Vibration Reduction Research Articles

Lateral vibration reduction in vertically installed shafts by active control with LMS algorithm

Machines such as generators and electric motors that use vertical shafts must avoid noise and heat problems caused by vibration. Especially in the case of vertical hydro generators, vibrations caused by water flow through the turbine and imbalance of components can lead to poor performance, premature wear of components, and even system failure. Therefore, effective control of shaft vibration is very important for system maintenance and stable operation. To solve this problem, an active control method with Least Mean Squares(LMS) algorithm were applied to the lateral vibration. In the study, the vertical shaft and the active bearing were modeled using the Finite Element Method (FEM), and the external hydraulic force was employed with an unbalanced mass. Simulations were conducted and effectiveness of the simulation results was verified through the active control experiments. These results show that active bearings have the potential to solve vibration problems and extend the life of machines with vertical shafts, such as generators or electric motors.

A robust force identification method based on L1+2-norm approximation theory

Obtaining the real force of the structure is the basic condition for efficient vibration reduction design. However, the uneasiness and instability of the inverse problem make the force identification still challenging. On the basis of L2-norm regularization, we propose a new method for force identification based on L1+2-norm approximation theory. By introducing the L1-norm penalty operator, a joint norm approximation optimization model is constructed to limit the non-zero force and punish the force value which approaching to zero, so that it can adapt to the identification of various types of forces. Then the optimal force solution is obtained by using the Primal-dual interior point method. Finally, the effectiveness and accuracy of the proposed method are verified by numerical simulation and experiment of asymmetric plate and double-layer plate structures. Different from previous studies, the L1+2-norm method in this work has high robustness, considers the characteristics of sparse regularization and L2-norm regularization, and can adapt to the identification of continuous forces and sparse forces at the same time, which has potential engineering application value.

Vibration reduction of an electric vehicle heat exchanger by controlling the polarization of its ferroelectric ceramics

The growing requirements in terms of CO2 emissions reduction in transports renders necessary the development of new electric traction technologies. This results in new technical constraints for equipment manufacturers, forcing them to reduce the acoustic emissivity of their new products inside and outside vehicles. Heat exchangers for electric cars are part of this new product category. High voltage supplied by the battery of electrical vehicles requires introduction of a new energy conversion process and technology. To this end, components based on ceramics containing barium titanate (BaTiO3) with high electrocaloric coupling properties are selected to provide the heating function. Baryum titanate is ferroelectric. This category of materials is subjected to piezoelectric and electrostrictive effects. The vibrations induced in the components (rods) containing the BaTiO3 ceramics are transmitted through the system, and cause undesired acoustic radiation. This coupling is a suffered effect and is not taken into account in the integration process during the rods manufacturing. In this study, an experimental characterization is proposed to identify the involved electromechanical coupling coefficients. Numerical simulations of the vibrations induced by BaTiO3 are carried out and used to study the possibility of attenuating them by controlling the polarisation of the ceramics or by geometric modifications.

Comparison of active and passive vibration control techniques for electric drive power electronic subsystem: Experimental validation

Reducing vibration and noise from power electronics components is vital for enhancing the performance and acceptance of electric vehicles, emphasizing the need for effective mitigation strategies in sustainable transportation. This paper compares passive and active vibration techniques, with a specific focus on utilizing particle damping for passive vibration control. The method achieves vibration reduction through viscoelastic deformation and friction resulting from the movement and collisions of granular material within the cavity. This contribution outlines diverse design strategies for integrating particle dampers into power electronic components. The active control approach, operating typically in the 50 Hz to 1200 Hz frequency range, can concurrently support passive noise treatments. Piezoelectric ceramics serve as both actuators and sensors in active noise reduction. Following the identification of dominant mode shapes, appropriate actuator and sensor positions are chosen. The control problem of the smart system is then addressed, opting for a velocity feedback control algorithm in a real collocated design. This algorithm computes input signals for actuators bonded to the outer surface, achieving significant active damping effects. Lab-tested techniques are validated in real-world conditions with a full-scale electric-drive toolkit, affirming their efficacy in reducing vibration and noise and underscoring their potential for implementation in electric vehicles.

