Achieve Vibration Reduction Research Articles

Design, Optimization, and Application of Nonlinear Energy Sink in Energy Harvesting Device

Vibration control has been of great interest to scientists and engineers for many years. Although linear vibration absorbers have been shown to be effective in mitigating vibrations at specific frequencies, their vibration reduction effect is usually limited to a narrow frequency bandwidth. Nonlinear energy sinks have attracted attention due to their better vibration reduction effect over a wider frequency bandwidth. In practical applications, the nonlinear energy sink devices can effectively absorb, dissipate, and convert energy from broadband excitation, so as to achieve vibration reduction and energy harvesting. However, research on energy harvesting based on the nonlinear energy sink is less mature than in linear systems. Multiple parameters of device design (e.g., damping size) affect the actual performance of the nonlinear energy sinks, but there is no exact method to simplify the design of the multiparameter nonlinear energy sinks. Since it is more difficult to implement electromagnetic and electrostatic energy harvesters, more research has focused on piezoelectric energy harvesters. This paper summarizes the research on the nonlinear energy sink and energy harvesting technology, including the introduction of the nonlinear energy sink, energy harvesting based on the nonlinear energy sink, and its application in various fields of energy harvesting. The paper also summarizes some important methods for solving the dynamical equations, as well as their advantages and disadvantages. The conclusions provide an outlook on the subsequent research of the nonlinear energy sink technology, such as the introduction of piezoelectric materials with high energy density, the benefits of balanced vibration suppression and harvesting of vibration energy, and the self-tuning of parameters in complex environments. It provides a powerful reference for the popularization and application of energy harvesting technology based on nonlinear energy sinks.

A nonlinear energy sink enhanced by active varying stiffness for spacecraft structure: theory, simulation, and experiment

A conventional nonlinear energy sink (NES) proposed for spacecraft structure can achieve vibration reduction without changing the resonant frequencies. However, large additional mass limits its engineering applications, and the robustness needs to be improved. A novel nonlinear energy sink with active varying stiffness (NES-AVS) device is proposed for reducing the mass of the conventional NES and enhancing the vibration reduction effects. A two degrees-of-freedom equivalent model of the scaled spacecraft structure is proposed. A harmonic balance method is applied to analyze the effect of the vibration reduction of the equivalent model, and the results are verified numerical simulations. The results show that the NES-AVS can achieve better vibration reduction effects, especially in small damping and mass. A finite element model of the scaled spacecraft structure with the NES-AVS is developed. The NES-AVS device is experimentally embedded in the scaled spacecraft structure. The variable stiffness device is realized by a steel plate with the compression force adjusted by a piezoelectric actuator. An active controller is used to control the actuator by the dSPACE module. The experimental results demonstrate that the NES-AVS has a better effect of the vibration reduction of the spacecraft structure than that of the conventional NES in multiple modes and different excitations. Compared with the conventional NES, the mass of the NES-AVS is reduced by 90%. The experiment and the theory have the same trends that the vibration reduction performance of the NES-AVS can be improved by adjusting the active control parameters. This work devotes to providing a new design scheme of the NES.

Design and analysis of a high-speed planetary rover with an adaptive suspension and spring damper

The development of deep space exploration has led to new exploration demands that cannot be met by traditional planetary rovers. This paper proposes a new wheeled rover that combines the advantages of passive all-wheel attachment and vibration reduction at high speeds. This rover can achieve vibration reduction in the vertical direction from ground excitation, preventing the instability of pitch and roll. Flexible wheels were used to reduce the high-frequency excitation of the ground on the rover. The design concept and mechanical principle of the proposed rover were comprehensively analyzed. A quasi-static kinematic model was developed to analyze the overstepping performance of the rover with this new design. Further, the response characteristics of the system to the ground excitation were investigated by vibration equations established using the Lagrangian method. The optimal parameters were obtained using a genetic algorithm to optimize the system with multiple objectives. Furthermore, the overstepping performance, all-wheel attachment, and vibration reduction of the planetary rover were verified through multi-body simulation. The proposed rover has considerable potential for missions such as the Mars sample return and planetary station construction.

