Vibration Damping Performance Research Articles

Preparation and energy absorption of flexible polyurethane foam with hollow glass microsphere

This paper presents the preparation of a partially open-cell and partially closed-cell flexible polyurethane foam material (flex-PUF), which exhibits improved cushioning performance compared to conventional protective materials. Hollow Glass Microspheres (HGM) were used as a filling material to enhance the compressibility of the material. In order to investigate the effects of HGM on the multi-impact protection and vibration damping performance of flex-PUF with different thicknesses, flex-PUF samples filled with varying volume fractions of HGM were subjected to multi-impact testing and dynamic viscoelasticity experiments. The destructive mechanism of HGM under impact was observed using scanning electron microscopy (SEM). The experimental results revealed that, under the same impact energy conditions, filling flex-PUF with HGM reduced the maximum impact displacement while enhancing energy absorption, although at the expense of cushioning performance. As the number of impact increases, the stiffness of flex-PUF decreased. In the vibration experiments, as the frequency increased, the proportion of flex-PUF’s viscous damping energy dissipation decreases.

Experimental Evaluation of a Granular Damping Element.

Due to their advantages-longer internal force delay compared to bulk materials, resistance to harsh conditions, damping of a wide frequency spectrum, insensitivity to ambient temperature, high reliability and low cost-granular materials are seen as an opportunity for the development of high-performance, lightweight vibration-damping elements (particle dampers). The performance of particle dampers is affected by numerous parameters, such as the base material, the size of the granules, the flowability, the initial prestress, etc. In this work, a series of experiments were performed on specimens with different combinations of influencing parameters. Energy-based design parameters were used to describe the overall vibration-damping performance. The results provided information for a deeper understanding of the dissipation mechanisms and their mutual correlation, as well as the influence of different parameters (base material, granule size and flowability) on the overall damping performance. A comparison of the performance of particle dampers with carbon steel and polyoxymethylene granules and conventional rubber dampers is given. The results show that the damping performance of particle dampers can be up to 4 times higher compared to conventional bulk material-based rubber dampers, even though rubber as a material has better vibration-damping properties than the two granular materials in particle dampers. However, when additional design features such as mass and stiffness are introduced, the results show that the overall performance of particle dampers with polyoxymethylene granules can be up to 3 times higher compared to particle dampers with carbon steel granules and conventional bulk material-based rubber dampers.

Reducing vibration and noise in honeycomb structure applied to automobile integrated water tank

This work uses modal acoustic transfer vector (MATV) technology in conjunction with vibration response analysis to determine optimal target optimization parameters for automobile integrated water tanks. The effects of square and hexagonal reinforcement honeycomb structures on the vibration damping performance of water tanks are analyzed, using an untreated smooth plane as a reference object. The study investigates the effects of honeycomb height, honeycomb length, and honeycomb thickness on the tank’s vibration damping performance. The results indicate that a hexagonal structure is more effective than a square structure in improving structural stiffness and reducing structural vibration. The height of the honeycomb structure is particularly effective in suppressing normal vibration of the structural surface, especially when the height exceeds 8 mm. A response surface model is developed based on the edge length, wall thickness, and height of the honeycomb, following the Box-Behnken central combinatorial test design principle. Considering the effect of interference of additional parts, the noise reduction is found to be most effective with a honeycomb side length L = 12 mm, height H = 4.91 mm, and wall thickness T = 2.5 mm. These parameters can be a guide for creating a new honeycomb reinforcement structure to better achieve vibration and noise reduction in automobile water tanks.

