considering the Influence of Seismic Excitation on Structural Modes

Presently, most of the common placement methods of actuators are based on the structural response and system energy to select the optimal locations. In these methods, the contribution of controllability and the energy of seismic excitations to each mode of the structure are not considered, and a large number of cases need to be calculated. To solve this problem, the Clough–Penzien spectral model is combined with the Luenberger observable normal form of the system to calculate the energy of each state. The modal disturbance degree, considering modal energy and controllability, is defined by using the controllability gramian matrix and PBH system controllability index, and the modes are divided into the main disturbance modes (MDMs) and the secondary disturbance modes (SDMs). A novel optimal placement method of actuators based on modal controllability degree is proposed, which uses MDMs as the main control modes. The optimal placement of actuators and the vibration control simulation of a 20-story building model are carried out. The results show that the vibration reduction effect of the proposed placement method is significantly better than that of the method of uniformly distributed actuators (Uniform method) and the classical placement method of actuators based on the system controllability gramian matrix (Classical method).

A Hybrid Nonlinear Active Control Strategy Combining Dry Friction Control and Nonlinear Velocity Compensation Control

Friction dampers are widely used in structural vibration suppression in various fields, such as aeronautics, astronautics, robotics, precision manufacturing, etc. Traditional friction dampers are mainly used in a passive way to optimize vibration suppression with an immutable pressure around certain excitation. In this manuscript, a hybrid control strategy by considering both the friction force in the active control law and a nonlinear velocity compensation force is put forward: First, the normal force applied on the friction damper was adjusted to ensure its vibration reduction effect under different excitation for a first passive control; second, the active control law was established by combining the dry friction force and the velocity control force in the state space; lastly, the stability of the nonlinear control law was determined by Lyapunov criterion. Numerical simulations were conducted on a three degree-of-freedom system (3-DOF) based on the proposed hybrid control strategy, to show the control efficiency in vibration suppression and economic efficiency in energy input into the system. Simulation results showed that the proposed control law could reduce the amplitude of the active control force by about 5% without degrading the control efficiency.

Kalman filter identification method for micro-vibration transfer paths of satellites

Micro-vibrations on-board a satellite have degrading effects on the performance of certain payloads like observation cameras. The major sources of vibrations include momentum wheels, solar array drives, other rotary mechanical equipment, etc. These vibrations result in loss of the pointing precision and image quality of the payload through intricate transfer paths. To improve the accuracy of a satellite system with many vibration sources and complex transfer paths, it is necessary to determine the main transfer path of vibration. In this study, a path identification method is proposed and applied to the transfer system from the momentum wheel to the camera mount. First, the observer/Kalman filter identification (OKID) algorithm is used to acquire the state-space equation of each path subsystem. Then, the subsystem order is obtained based on the slope of the singular entropy increment. In the next phase, combined with the measured disturbance force of the momentum wheel, the displacement response of the target point is predicted. Finally, the dominant transfer path of vibration is achieved by calculating the vibration contribution of each path to the response point. The results indicate that the dominant transfer path is the axial path of the horizontal momentum wheel, which contributes to the vibration of the camera mount at most. Effective vibration reduction measures should be taken to this path to suppress the vibration signal. In comparing the identified displacement response with the finite element response of the camera mount under different noise conditions, the correlation coefficients are >0.85, which proves the accuracy and anti-noise capability of the identification method.

A piecewise negative stiffness mechanism and its application in dynamic vibration absorber

AbstractA new type of piecewise negative stiffness (NS) mechanism is designed and the relationship between the force and displacement is studied. At first, the prototype of the piecewise NS mechanism is established, and the stiffness characteristic of this mechanism is analyzed. Then, the piecewise NS mechanism is applied to dynamic vibration absorber (DVA) system to establish a dynamic model with the piecewise linearity. The differential motion equations are derived according to Newton's law of mechanics. The approximate analytical solution and the amplitude frequency curve of the system with the piecewise NS are obtained by means of the averaging method. The correctness of the analytical solution is proved by comparing with the numerical solution. In the end, the comparisons with two other traditional DVAs show that the system in this paper has better vibration reduction effect under the condition of harmonic excitation and random excitation.

Optimized Neural Network Prediction Model of Shape Memory Alloy and Its Application for Structural Vibration Control.