Impact of phase configuration of a helical idler gear system on the vibration

The helical idler gear system has a lot of applications for reducer. The number of idler teeth and the orientation angle between the center lines of the three gears directly determine the mesh phasing. However, their impact is often ignored in system design. This paper presents the phase configuration relationship of the idler gear system, which can be used to control the mesh phasing by adjusting the number of idler teeth and orientation angle, to achieve vibration reduction. By establishing the dynamic model of an idler gear system considering phase configuration, the effects of the idler teeth number, orientation angle, and mesh phasing on the dynamic characteristics are investigated. For odd and even idler teeth numbers, the change law of mesh phasing with orientation angle is revealed. When the orientation angle is constant, the number of idler gear teeth will directly affect the system vibration response from the mesh phasing. The mesh phasing and its vibration response change periodically with the orientation angle. In each cycle, there is an optimal mesh phasing that reduces the variation response of different modes, and its value of different periods basically remains the same. In a period of mesh phasing, the suppression mechanism of mesh phasing under different vibration modes is studied. The variation law of the optimal mesh phasing with the rotational speed is revealed, and the vibration reduction effect can reach 20% on average. Finally, the correctness of vibration response and mesh phasing relationship is verified by experiments and a rigid-flexible coupling model. The above research provides a foundation for realizing vibration reduction by adjusting phase configuration.

The Application of Neural Networks to Modular Arrangements of Predetermined Time Standards

To study the method of reducing the low-frequency vibration noise of tires, a passenger car tire (205/55R16) is taken as the research object. The dynamic grounding characteristics and vibration reduction mechanism of the cat’s paw pad are analysed. The research showed that the swing deformation characteristics of paw pads during the walking process of cats are one of the main ways to reduce the impact from the ground and achieve vibration reduction and silencing. To analyse the influence of tire grounding on noise, tire grounding is divided into five areas, and the characteristics of ten tire grounding areas are analysed through tests. Pearson correlation analysis is used to obtain the characteristics of the eight most relevant grounding parameters with tire noise, and multiple linear regression is conducted between the characteristics of the eight grounding areas. The product of the correlation coefficient and the average value of the characteristics of the ground contact area shows that the central area of the tire tread contributes the most to the tire noise. The swing deformation characteristics of the bionic cat paw pad are realized by setting the staggered side branch pipe groove in the centre of the tire, and the vibration reduction characteristics of the bionic tire are analysed using the finite element method. The results showed that when the tire rolls, the amplitude and fluctuation range of the ground radial excitation force acting on the bionic tire are reduced compared with the original tire, and the vibration and noise characteristics of the tire are improved.

Influence of the Side Branch Structure Pattern of the Imitation Cat's Claw Function on the Vibration and Noise of Tires

To study the method of reducing the low-frequency vibration noise of the tire, a passenger car tire(205/55R16) is taken as the research object. The dynamic grounding characteristics and vibration reduction mechanism of the cat's paw pad are analyzed. The research showed that the swing deformation characteristics of paw pads during the walking process of cats is one of the main ways to reduce the impact from the ground and achieve vibration reduction and silencing. To analyze the influence of tire grounding on noise, the tire grounding is divided into five areas, and the characteristics of ten tire grounding areas are analyzed through tests. Pearson correlation analysis is used to obtain the characteristics of the eight most relevant grounding areas with tire noise, and multiple linear regression is conducted between the characteristics of the eight grounding areas. The product of the correlation coefficient and the average value of the characteristics of the ground contact area shows that the central area of the tire tread contributes the most to the tire noise. The swing deformation characteristics of the bionic cat paw pad are realized by setting the staggered side branch pipe groove in the center of the tire, and the vibration reduction characteristics of the bionic tire are analyzed by using the finite element method. The results showed that when the tire rolls, the amplitude and fluctuation range of the ground radial excitation force acting on the bionic tire are reduced compared with the original tire, and the vibration and noise characteristics of the tire are improved.