Parameter Analysis of Vibration Damping and Energy Harvesting Performance of Bionic Suspension

The traditional damping structure usually transfers the vibration energy into heat, dissipated and without harvesting. But for harsh environments, such as military activities and lunar probe patrols, the vibration energy can be extracted, and realize the purpose of self-power condition monitoring. In this paper, a bionic suspension with energy-harvesting property is proposed based on bionic configurations. The bionic suspension adopts a symmetrical three-link arrangement to simulate the arrangement of bones, and a horizontal spring to simulate muscles. The micro-generator embedded in the knee joint provides the main damping force for the overall structure and also plays a role in harvesting energy. The dynamic equation and virtual prototype model are established, and the effects of parameter changes on the performance of vibration reduction and energy harvesting are analyzed, and the relationship between the two is revealed. The results show that the parameters to achieve their respective optimal performance are not consistent in the trend, though it is difficult to obtain the best performance of both, it can be designed according to the specific functions to be satisfied. This structure can be utilized as a general model for vibration reduction and energy harvesting scenarios, providing new ideas for self-powered sensing and condition monitoring configurations.

Impact of speed and axle load on the static and dynamic mechanical behavior of the ballast bed laying under sleeper pads

With the evolution of railway infrastructure towards accommodating higher speeds and heavier loads, the under sleeper pad (USP) has emerged as a critical component in mitigating the deterioration of the ballast bed and reducing maintenance requirements. This study aims to enhance the understanding of the suitability of the USP for railway lines and to investigate the static and dynamic mechanical behaviors of the ballast bed (with USP) under the train load. To achieve this, the study conducts on-site tests and employs the discrete element method-multi-flexible body dynamics (DEM-MFBD) coupling analysis to develop a three-dimensional high-fidelity model of the ballast bed (with USP). This comprehensive analysis assesses the impact of varying train speeds and axle loads on the mechanical properties of the ballast bed with the USP, integrating both macroscopic and microscopic perspectives. The results show that there is an 8.54% reduction in longitudinal resistance of the ballast bed (with USP) compared to the ballast bed (without USP), yet it still fulfils the requirements of heavy railway lines. The ballast bed (with USP) exhibits significant improvements in vibration-damping performance, with the wheel-rail vertical force showing a reduction of 8.71% relative to the ballast bed (without USP). This suggests a potential extension of the track structure's lifespan. An increase in train speed markedly influences the vibration levels of the ballast bed (with USP), leading to an increase in ballast bed acceleration by 119.39%. The increase in train axle load demonstrates a minor effect on the plastic deformation of the ballast bed, indicating the ballast bed (with USP)'s capability to accommodate heavier axle load trains.

Simulation Study on the Influence of Grain Operation Conditions on the Dynamic Characteristics of Vehicle Body based on RecurDyn

At present, the grain storage depot has introduced the warehouse closing vehicle to replace the manual grain surface leveling operation. Aiming at the problems of subsidence, vibration and slipping when the warehouse car walks on the grain surface, the multi-body dynamics simulation is carried out for the four complex working conditions and load conditions of the car body in the grain depot environment, including straight running, turning, tilting and obstacle crossing, and its driving dynamic characteristics are analyzed. It can be seen from the simulation results that in the turning condition, the required driving force is the largest, the sliding condition is the most serious, the sinking degree is the deepest, and the stability is the worst. The driving dynamics of the clearance car will change suddenly when entering and leaving the pit under the obstacle crossing condition. Through the dynamic simulation results, the change law of the driving dynamic characteristics of the clearance car is summarized, and the vibration damping performance, adhesion performance and Through performance and work efficiency, it provides a theoretical basis for vehicle body design and optimization.

Study on vibration suppression of an aero-engine rotor system with adjustable oil film thickness driven by piezoelectric actuator through critical speed

The squeeze film damper (SFD) is difficult to meet the vibration control requirements of the rotor at both the critical speed and other rotor speeds at the same time due to the fixed structural parameters. The control method of piezoelectric ceramic actuator (PZT) actively changing the SFD oil film gap is proposed to suppress the critical amplitude of the rotor system. The dynamic model of the rotor system with PZT is established. The mechanical controllable characteristics of SFD are revealed, and the vibration damping performance of the controllable SFD (CSFD) is studied at critical speed. Both experiment and theory show that the proposed method can effectively suppress the critical amplitude of the rotor system with different imbalance.