Study on subway resilient wheel's influence on noise inside the vehicle and in the bogie area through the in-situ measurements

Based on a new type of resilient wheel installed on a subway train, a measurement campaign is devised to evaluate the effectiveness of the resilient wheel in reducing noise. For reference, the same series of tests are carried out on another train of the same type but fitted with conventional wheels. The measurements involve the noise of various parts of the vehicle-track system which are used to investigate the sources of wheel-rail rolling noise, the noise inside the vehicle, and the noise close to the wheels. The series of tests are conducted on the normal-conditioned and corrugated track on which the two sets of trains pass through at difference speeds. It is found that the decrease of interior noise measured on the corrugated track is within the range of 0.2~10.5 dB(A), which is greater than on normal conditioned track after using the resilient wheels. This attributes to the frequency range available for vibration reduction by using the resilient wheel covers the dominant frequency range of the excitation from corrugation.

Annoyance assessment of the combined effect of railway noise and vibration including physiological measurements

The prediction of annoyance due to railway transportation in residential areas is crucial to correctly dimension noise and vibration reduction solutions. In situ annoyance assessment for multiple exposition scenarios requires to convince many residents to take annoyance tests combined with noise and vibration measurements inside their homes. Such approach is not adapted to large-scale experiments. Therefore, the VibAcouPhysio project aims at studying annoyance due to railway noise and vibration in laboratory conditions. A vibrating platform combined with a high-quality sound reproduction system has been designed for this project to reproduce the noise and vibrations of a train pass-by. Annoyance is estimated by multiple means including questionnaires, cognitive tasks performance assessment and various physiological measurements. Twenty participants were exposed to various train pass-by signals as if they were seating at a table inside their housing. The results show a significant correlation between physiological metrics, the annoyance evaluated in the questionnaires and the physical indicators derived from the noise and vibration signals. The main purpose of the VibAcouPhysio project is to rank various physical indicators describing noise and vibration signals according to their correlation to the perceived or measured annoyance.

Virtual acoustic black holes as a means to achieve low-frequency vibration reduction

Acoustic black holes (ABH) offer exceptional broadband vibration capabilities but have the inherent drawback of being only effective beyond a specific cut-off frequency. The most straightforward approach to set this threshold to a low value is to increase the ABH length. However, such a strategy leads to a very thin tip of the ABH, making it very complicated if not impossible to manufacture. Improving this ABH property has been for the past decade an active field of research. Recently, the concept of a virtual acoustic black (VABH) has been proposed by the authors. The key idea of this approach is to implement digitally the mechanical impedance of the ABH. The virtual feature of this strategy enables the implementation of any kind of ABH (any dimensions, material). Setting the cut-off frequency to low values thus becomes possible. The VABH is implemented through the use of piezoelectric patches, making it very compact and autonomous. Experimental demonstration shows that the proposed idea is able to mitigate vibration below 100 Hz.

Simulation and characterization of an integrated MR damper with energy harvesting and embedded channels

Combined with two objectives of vibration reduction and energy harvesting, an integrated magnetorheological (MR) damper with energy harvesting and embedded channels is presented in this research. The effects of different structural parameters on the magnetic flux density and damping performance of the damping module are investigated using the finite element method. In addition, the effects of different frequencies, amplitudes, currents, and external resistances on the damping and energy harvesting characteristics of the proposed damper are experimentally studied. Simulation results demonstrate that the damping force first increases and then decreases with the increase of inner cylinder thickness and magnetic isolation height, increases with the increase of coil turns and current size, and decreases with the increase of outer cylinder thickness and magnetic isolation width. Simulation values of the damping force of the damping module are in good agreement with experimental data. Experimental results indicate that the damping force of the energy harvesting module drops as the external resistance rises. The output voltage of the energy harvesting module increases with the raise of external resistance. The average output power and the energy harvesting efficiency of the new damper reach 7.3 W and 53.5 % when A = 10 mm, f = 2 Hz, and R = 5 Ω.