Dynamics Analysis of a Variable Stiffness Tuned Mass Damper Enhanced by an Inerter

A tuned mass damper with variable stiffness can achieve vibration reduction without changing the resonant frequency, but the large mass limits its engineering applications. To overcome this drawback, a novel tuned mass damper is proposed with the stiffness adjusted by a PI controller and the mass block replaced by an inerter. The tuned mass damper is attached to a two-degrees-of-freedom primary structure, and the dynamic equations are established. The frequency responses are obtained from a harmonic balance method and verified by numerical simulations. With the mass block of the tuned mass damper replaced by an inerter, the additional weight is reduced by 99%, and the vibration reduction performances are improved, especially in large excitation conditions. The vibration reduction rate increases with larger negative stiffness ratio and larger inertance ratio, while unstable responses appear with the parameters exceeding the thresholds. The optimum negative stiffness ratio and inertance ratio are searched by a frequency change indicator, and the maximum vibration reduction rate can reach 87.09%. The impulse response analysis shows that the proposed tuned mass damper improves the energy absorption rate. The primary structure and the vibration absorber engage in 1:1, 1:2, and 1:3 internal resonance with different impulse amplitudes. This paper aims to promote and broaden the engineering applications of the variable stiffness system and the inerter.

Control Method of Electrolytic Capacitor-Less Dual Inverter-Fed IPMSM under Periodic Load Torque Fluctuations

This paper proposes a control method for an electrolytic capacitor-less dual inverter for compressors. Single-phase motor drive systems are required to minimize vibrations, maintain a high power factor, and meet the limit for harmonic current emissions. The proposed control method achieves the harmonic reduction of the dq-axis currents, a high power factor, and a low grid current THD under periodic load torque fluctuations. The effectiveness of the proposed method is demonstrated via experimental results, using an open-end winding IPMSM and an electrolytic capacitor-less dual inverter. The proposed method reduced the 100Hz harmonic components of dq-axis currents up to 98% under periodic load torque fluctuations compared with an electrolytic capacitor-less single inverter. The results of FFT analysis of the input current show that the power factor and input current THD of the proposed method are equivalent to or superior to those of conventional methods. Therefore, the proposed control method can effectively achieve vibration reduction, a high power factor, and a reduction in the input current THD under periodic load torque fluctuations.

An improved nonlinear energy sink with electromagnetic damping and energy harvesting

A nonlinear energy sink can achieve vibration reduction without changing the resonant frequency of the system. In this work, an improved nonlinear energy sink is proposed by integrating with an electromagnetic system. The vibration reduction performance is further enhanced and an energy harvesting function is achieved at the same time. The dynamic equations of the primary system with the improved nonlinear energy sink are established, and the electromagnetic analysis is performed. The steady-state response of the system is solved with the harmonic balance method and verified by numerical simulations. The integration of the electromagnetic system provides additional damping to the nonlinear energy sink, and the vibration reduction performances under the harmonic and the impulsive excitations are enhanced. At the same time, the vibrational energy is effectively harvested by the electromagnetic system. The integration of the electromagnetic system does not change the resonant frequency of the system and retains the targeted energy transfer characteristic. The proposed system is applicable to the nonlinear energy sink with originally insufficient damping, and the electromagnetic coupling coefficient is a key parameter affecting both the vibration reduction and the energy harvesting performances. This integrated system is expected to provide a new strategy for multifunctional devices.

Adaptive predictive control based on ship magnetic levitation damping device

ABSTRACT In ship design, there are strict vibration-proof requirements for precision instruments. The vibration can cause structural fatigue of important equipment, which affects the service life. A magnetic levitation damping device is proposed to achieve vibration reduction. The uncertainties of the parameters in complex interference degrade the control performance of a magnetic levitation damping system. To deal with this problem, this paper proposes an adaptive predictive control based on the recursive least square adaptive law. First, a mathematical model based on the physical structure of the magnetic levitation damping device is established. Based on the mathematical model, a predictive controller is designed. It then combines the adaptive theory with the recursive least square adaptive law to address the problem of model uncertainties. Finally, it establishes the adaptive law to control the magnetic levitation damping device. Simulations show that this design has a fast response speed, strong robustness, and anti-interference ability.