Study on the vibration reduction characteristics of shock absorber throttle orifice in tractor suspension

The hydraulic shock absorber of a certain tractor suspension system is analyzed to determine the influence of the cross-sectional area ratio of the throttling holes of the restoration valve and the compression valve on the vibration damping performance of the whole vehicle, using a new method of machine-hydraulic co-simulation. First, the AMESim model of the hydraulic shock absorber is established, and the Kriging model is used to approximate the parameters of the AMESim hydraulic shock absorber model; the multi-island genetic algorithm and the gradient descent algorithm are used to obtain the three scenarios in which the cross-sectional area ratios of the throttle orifices of the same equivalent damping coefficients are greater than, equal to, or less than one. Then, a co-simulation model of 1/4 vehicle Recurdyn/AMESim and a co-simulation model of the whole vehicle with 162 degrees of freedom were established. The result show that, compared with the traditional method, this machine-hydraulic co-simulation method improves the calculation accuracy, calculation speed, and co-simulation model parameter accuracy. For low-speed conditions, when the throttle orifice area ratio equals 0.32, the minimum vehicle body center acceleration (root mean square value equal to 1.78 m/s2) is achieved. For high-speed driving conditions, when the throttle orifice area ratio is approximately 3.1, the minimum vehicle body center acceleration (root mean square value equal to 3.52 m/s2) is achieved.

Design and Biomechanical Properties of Symmetrical Lumbar Fusion Cage Based on Lightweight Titanium Alloy Flexible Microporous Metal Rubber

In recent years, the incidence rate of lumbar diseases has been progressively increasing. The conventional lumbar fusion cages used in existing lumbar interbody fusion surgery are not able to take into account the multiple characteristics of cushioning, vibration reduction, support, cell adhesion, and bone tissue growth. Therefore, in this work, based on the CT data of a lumbar intervertebral disc plain scan, a combined symmetric lumbar fusion cage structure was innovatively designed. The core was made of lightweight TC4 medical titanium alloy flexible microporous metal rubber (LTA-FMP MR), and the outer frame was made of cobalt–chromium–molybdenum alloy. Its comprehensive biomechanical performance was comprehensively evaluated through finite element simulation, static and dynamic mechanics, and impact resistance tests. The three-dimensional model of the L3/L4 lumbar segment was established by reverse engineering, and a Mises stress analysis was conducted on the lumbar fusion cage by importing it into Ansys to understand its structural advantages compared to the traditional lumbar fusion cage. Through static experiments, the influence of the internal nucleus of a symmetrical lumbar fusion cage with different material parameters on its static performance was explored. At the same time, to further explore the superior characteristics of this symmetrical structure in complex human environments, a biomechanical test platform was established to analyze its biomechanical performance under sinusoidal excitation of different amplitudes and frequencies, as well as impact loads of different amplitudes and pulse widths. The results show that under different amplitudes and frequencies, the lumbar fusion cage with a symmetrical structure has a small loss factor, a high impact isolation coefficient, and a maximum energy consumption of 422.8 N·mm, with a maximum kinetic energy attenuation rate of 0.43. Compared to existing traditional lumbar fusion cages in clinical practice, it not only has sufficient stiffness, but also has good vibration damping, support, and impact resistance performance, and has a lower probability of postoperative settlement, which has broad application prospects.

Bio-inspired metallic cellular material with extraordinary energy dissipation capability

Graphene coating on the skeleton of porous material opens the door to simply achieving high-performance composites. In this study, relying on the adhesive properties of polydopamine (PDA), PDA modified reduced graphene oxide (PDA-rGO) is adhered to the skeleton of nickel foam, of which the mechanical properties as well as the vibration damping and sound absorption performances are investigated. The mechanical test results reveal that the existence of coating leads to 240% and 59% increments of the compressive modulus and the yield strength, respectively. The enhancement of dynamic mechanical properties is also verified by dynamic mechanical analysis (DMA). Moreover, in DMA tests, the loss factors of nickel foam coated with PDA-rGO are found to achieve up to 170% growth, and show excellent stability with increasing temperature, indicating the reliability of loss factor enhancement in harsh environment. The superior vibration damping performance of nickel foam coated with PDA-rGO is further confirmed by vibration tests. Furthermore, the coating is found to effectively boost the flow-resistance and improve the sound absorption capability of nickel foam in turn, this synergy results in a significant increase in the noise reduction coefficient for up to 73.3%. Hence, adhering PDA-rGO to nickel foam in the present study provides a promising strategy for the development of multi-functional and versatile metallic foam.