Analysis of biomechanical passive synergistic vibration reduction inspired by the structure, morphology, nano-mechanics of the beetles’ hindwing

Using scanning electron microscopy (SEM), a small animal imaging system, and biological tissue sections, the relationships between the flapping vibrations in the hindwings of Trypoxylus dichotomus and their morphology, structure, and hemolymph dynamics were investigated. Based on these findings, a three-degree-of-freedom (3-DOF) model incorporating nano-mechanical properties was developed to investigate spanwise passive synergistic vibration reduction (PSVR) in the hindwing elements. To ensure precision, the Runge-Kutta and incremental harmonic balance (IHB) methods were employed for both solving and comparing solutions. Analysis of the spanwise force (FOX) signals confirmed the validity of the PSVR model. Parametric analysis revealed that reducing system mass and stiffness increased the resonance amplitude while shifting the resonance frequency in the opposite direction. The resonance frequency and flexible deformation amplitude of the hindwing system could be controlled by adjusting mass and stiffness within the synergistic framework. The mass and damping of the wing base, along with the stiffness of the wing membrane, were identified as critical factors in the system. This model provides valuable insights into the PSVR mechanism, potentially informing the design and manufacture of bionic flexible flapping wings.

The experimental research of which different types of impact signals affect the bifurcation chaos behavior of three-degree-of-freedom collision system

Abstract Collision is a faulty behavior in mechanical equipment, which greatly affects the safety of equipment. In this paper, aiming at the collision failures that are prone to occur in mechanical equipment, the nonlinear fault collision behavior of a class of three-degree-of-freedom collision systems is studied. A three-degree-of-freedom piecewise non-smooth collision experiment platform system has been established to facilitate further analysis of the bifurcations and chaos inherent to the bearings system. This analysis is conducted through the use of Poincaré mapping on the collision plane. The excitation signals employed, which include sinusoidal, triangular, and rectangular signals, result in the emergence of specific types and orders of bifurcation behaviours within the system, as evidenced by the establishment of a Poincaré mapping at the collision surface, and this is observed to occur as the vibration frequency increases. The characteristics of impact signals generated by force sensors and the influence of impact signal type on the system are investigated. The nonlinear impact behavior of three-degree-of-freedom collision systems provides a reliable foundation for the design, fault diagnosis, and theoretical guidance of large-scale high-speed rotating machinery, as well as technical support for safe and stable operation of high-speed rotating machinery, which is essential for failure analysis and vibration reduction in equipment.

Topological modes, vibration attenuation, and energy harvesting in electromechanical metastructures

The dynamics of topological boundary modes in both periodic and quasi-periodic electromechanical metastructures is investigated, with a focus on their applications to energy harvesting and vibration reduction. The metastructure analyzed in this study is based on a shunted array of piezoelectric patches, with electrical parameters modulated according to the 1D Aubry–André–Harper model. As a result of this modulation, a fractal spectrum is generated near the central frequency of the resonators, a hallmark of nontrivial topology that enables the emergence of digitally controllable edge states and ensuing localization phenomena at subwavelength frequencies. In this framework, a detailed analysis of the metastructure spectral characteristics is conducted to investigate the influence of the modulation parameters on mode localization, both at the boundaries and within the interior of the beam. Such localization effects are then studied in relation to the energy harvesting, attenuation, and wave transport capabilities of the system. These functionalities point toward the realization of self-powered structures with low frequency and digitally controllable vibration attenuation capabilities, and are considered of significant technological interest in applications involving elastic waves and vibrations, where the ability to precisely control and harness these phenomena could lead to innovative solutions in energy-efficient and adaptive systems.