Self‐tuning predictive control applicable to ship magnetic levitation damping device

In the ship design, there are strict vibration-proof requirements for precision instruments. Therefore, a ship repulsive magnetic levitation damping device is designed to achieve vibration reduction. And one self-tuning predictive control method is proposed to achieve the stable levitation of this device. Firstly, a predictive control (MPC) method with state constraints and input constraints is adopted to realise the stable suspension of the floater. The MPC can solve the problem of position imbalance of the magnetic levitation system under the external complex disturbances. Secondly, a self-tuning MPC method based on recursive least square is proposed to solve the problem caused by the fixed parameters of the traditional predictive controller. At the beginning of each control cycle, the recursive least-squares (RLS) method is used to estimate the parameters of the system. Thus, the optimal control model could be obtained for the current situation. Then, this model is applied to the predictive controller to solve the problem of parameter fixation in the traditional predictive control. Finally, the simulation results show that it can improve the accuracy, dynamic response and anti-interference performance obviously.

Effect of Injection Parameters on Vibration of High Pressure Common Rail Diesel Engine for Light Vehicle at Idle Speed

With the progress of science and technology and the improvement of people’s living standards, the comprehensive performance requirements of automobiles are also increasing. Reducing engine’s vibration and noise is one of the important research contents in the field of automobile research. An experimental study was performed to investigate the effect of injection parameters on engine’s vibration at idle speed by using a four-cylinder high pressure common rail diesel engine. On the premise of not changing the components, the influence of each parameter on the vibration is compared and analyzed by changing the parameters such as main injection timing, interval of pilot-main injection, pilot injection quantity and rail pressure. The test results show that the vibration of diesel engine can be reduced by delaying the main injection timing properly, and the optimal interval of pilot-main injection is related to the main injection moment and the quantity of fuel injection. The determination of the pilot injection quantity must be determined by the pilot-main injection moment and the cycle injection quantity together in order to achieve vibration reduction. The increase of rail pressure will increase the vibration of the whole machine. Thus, the proper injection strategy is conducive to improve engine vibration characteristics.

A novel negative stiffness magnetic spring design for vehicle seat suspension system

By employing a couple of columnar magnets with a specific arrangement, a negative stiffness magnetic spring (NSMS) is designed, modelled and then experimentally validated in this paper. Such a magnetic spring with negative stiffness can be used for a semi-active seat suspension to achieve vibration reduction on vehicle drivers. Extensive simulation analysis and experimental validation based on static and vibration responses reveal that NSMS brings the beneficial low dynamics stiffness for seat suspension and reduces the resonance frequency vibration during the vertical excitation without compromising loading capacity. Besides, a semi-active seat suspension system with the NSMS can achieve excellent performance of low-frequency vibration suppression (around 28.8 % acceleration reduction under random excitation).

Review of Phononic crystals and acoustic metamaterials

As a new type of acoustic functional material, phononic crystal has great research value and application environment. It is a periodic structure of two or more elastic materials, which are derived from photonic crystals. The main research work on phononic crystals focuses on the two band gap formation mechanisms of Bragg scattering and local resonance, and some new methods of vibration reduction and noise reduction can be obtained by studying its banding mechanism. Similarly, a “metamaterial” has been proposed for the ability to achieve new vibration reduction and noise reduction, which is a composite structure or material with physical properties not available in natural materials. By analysing the acoustic metamaterials of various structures, in this work we can understand how to achieve vibration reduction and noise reduction under the local resonance mechanism.

Rotational invariance in the design of structures with imbedded acoustic black hole vibration absorbers

The acoustic black hole (ABH) effect, where the wavespeed of a structure is intentionally reduced to near zero by altering its thickness according to a power-law taper, has been utilized on plates and beams to achieve vibration reduction. Several ABH designs have been proposed for uniform beams including the inverted and the double leaf ABH. However, these designs are only applicable for reducing flexural vibration in a single dimension. A rotationally invariant concept is presented where the imbedded ABH is symmetric around the center line of the beam. Various damping configurations are then applied to the rotationally invariant ABH and their respective amounts of vibration reduction are compared. Finally, the challenges of manufacturing such an ABH design will be discussed in the context of three-dimensional printing and additive manufacturing.