Design of smart sandwich structures enhanced by multi-functional shear thickening fluids (M−STFs): Anti-vibration and electrical conductivity

This study investigates a novel concept of integrating multi-functional shear thickening fluids (M−STFs) into the core layer of a sandwich composite consisting of polyvinyl chloride (PVC) foam and aluminum face sheets to enhance the vibration damping of the structure. First, high-performance STF (60 wt% SiO2) was produced and M−STFs were created by gradually adding multi-walled carbon nanotubes (MWCNTs) up to 1.5 wt%. The percolation threshold range was obtained and the effects of increasing MWCNTs up to 1.5 wt% to STF on reducing electrical resistance and improving rheological properties were investigated. Secondly, sandwich structures consisting of aluminum face sheets and PVC foam core layers were made. The smart nanofluids STF and M−STFs were added to sandwich structures through the grooves created in the PVC foam core. Six different configurations were designed to investigate the effects of adding STF and M−STFs on the vibration damping performance of the sandwich structures. The model analysis results showed that the M−STFs integration into the core layer of designed sandwich structures significantly enhances the damping ratio of the structures as well as provides a higher stiffness coefficient. It was observed that the sandwich structure filled with 1.0 wt% MWCNT exhibits the highest damping ratio and stiffness.

Equilibrium Analysis and Simulation Calculation of Four-Star Type Crank Linkage Mechanism

Unbalanced inertia force is inevitably generated during the operation of crank linkage. It is one of the main excitation sources of air compressor vibration and the focus of managing air compressor vibration noise. In this regard, this paper studies the variation law of inertia force in the four-star type crank linkage mechanism. Certain balancing methods are used to reduce the unbalanced inertia force. Firstly, we present a comparison of perfect and partial balanced problems of crank linkage inertia forces. Then, using the ADAMS software multibody dynamics calculation method, the balancing mass is numerically calculated to optimize the design of the balancing mass for partial balancing of inertia force. Next, the influence law of piston mass asymmetry on the force of crankshaft revolving pair is studied. Lastly, two new types of four-star type crank linkage mechanism are proposed from the viewpoint of completely balanced inertia forces and moments of inertia. The results show that the perfectly balanced inertia force is better than the partially balanced inertia force in terms of a balancing effect. The parametric design of ADAMS software is more efficient and can get the best quality quickly. The design of perfectly balanced inertia force will increase the length and complexity of the crankshaft, while reducing the structural strength. The research results of this paper are important for improving the vibration damping performance of marine air compressors.

Design of a Functionally Graded Material Phonon Crystal Plate and Its Application in a Bridge

In order to alleviate the structural vibrations induced by traffic loads, in this paper, a phonon crystal plate with functionally graded materials is designed based on local resonance theory. The vibration damping performance of the phonon crystal plate is studied via finite element numerical simulation and the band gap is verified via vibration transmission response analysis. Finally, the engineering application mode is simulated to make it have practical engineering application value. The results show that the phonon crystal plate has two complete bandgaps within 0~150 Hz, the initial bandgap frequency is 0.00 Hz, the cut-off frequency is 128.32 Hz, and the internal ratio of 0~100 Hz is 94.13%, which can effectively reduce the structural vibration caused by traffic loads. Finally, stress analysis of the phonon crystal plate is carried out. The results show that phonon crystals of functionally graded materials can reduce stress concentration through adjusting the band gap. The phonon crystal plate designed in this paper can effectively suppress the structural vibration caused by traffic loads, provides a new method for the vibration reduction of traffic infrastructure, and can be applied to the vibration reduction of bridges and their auxiliary facilities.