Characteristic analysis of rain-wind induced stay-cable vibration based on friction damper in field observation

Abstract Both domestic and foreign scholars have developed various friction dampers with good characteristics. The primary types of friction dampers include conventional friction dampers, Pall friction dampers, Sumitomo friction dampers, and Centripetal friction dampers. The components of these dampers will slip or deform under load effect when the energy is consumed by friction. As the structural vibration period increases while the external energy input decreases, the vibration amplitude is reduced. This vibration reduction method is widely used in the automotive industry. Most of the hysteresis models of dampers are similar to rectangular shapes, making the selection of an accurate initial sliding force crucial for the rectangular hysteresis model. Based on the effective data collected from the field observation test, a self-made friction damper, which has a good vibration reduction effect, was used to observe rain-wind induced stay-cable vibration at Dongting Lake Bridge in Yueyang, Hunan Province. Accordingly, some suggestions are put forward for the research work on rain-wind-induced vibration.

PID Controller Parameter Tuning Based on a Modified Differential Evolutionary Optimization Algorithm for the Intelligent Active Vibration Control of a Combined Single Link Robotics Flexible Manipulator

This paper introduces some of the various techniques of vibration control and optimization for the purpose of vibration reduction and balancing. Here, in this research by comprising three of the most effective variational techniques now, a Modified Differential Evolutionary Optimization Algorithm (MDEOA) method is suggested to handle the challenge of adjusting the PID controller parameters for the Intelligent Active Vibration Control (IAVC) of a Combined Single Link Robotics Flexible Manipulator (CSLRFM) in order to reduce the undesired effects of vibration. The Crossover Probability Factor (CPF) as the Certain Ratio (CR) and the Mutation Factor (MF) of the algorithm are gradually altered during algorithm iteration to enhance the method's performance during optimization. On this foundation, the PID controller parameter tuning and the issue of CSLRFM mechanical vibrations are addressed using the MDEOA method. This research suggests an evolutionary algorithm that incorporates the variational techniques mentioned above, which will be combined by a certain ratio, and the specific computational procedure. In this strategy, a Strictly Bearish Distributed Exponential Function (SBDEF) has been used as the main target and the criteria and indicators for evaluating and measuring the optimal performance of differential evolution are the Integral Absolute Error (IAE) rate and the PID controller parameter values. According to simulation findings, the technique can be used to optimize the PID controller parameters settings for the IAVC of the CSLRFM and a reduction in the mechanical vibrations. Simulation results illustrate the effectiveness of the proposed MDEOA strategy which is significantly and quite satisfactory about 25 to 30 (%) better than comparing to the other algorithms in improvement stabilization and vibration control of CSLRFM.

Enhancing electric car lithium-ion batteries by using adaptive materials to improve heat transfer and reduce fatigue

The widespread adoption of electric vehicles (EVs) hinges on the efficiency and reliability of their battery systems. However, EV batteries still have many issues, mostly in terms of quantity, storage efficacy, charging speed, lifespan, and security, particularly, temperature variations, which can cause accidents that can lead to losses of products and persons. Hence, any advancement in the field of EV batteries would improve their performance and thus, boost daily usage of EVs that would reduce the pollution caused by traditional cars. Therefore, the main objective of this study focuses on improving the thermal and mechanical stability, energy storage efficiency, and safety of electric vehicle batteries by incorporating multifunctional materials, particularly phase-change materials (PCM) and shape memory alloys (SMA). By incorporating PCM, the thermal regulation of batteries is enhanced, resulting in better charge-discharge cycles, extended battery life, and reduced overheating risks, all of which contribute to increased safety. SMA integration, on the other hand, offers mechanical protection, flexibility in heat management, and resilience against thermomechanical fatigue, further improving battery longevity. Moreover, the incorporation of these adaptive materials not only boosts battery performance but also ensures that the materials can be seamlessly integrated without affecting the overall design or significantly increasing the weight of the battery. Thus, a systematic numerical study was conducted in order to adapt the multifunctional materials with each other and with EV battery systems. The study demonstrated a significant improvement in battery thermomechanical stability, leading to better storage performance, quality, and charging speed. Particularly, the findings showed a remarkable increase around 23: % in thermal stability duration, preventing excessive temperature variations, and an important reduction in mechanical vibrations around 79 %, which minimizes fatigue and enhances durability. Finally, the results revealed that the proposed adaptable materials are the most stable for car batteries even during fast charging while driving. These materials can also support alternative ways of charging, such as using solar sources.