The traditional mathematical model of shape memory alloy (SMA) is complicated and difficult to program in numerical analysis. The artificial neural network is a nonlinear modeling method which does not depend on the mathematical model and avoids the inevitable error in the traditional modeling method. In this paper, an optimized neural network prediction model of shape memory alloy and its application for structural vibration control are discussed. The superelastic properties of austenitic SMA wires were tested by experiments. The material property test data were taken as the training samples of the BP neural network, and a prediction model optimized by the genetic algorithm was established. By using the improved genetic algorithm, the position and quantity of the SMA wires were optimized in a three-storey spatial structure, and the dynamic response analysis of the optimal arrangement was carried out. The results show that, compared with the unoptimized neural network prediction model of SMA, the optimized prediction model is in better agreement with the test curve and has higher stability, it can well reflect the effect of loading rate on the superelastic properties of SMA, and is a high precision rate-dependent dynamic prediction model. Moreover, the BP network constitutive model is simple to use and convenient for dynamic simulation analysis of an SMA passive control structure. The controlled structure with optimized SMA wires can inhibit the structural seismic responses more effectively. However, it is not the case that the more SMA wires, the better the shock absorption effect. When SMA wires exceed a certain number, the vibration reduction effect gradually decreases. Therefore, the seismic effect can be reduced economically and effectively only when the number and location of SMA wires are properly configured. When four SMA wires are arranged, the acceptable shock absorption effect is obtained, and the sum of the structural storey drift can be reduced by 44.51%.

Study on Performance Optimization and Physical Properties Testing of a New Type of High Thermal Conductive Damping Coating

Surface coating of damping paint is a common method to suppress structural vibration and reduce noise, but damping paint has poor thermal conductivity which limits it’ s application to transformers, reactors and other equipment that have high requirements for heat dissipation. In this paper, a new type of high thermal conductivity damping coating is prepared by emulsion polymerization, among which, a polyurethane emulsion with internal cross-linking structure and an acrylic emulsion with polymerization function are used as main agents, mica powder is used as the main damping function filler. By adjusting the proportion of non-metallic thermal conductive filler Al2O3 and thermal conductive fiber to explore the influence of different thermal conductive fillers on the thermal conductivity and damping performance of the damping coating. The paint is applied to aluminum and iron plates, and the sound insulation capacity is tested to study the influence of paint thickness, fiber addition, fiber type, viscoelasticity, and temperature aging on the sound insulation performance of damping sound insulation panels. The test results show that by adding thermally conductive filler Al2O3 and thermally conductive fibers, a thermally conductive network chain is formed inside the damping coating, which greatly improves the thermal conductivity of the coating while ensuring the damping performance and the effect of vibration and noise reduction.

Three-dimensional chiral meta-plate lattice structures for broad band vibration suppression and sound absorption

Phononic crystals (PCs) and acoustic metamaterials (AMs) have been studied due to their unique performance in generating elastic wave bandgaps. However, for vibration isolation structures with load bearing requirements, the conflict between stiffness and vibration control of the periodic structures is still a major concern. This paper presents a new type of three dimensional (3D) single-phase meta-plate lattice (MPL) structure consisting of chiral microstructures. The chirality is constructed by grooving the unit-cell surface of the plate-lattice structures with high bearing capacity. When the elastic wave propagates through the lattice structure, the energy is absorbed by the multiple vibration modes of the chiral surface, thus achieving the effect of broadband vibration reduction. In order to illustrate the isolation effect and the cause of bandgap formation, the propagation characteristics of elastic waves in a meta-plate beam are studied numerically and the isolation effect of the proposed lattice structures are validated by the vibration transmission tests. The sound absorption experiment is also carried out to evaluate the sound absorption performance of the new structure. This work offers an innovative method to develop new multi-functional lattice structures with both load bearing, vibration attenuation and sound reduction requirements. Vibration isolation effectiveness of MPL structure: (a) Experimental set-up and printed MPL structure. (b) Transmission spectrums obtained by simulation and experiment. (c) Transient responses at the input and output ends of the beam under 1991 Hz.

Parameters optimization and performance evaluation for the novel tuned inertial damper

This paper presents a double-flywheels architecture for a novel tuned inertial damper with grounded stiffness device acts as a passive vibration absorber. An undamped primary structure model with a single degree of freedom controlled by the proposed tuned inertial damper is developed and used to derive the equations of motion of the coupled system. The optimum frequency ratio and the optimum damping ratio are found based on the fixed points theory under harmonic force-excited primary structure. Then, the optimum grounded stiffness ratio is deduced. According to the change on the system parameters, there are three cases for the optimum grounded stiffness ratio, i.e., negative, zero and positive. It is found that from these three cases, the proposed tuned inertial damper with positive grounded stiffness device has the best control performance. When compared with some existing dynamic vibration absorbers, the proposed model in this paper in three cases presented the best control performance, featured by the broadest suppression bandwidth and the minimal vibration amplitude of vibration reduction effect under harmonic and random excitation.