Suspension hybrid control for in-wheel motor driven electric vehicle with dynamic vibration absorbing structures

This paper presents a hybrid control strategy for suspension of the in-wheel motor (IWM) driven electric vehicle (EV) to improve vehicle ride comfort and reduce IWM vibration. A quarter vehicle model with the dynamic vibration absorbing structure (DVAS) is first developed. Different from the traditional suspension system, the DVAS uses an extra spring-damper system to achieve vibration reduction. The dynamics and boundary models for two commercially available and controllable dampers are then presented. Both dampers in the suspension and the DVAS are used to allocate the hybrid control force synthesized depend on the system responses. Simulation results for excitations of both random road and bump input are finally analyzed, and the proposed hybrid controller can simultaneously improve ride comfort and reduce IWM vibration compared to the traditional suspension system.

동관 벤딩을 위한 열처리로 설계 및 성능평가에 관한 연구

The air-conditioning industry is closely related to types of lifestyles, climate, and products. With the improvement of national income, the pursuit of pleasant living and working environments, and South Korea's four seasons and distinct climatic conditions, demand for air conditioning has increased. In addition, the industry is becoming increasingly precise and cooperative, and the increase in the domestic production of sophisticated air conditioning and continued growth of future industrial cooperation are expected to rapidly rise. Accordingly, the study of air piping systems can improve the productivity and quality of products and cost savings and can achieve vibration reduction. Additionally, using a heat treatment furnace for copper tube annealing treatment reduces the risk of using an oxy-acetylene torch.

Active twist control methodology for vibration reduction of a helicopter with dissimilarrotor system

In this work, an active vibration reduction of hingeless composite rotor blades withdissimilarity is investigated using the active twist concept and the optimal control theory.The induced shear strain on the actuation mechanism by the piezoelectric constantd15 from the PZN–8% PT-based single-crystal material is used to achieve more active twistingto suppress the extra vibrations. The optimal control algorithm is based on theminimization of an objective function comprised of quadratic functions of vibratory hubloads and voltage control harmonics. The blade-to-blade dissimilarity is modeled using thestiffness degradation of composite blades. The optimal controller is applied tovarious possible dissimilarities arising from different damage patterns of compositeblades. The governing equations of motion are derived using Hamilton’s principle.The effects of composite materials and smart actuators are incorporated into thecomprehensive aeroelastic analysis system. Numerical results showing the impact ofaddressing the blade dissimilarities on hub vibrations and voltage inputs requiredto suppress the vibrations are demonstrated. It is observed that all vibratoryshear forces are reduced considerably and the major harmonics of moments arereduced significantly. However, the controller needs further improvement to suppress1/rev moment loads. A mechanism to achieve vibration reduction for the dissimilar rotor systemhas also been identified.

Time-Varying Controller for Temperature-Dependent Viscoelasticity

There are internal-variable techniques that account for the frequency-dependent behavior of viscoelastic materials, but the temperature dependence of these materials has received much less attention. Two methods for designing controllers robust to temperature disturbances are given: (1) Modal reference adaptive control and (2) time-varying pole placement control. Examples that demonstrate the strengths and weaknesses of each are given. The results show that it is possible to achieve vibration reduction while simultaneously rejecting the effects of a temperature disturbance. This work shows that both the frequency and temperature dependence of viscoelastic materials can be modeled with internal variables.

Robust Individual Blade Control Algorithm for a Dissimilar Rotor

A new control methodology is formulated for vibration reduction at the rotor hub by controlling trailingedge e aps. The novelty of the proposed methodology lies in its ability to control each rotor blade separately and optimally, taking into account blade-to-blade dissimilarities, while using exclusively e xed-frame measurements. The controller is formulated in the time domain and adaptively generates in real time individual control inputs to the trailing-edge e aps to achieve vibration reduction. Numerical simulations using a hingeless rotor model show that thecontrollergeneratescontrolinputsto each blade,taking bladedissimilaritiesinto account, andsuccessfully minimizes hub vibrations. Nomenclature CT=ae = blade loading F = e xed-frame load F0 = uncontrolled e xed-frame load IK = identity matrix of size, K kN=rev = integer multiple of N times the rotor frequency N = number of rotor blades Ns = number of samples per revolution R = rotor radius S = permutation matrix ® = sectional angle of attack ± = e ap dee ection angle @®=@± = e ap effectiveness π = advance ratio A = rotor revolutions per minute Subscripts k = blade number n = iteration number