Self-tuning vibration reduction study of magnetic fluid rolling-ball damper based on PSO-FUZZY-PID

For towering structures under complex time-varying excitation, the tuned magnetic fluid rolling-ball dampers (TMFRBD) cannot achieve self-tuning damping. In this paper, considering the operating characteristics of the TMFRBD, a damper self-tuning control algorithm, namely particle swarm optimization (PSO)-FUZZY-PID, is proposed for real-time adjustment of the intrinsic frequency of TMFRBD, which can greatly improve the damping effect, namely self-tuning magnetic fluid rolling-ball dampers (STMFRBD). Firstly, the equivalent dynamics model of the damping system is established, deriving the structural dynamic amplitude response as a function of the excitation frequency to structural frequency ratio. Different frequency tracking schemes of the damper are compared and analyzed. Then magnetic field simulations and magnetic fluid magnetic property measurements are performed for the dampers, respectively. Secondly, the self-tuning PSO-FUZZY-PID control algorithm is designed to improve the damping performance of STMFRBD under time-varying excitation by optimizing factors of the FUZZY-PID controller with PSO. To confirm the effectiveness of the damper self-tuning control algorithm, the frequency tracking of dampers with different control algorithms under time-varying excitation is compared. The results show that the damper’s frequency can be tuned quickly and accurately tracking excitation frequency by PSO-FUZZY-PID. Finally, the simulation and experimental results of STMFRBD and passive mass damper (PMD) under different loads are analyzed, and the structural amplitude response is analyzed using the Hilbert-Huang transform (HHT). In addition, the damping of STMFBD and TMFBD under different loads is compared. The results show that STMFRBD has better vibration-damping performance than PMD and TMFRBD.

Design of novel two-dimensional single-phase chiral phononic crystal assembly structures and study of bandgap mechanism

In this paper, novel two-dimensional single-phase three-ligament, four-ligament and six-ligament chiral structure models are proposed. The advantage is that it is easy to manufacture with few components, has good sound insulation and vibration damping performance, and is more practical. The dispersion information of the structure is calculated by combining Bloch's theorem and the finite element method. By varying the geometric parameters of the new structural single-cell and simulating the vibration transmission of the finite period structure to check the vibration suppression capability of the optimized structure. Three combined structures were constructed to compare their energy band properties with the base structure. The wave propagation characteristics within the combined structure are also analyzed by comprehensive means. It is shown that the optimized structure has a significantly lower bandgap down to below 1 kHz and a significantly wider bandgap width up to 3.6 kHz. The combined structure can open up a wider omnidirectional bandgap for multi-frequency and broadband vibration attenuation. The flexibility of the structure combination gives it a large potential for use, providing a new solution for broadband and multi-frequency vibration and noise reduction, while plane wave analysis provides theoretical support for structural optimization.

On the Vibration-Damping Properties of the Prestressed Polyurethane Granular Material

Granular materials promise opportunities for the development of high-performance, lightweight vibration-damping elements that provide a high level of safety and comfort. Presented here is an investigation of the vibration-damping properties of prestressed granular material. The material studied is thermoplastic polyurethane (TPU) in Shore 90A and 75A hardness grades. A method for preparing and testing the vibration-damping properties of tubular specimens filled with TPU granules was developed. A new combined energy parameter was introduced to evaluate the damping performance and weight-to-stiffness ratio. Experimental results show that the material in granular form provides up to 400% better vibration-damping performance as compared to the bulk material. Such improvement is possible by combining both the effect of the pressure-frequency superposition principle at the molecular scale and the effect of the physical interactions between the granules (force-chain network) at the macro scale. The two effects complement each other, with the first effect predominating at high prestress and the second at low prestress. Conditions can be further improved by varying the material of the granules and applying a lubricant that facilitates the granules to reorganize and reconfigure the force-chain network (flowability).