Semi-Active Vibration Control Based on a Smart Exciter with an Optimized Electrical Shunt Circuit

A smart exciter coupled to cabin panels can be used as a new type of loudspeaker for emergency announcements in the aircraft cabin. The same device can also be used as a semi-active vibration control system which is effective in reducing the amplitude of structural vibration. The objective of this paper is to investigate the potential of vibration reduction using a smart exciter in combination with an optimized resistive-inductive shunt circuit, which serves as an absorbing network. First, the vibration reduction effect has been analyzed numerically using a simulation framework realized with COMSOL and MATLAB/Simulink. In a second step, the reduction effect of the smart exciter together with a resistive-inductive shunt circuit, which is produced by the Center of Applied Aeronautical Research (Zentrum für Angewandte Luftfahrtforschung GmbH, Hamburg, Germany), has been investigated experimentally. The results presented here prove that the smart exciter together with a resistive-inductive shunt can be highly effective in reducing structural vibrations.

Optimal Vibration Suppression Modification Method for High-Speed Helical Gear Transmission of Battery Electric Vehicles under Full Working Conditions

To improve the working performance of battery electric vehicle (BEV) high-speed helical gear transmission under full working conditions, combined with Tooth Contact Analysis (TCA) and Loaded Tooth Contact Analysis (LTCA), the vibration model of single-stage helical gear bending-torsion-axis-swing coupling system considering time-varying mesh stiffness was established. The genetic algorithm was used to optimize the tooth surface with the objective of minimizing the mean value of the vibration acceleration at full working conditions. Finally, a high-speed helical gear transmission system in a BEV gearbox was taken as a simulation example and the best-modified tooth surface at full working conditions was obtained. Experiment and simulation results show that the proposed calculation method of time-varying meshing stiffness is accurate, and tooth surface modification can effectively suppress the vibration of high-speed helical gear transmission in BEV; compared to the optimally modified tooth surface under a single load, the optimal modified tooth surface under full working conditions has a better vibration reduction effect over the entire working range.

Planar Swirl-shaped Acoustic Black Hole Absorbers for Multi-directional Vibration Suppression

A planar swirl-shaped Acoustic Black Hole (ABH) absorber is proposed and investigated in this paper. In addition to the well-known bending wave retarding phenomena, the speed of torsional waves in the curved ABH with a rectangular cross section is also shown to decrease with the thickness thinning. Alongside the enhanced bending-twisting coupling brought about by the planar and curvilinear configuration, the curved ABH absorber exhibits reduced orientation-dependent properties to cope with multi-directional rotational moment excitations, and meanwhile generates enriched dynamics and enhanced energy trapping and dissipation. As a result, the absorber enables broadband multi-directional vibration suppression when added on a primary thin structure. Experimental studies demonstrate that deploying multiple distributed ABH absorbers can entail effective, robust and broadband vibration reduction for an arbitrarily selected polygon plate. Analyses also confirm the dual vibration reduction mechanisms in terms of structural interaction and damping enhancement, both being fully played out through the proposed curvilinear ABH design.

UM-SIMULINK Co-simulation for the vibration reduction optimization of a magnetorheological damping steel-spring floating slab track

To further mitigate the low-frequency vibration of a vibration source induced by the natural frequency vibration of a floating slab track (FST), the key parameters including the maximum damping force and the displacement threshold of magnetorheological dampers (MRDs) were studied under different subway operating conditions. A Graphical user interface (GUI) co-simulation was proposed to investigate the dynamic responses of a magnetorheological damping Steel-spring FST (SSFST). The mitigation effect of different MRD parameters on vibration sources was evaluated with the environmental vibration prediction model. MRDs could reduce the Z-weighted vibration level of the FST and the tunnel wall simultaneously, but the control strategy was necessary to prevent excessively amplifying the mid-high frequency vibration of the tunnel wall. The deterioration of the track irregularity and the train characteristic frequency close to the natural frequency of the FST required an appropriate increase in the MRD maximum damping force. The displacement threshold should be determined in combination with the dynamic displacement generated by the axle load and the corresponding vibration reduction effect. When the same desired effect is obtained, the parameter matching with a smaller MRD damping force and a larger displacement threshold is recommended.