Research of scale effect on propeller bearing force of a four-screw ship in oblique flow

To study the scale effect on propeller bearing forces in oblique flow, the propeller bearing forces of a fully appended four-screw ship that refers to a vessel propelled by four propellers are calculated and investigated. The findings reveal that scale effects in wake fields lead to an increase in the axial velocity of the propeller disk in the full-scale ship compared to the model, influenced by boundary layer flow. Moreover, asymmetric differences in the impact of oblique flow on the leeward and windward sides result in varied effects of positive and negative drift angles on the wakefield. The disparity in wake fields between inside and outside disks exacerbates unbalanced load distribution, with time-averaged loads showing an increase with drift angle for both propellers at full scale. Additionally, pronounced scale effects lead to variations in blade loads between model and full scale, with drift angles shifting the locations of single-blade load extremums. Unsteady bearing force components exhibit periodic fluctuations, with larger amplitudes at the blade passage frequency for the model scale propeller compared to the full scale, particularly evident under negative drift angles. The aforementioned findings can provide theoretical guidance for load balancing and vibration reduction of the four-screw ships.

HLSM-MIPV Algorithm of unbalance vibration suppression of dual-rotor in contra-rotating propfan

The inner and outer rotors of the contra-rotating propfan dual-rotor system, utilizing dual intershaft bearings, exhibit anisotropic support characteristics, whereas the vibration of the dual-rotor system is cross-coupled. This combination makes the identification of unbalanced responses and the efficiency of dynamic balancing challenging. To address this issue, this paper proposes a method for the dynamic balancing of the contra-rotating dual-rotor based on Harmonic Least Squares Method and Modified Initial Phase Vector (HLSM-MIPV). Firstly, a test bench for the contra-rotating dual-rotor system is constructed using two Micro-Electro-Mechanical Systems (MEMS) sensors. Secondly, unbalanced vibration vectors of the dual-rotor are identified using Harmonic Least Squares Method (HLSM). Thirdly, the Harmonic Component Method with the Modified Initial Phase Vector (MIPV-HCM) is introduced to balance the force and couple unbalance under anisotropic stiffness conditions. Finally, dynamic balancing tests on the test bench demonstrate that the MIPV-HCM method achieves an additional vibration reduction of 4 %–17 % compared to the traditional HCM.

Vibration Control for Laminated Composite Spherical-Cylindrical-Combined Shells: Theory and Experiment

Considering the structural damage and instability due to extensive vibrations, the present investigation focuses on the dynamic characteristics analysis and vibration control for aerospace structures such as rocket stages and aircraft cowling, modeled as laminated composite spherical-cylindrical-combined shells (SCCSs). The theoretical model of the SCCSs is established by a series of artificial connection and boundary springs. The proposed method’s validity is confirmed through finite element analysis and experimental validation. Nickel-titanium-steel wire ropes (NiTi-STs) are then introduced as a passive vibration control method for the SCCSs. Both circumferential and axial NiTi-ST laying schemes demonstrate good vibration control capabilities on the SCCSs. For similar lengths of NiTi-STs, the vibration control effect of circumferential laying schemes is superior to that of the axial one. Furthermore, the vibration control effect of the circumferential schemes is found to be dependent on the number and positioning of NiTi-STs. The influence of the NiTi-ST structural parameters on the vibration control performance is also analyzed; adjusting the structural parameters appropriately is helpful to improve the vibration reduction effect.