Study on the effect of curved fiber laying angle on the vibration free attenuation of composite laminates

Firstly, three groups of fiber curve laminates with different numbers of layers and different fiber curve angles were designed and prepared. A cantilever plate free vibration test was used to analyze the influence of the fiber curve angle on the vibration free attenuation characteristics of the laminates. The three groups of contrast test results show that the fiber curve angle has a significant effect on the loss factor of the laminate structure. When the angle change of the fiber curve was ±<45|60>, the loss factor of the laminates reached the maximum value, and the vibration damping performance of the laminates was the best. Secondly, modal tests were carried out on the laminates, the modeling and simulation of the variable stiffness laminate were completed, and the influence of the fiber curve angle on the natural frequency of the laminate was explored. The results showed that when the number of laminate layers was the same, the natural frequencies of the laminates first increased and then decreased with an increase in the fiber curve angle. The first three natural frequencies of the laminates reached the maximum value when the fiber curve angle was ±<45|60 > or ±<60|75>. Finally, it is concluded that when the fiber curve angle of the laminates varies between ±<45|60>, the damping ratio and the first three natural frequencies of the laminates reach the maximum value, and the vibration damping performance is the best.

Evaluation of flow-induced vibration suppression performances of magneto-rheological damping pipe clamp using PID algorithm

In order to suppress the low-frequency flow-induced vibration of fluid conveying pipeline, this paper develops a magnetorheological damping (MRD) pipe clamp due to its simple structure and strong dynamic adjustability. The mechanical dynamic model of MRD pipe clamp is established, and the vibration control algorithm based on PID is simulated. Comparison analysis on the vibration damping performance of the MRD pipe clamp under uncontrol, passive control, and PID control are conducted. The damping performances of MRD pipe clamp are tested under uncontrol, passive control, and PID control algorithm. The experiment results exhibited that the attenuation rate of each axial displacement and acceleration of pipe system using PID algorithm were more than 80% under sinusoidal excitation force of 600 N and excitation frequency of 2.5 Hz. The experiment results have verified the correctness of the simulation analysis in terms of value and trend. This research will provide the guide for the design and engineering application of MRD pipe clamp system.

Development of a Novel Seat Suspension Based on the Cubic Stewart Parallel Mechanism and Magnetorheological Fluid Damper

To alleviate the impact and vibrations to a driver in multiple directions during the driving of non-road vehicles, the authors of this paper proposed a multi-degree-of-freedom (MDOF) seat damping suspension that was based on the cubic Stewart mechanism and magnetorheological fluid (MRF) damper. A kinematics analysis of the cubic Stewart mechanism was carried out. The relative motion velocity of each leg of the Stewart mechanism was calculated from the center velocity of the upper and lower platforms, according to a reverse kinematics equation. Furthermore, forward and inverse dynamic models of the MRF damper were established, which laid the foundation for semi-active control of the seat suspension. Finally, a semi-active control method for multidimensional damping based on the optimized fuzzy skyhook control method was proposed. The research results showed that using this method could simultaneously improve the vibration damping performance of a seat suspension in the vertical, horizontal, and roll directions.

Active vibration control for high‐rise buildings using displacement measurements by image processing

This study aims to develop a high-performance active mass damper (AMD) for super high-rise buildings with a low natural frequency. Conventional AMDs utilize accelerometers to control vibration. However, those AMDs cannot sufficiently damp the vibration because the accelerometer sensitivity is low in a low-frequency band (e.g., the natural frequency of high-rise buildings). Under these circumstances, this study proposes the measurement of vibration displacements using cameras and an image processing technique, called template matching, instead of accelerometers. The measurement accuracy in the low-frequency band was evaluated by comparison to that of the accelerometer. The results indicate that the proposed method achieved a higher measurement accuracy compared to the accelerometers in the low-frequency band. One problem when applying the displacement measurement using image processing to the vibration control is time delay with calculation. We solved this problem using the Padé approximation. Finally, real-time hybrid tests attained with a combination of real-time simulation and experiment were conducted. The results confirmed that the proposed method reduced the first resonance peak value by 24% in the low-frequency band compared with the accelerometers. In addition, it can prevent the degradation of the vibration damping performance of the higher vibration modes (i.e., spillover phenomena) caused by acceleration control. The proposed method contributes to the development of a novel AMD that suppresses the shaking of super high-rise buildings.