Design of a particle damper and experimental study on vibration damping of the pipeline

In this work, we designed a particle damper which can be conveniently clamped on to a pipeline without affecting the existing structure, showing a promising application in vibration reduction of real aircraft. Based on the designed particle damper, the impact of particle filling rate on the vibration reduction effect, the effect of EDEM simulation on the energy consumption of particles in the vibration process of the damper, and the result of actual vibration reduction test of particle damper installed on hydraulic pipeline were investigated. It is found that the vibration of the pipeline decreases first and then increases with the increase of particle filling rate. The particle filling rate corresponding to the maximum particle energy consumption rate is consistent with that of the minimum pipeline vibration acceleration during the test, that is, from 94.9% to 97.9%. The simulation results are in good agreement with the test results. Moreover, the vibration of the hydraulic pipeline and actual aircraft pipeline are both obviously suppressed after the installation of the particle damper. These results fully demonstrate the effectiveness and practicability of the aircraft pipeline particle damper.

Dynamic Analysis of Vibration Reduction and Energy Harvesting Using a Composite Cantilever Beam with Galfenol and a Nonlinear Energy Sink

This paper explores a new method for vibration control and energy harvesting by coupling a nonlinear energy sink (NES) with a cantilever beam containing giant magnetostrictive material. A mathematical model of the principal linear system under the action of an external harmonic force is established, and the dynamic equation of the system is derived using Newton’s second law, Hamilton’s principle, and nonlinear boundary conditions. The displacement responses of the system as functions of time and of frequency are obtained by using the Runge–Kutta method and harmonic balance method. The analytic results are found to be consistent with the numerical solution, confirming the accuracy and reliability of the calculated results. The frequency response and time response of the system with and without NES coupling, and with other parameters unchanged, were compared. The results show that the proposed structure can achieve excellent vibration suppression. The energy harvesting effect of the system as a function of time is also analyzed by the Runge–Kutta method, comparing results for different values of parameters such as NES mass, nonlinear spring stiffness, and damping coefficient. The results indicate that the proposed structure can achieve the desired effects of vibration reduction and energy harvesting, and that results can be optimized by adjusting the relevant parameters.

Determination method of tunnel blasting parameters using electronic detonator under changing condition of free surface

The technical potential of electronic detonator has not yet been fully utilized in tunnel engineering. An important reason is that there is no calculation method of blasting parameters supported by rigorous theory. The pivotal blasting parameters such as charge and delay time, etc. are mostly designed following ordinary mining method. And it can not solve the problem of calculation accuracy of blasting parameters after the formation of the second free surface. Taking Guanyinqiao Tunnel in Chongqing as the research background, based on the Anderson principle and the delay characteristics of the electronic detonator, a new method for designing the blasting parameters of electronic detonator is proposed under the different free surface conditions changing in the process of tunnel blasting, from single free surface to dual free surface. Firstly, based on the single-hole and single free surface blasting vibration curves of different charges acquired on site, the superimposed vibration of multiple blast-holes under each delay time was calculated one by one. After comparing the superimposed vibration curves of different charges and delays, it was determined the blasting parameters of single free surface, including the maximum single-hole charge and the optimal inter-hole delay. Secondly, according to the characteristics of the electronic detonator, the short-delay cut blasting field test was designed. By comparing the calculated waveform without considering the influence of the second free surface with the measured waveform affected by the vibration reduction effect of the second free surface, it was found that the second free surface had formed at 48 ms after initiation. Based on this, a single-hole blasting test was designed after the formation of the second free surface. By calculating the superimposed vibration velocity based on the single-hole waveforms before and after the formation of the second free surface, it was determined the blasting parameters under the dual free surfaces condition, including single-hole charge, inter-hole delay time, and delay between different types of holes. Finally, the calculation method of blasting parameters in the whole blasting process was formed. After the comprehensive analysis of the calculated results, the single-hole charge of the main cutting holes is 1.2 kg, and it is 1.4 kg of the auxiliary cutting holes, then the delay time between holes is 5 ms on site; the minimum delay time between the main cut holes and the auxiliary cut holes is 35 ms. The field test was carried out with the optimized parameters mentioned above, and it got high-efficiency footage as well as a low vibration velocity.

A theoretical vibration‐reduction effect analysis of the floating slab track supported by nonlinear variable stiffness isolators and semi‐active magneto‐rheological dampers