Enhancing visual seismocardiography in noisy environments with adaptive bidirectional filtering for Cardiac Health Monitoring

BackgroundWearable sensors have revolutionized cardiac health monitoring, with Seismocardiography (SCG) at the forefront due to its non-invasive nature. However, the substantial motion artefacts have hindered the translation of SCG-based medical applications, primarily induced by walking. In contrast, our innovative technique, Adaptive Bidirectional Filtering (ABF), surpasses these challenges by refining SCG signals more effectively than any motion-induced noise. ABF leverages a noise-cancellation algorithm, operating on the benefits of the Redundant Multi-Scale Wavelet Decomposition (RMWD) and the bidirectional filtering framework, to achieve optimal signal quality.MethodologyThe ABF technique is a two-stage process that diminishes the artefacts emanating from motion. The first step by RMWD is the identification of the heart-associated signals and the isolating samples with those related frequencies. Subsequently, the adaptive bidirectional filter operates in two dimensions: it uses Time-Frequency masking that eliminates temporal noise while engaging in non-negative matrix Decomposition to ensure spatial correlation and dorsoventral vibration reduction jointly. The main component that is altered from the other filters is the recursive structure that changes to the motion-adapted filter, which uses vertical axis accelerometer data to differentiate better between accurate SCG signals and motion artefacts.OutcomeOur empirical tests demonstrate exceptional signal improvement with the application of our ABF approach. The accuracy in heart rate estimation reached an impressive r-squared value of 0.95 at − 20 dB SNR, significantly outperforming the baseline value, which ranged from 0.1 to 0.85. The effectiveness of the motion-artifact-reduction methodology is also notable at an SNR of − 22 dB. Consequently, ECG inputs are not required. This method can be seamlessly integrated into noisy environments, enhancing ECG filtering, automatic beat detection, and rhythm interpretation processes, even in highly variable conditions. The ABF method effectively filters out up to 97% of motion-related noise components within the SCG signal from implantable devices. This advancement is poised to become an integral part of routine patient monitoring.

Particle damping equivalent method based on force chain for high frequency vibration reduction: Mechanism analysis and experimental verification

A particle damping equivalent method based on force chain is newly proposed for simulating the behavior of particle damper (PD) with higher accuracy. Compared with other existing equivalent methods, this method considers the contact between particles and evaluates the particle motion state. Firstly, the particle damping equivalent method based on the theory of force chain and contact model is proposed, and the simulation process of the equivalent method is described. Then, this equivalent method is adopted to simulate the high frequency vibration of pipe installed with PD using SAP2000 software. The simulated vibration response exhibits excellent agreement with experimental results, validating the effectiveness of the proposed equivalent method. Finally, based on the calculation results, it is observed that the particle motion state of the PD in the experiment is quasi-static. This further shows that the particle chain in the damper under high frequency vibration can ignore the wave propagation behavior, which aligns with the assumption of the particle contact model.

Local resonance metamaterial-based integrated design for suppressing longitudinal and transverse waves in fluid-conveying pipes

To solve the problem of low broadband multi-directional vibration control of fluid-conveying pipes, a novel metamaterial periodic structure with multi-directional wide bandgaps is proposed. First, an integrated design method is proposed for the longitudinal and transverse wave control of fluid-conveying pipes, and a novel periodic structure unit model is constructed for vibration reduction. Based on the bandgap vibration reduction mechanism of the acoustic metamaterial periodic structure, the material parameters, structural parameters, and the arrangement interval of the periodic structure unit are optimized. The finite element method (FEM) is used to predict the vibration transmission characteristics of the fluid-conveying pipe installed with the vibration reduction periodic structure. Then, the wave/spectrum element method (WSEM) and experimental test are used to verify the calculated results above. Lastly, the vibration attenuation characteristics of the structure under different conditions, such as rubber material parameters, mass ring material, and fluid-structure coupling effect, are analyzed. The results show that the structure can produce a complete bandgap of 46 Hz–75 Hz in the low-frequency band below 100 Hz, which can effectively suppress the low broadband vibration of the fluid-conveying pipe. In addition, a high damping rubber material is used in the design of the periodic structure unit, which realizes the effective suppression of each formant peak of the pipe, and improves the vibration reduction effect of the fluid-conveying pipe. Meanwhile, the structure has the effect of suppressing both bending vibration and longitudinal vibration, and effectively inhibits the transmission of transverse waves and longitudinal waves in the pipe. The research results provide a reference for the application of acoustic metamaterials in the multi-directional vibration control of fluid-conveying pipes.