Nonlinear vibration control theory has resolved some bottleneck problems that cannot be solved by traditional linear vibration control theories. In this study, intelligent controllable magneto-rheological dampers (MR-Ds) and high-static-low-dynamic variable stiffness vibration isolators (VS-VIs) are innovatively applied to a traditional steel-spring floating slab track (FST) to improve its low-frequency vibration-reduction effect. To determine the reasonable parameter group of the VS-VI and the parameter matching when used with MR-D, parameter groups were first preliminarily proposed through static and dynamic analyses of the equivalent single-degree-of-freedom (SDOF) model of the FST. A vertical vehicle–variable stiffness-magneto-rheological FST coupled dynamic model was established, and the parameter group was optimized based on safety and vibration-reduction analyses. The simulated results showed that the positive and negative stiffnesses were the key parameters that determined the stiffness nonlinearity level and dynamic support capacity of the VS-VI. Improving the positive stiffness is necessary to achieve a low-dynamic stiffness under no vehicle load and to ensure the millimeter-level dynamic displacement of the FST under vehicle load. An appropriate stiffness nonlinearity level can achieve a better vibration-reduction effect, and excessive nonlinearity level will not bring more significant improvements. The damping ratio in the dynamic analysis is a key parameter to prevent the jumping phenomenon, and the recommended value should not be less than 5%. Moreover, when the VS-VI and the MR-D were efficiently incorporated, a smaller MR damping force and larger displacement threshold could not only achieve a better vibration-reduction effect but also reduce the energy consumption.

Noise annoyance and vibration perception assessment on passengers during train operation in Guangzhou Metro.

With the development of urban rail transit, taking the metro train has become one of the main modes of transportation, and passengers have an increasing demand for the comfort of taking the metro trains. This paper mainly discusses the impact of noise and vibration caused by metro train on passengers. All 13 metro lines in Guangzhou, China, were selected to conduct the questionnaire survey on the subjective perception of 601 respondents. At the same time, noise and vibration measurements were carried out in the train. The results show that the distribution of noise and vibrations along the metro lines is not uniform, and 50.6% of the interviewees are disturbed by noise. Wheel-rail squeal was found to be the most annoying and disturbing noise source. Three dose-response relationships for noise, vertical vibration, and horizontal vibration are proposed, respectively. The proposed dose-response relationship can be applied to the evaluation of noise annoyance or vibration perception in an environment similar to metro lines. Once the noise or vibration level of a metro line is obtained, the noise disturbance or vibration perception can be estimated. As for the dose-response relationship of vibration perception, people's sensitivity to vibration is much lower than that to noise. Horizontal vibrations are more acceptable to passengers, while vertical vibrations are more disturbing to passengers. The results are helpful to predict the noise annoyance and vibration perception of train passengers between metro stations, and to achieve the purpose of designing effective noise and vibration reduction measures.

Parameters optimization of dynamic vibration absorber based on grounded stiffness, inerter, and amplifying mechanism

In the field of dynamics and control, some typical vibration devices, including grounded stiffness, inerter and amplifying mechanism, have good vibration isolation and reduction effects, especially in dynamic vibration absorber (DVA). However, most of the current research studies only focus on the performance of a single device on the system, and those DVAs are gradually becoming difficult to meet the growth of performance demand for vibration control. On the basis of Voigt dynamic vibration absorber, a novel dynamic vibration absorber model based on the combined structure of grounded stiffness, inerter, and amplifying mechanism is presented, and the analytical solution of the optimal design formula is derived. First, the motion differential equation of the system is established, and the normalized amplitude amplification factor of the displacement is calculated. It is found that the system has three fixed points unrelated to the damping ratio. The optimal frequency ratio is obtained based on the fixed-point theory. In order to ensure the stability of the system, it is found that inappropriate inerter coefficient will cause the system instable when screening optimal grounded stiffness ratio. Accordingly, the best working range of inerter is determined. Finally, optimal grounded stiffness ratio and approximate optimal damping ratio are also obtained. The influence of inerter coefficient and magnification ratio on the response of the primary system is analyzed. The correctness of the derived analytical solution is verified by numerical simulation. Compared with other dynamic vibration absorbers, it is verified that presented model has superior vibration absorption performance and provides a theoretical basis for the design of a new type of dynamic vibration absorbers.

Design and Random Vibration Simulation of the S-shaped Vibration Damping Structure for Transport Pallet

In order to improve the safety of containerized transport unit in palletized transport, this paper designs a new structural vibration damping pallet. Compared with the pallets that rely on material damping, the former is less affected by the environment, and can limit the horizontal and vertical deformation, making it elastic vertically to ensure the stability of cargo stacking. The relationship between its elastic deformation and material properties, size parameters and loads is obtained by establishing the mechanical model of the S-beam damping structure. Through finite element simulation of the static elastic deformation of the pallet, the relative error between the simulation and the theoretical results is only about 1%, which verifies the theoretical basis of the vibration damping structure and reliability of the finite element modeling. In random vibration simulation, the S-shaped structural vibration damping pallet has a damping effect from 11.2Hz, and it reduces vibration energy of the traditional pallet by 46.3% and 9.3% less than the EPE material damping pallet and covers a wider damping frequencies. The results show that the pallet has obvious vibration reduction effect, can effectively protect the cargo and increase security of palletized transport.