Vibration Damping Performance Research Articles

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.

Research on Vibration Damping of Tuned Mass Damper for Wheeled Excavator

Background: When driving and working, the engine, working equipment and uneven road surface will cause severe vibrations to the wheeled excavator, which can affect efficiency and comfort. This paper discusses various patents and presents a new method of vibration reduction for excavators. Objective: The research aims to design the excavator's counterweight as a tuned mass damper (TMD) to reduce body vibration. Methods: The recent patents of TMD were investigated in this research. In this paper, the counterweight of the excavator is designed as a non-linear TMD system. The vibration models were established under the driving and crushing conditions, respectively. The vibration response of the vehicle body was calculated and analyzed through MATLAB/Simulink under driving and crushing conditions. Finally, the damping characteristics of the TMD system were discussed. Results: The vibration of the car body can be reduced by TMD. The improvement rates in vertical acceleration were 8.05%, 11.85% and 11.15% for the three classes of road surfaces for the driving conditions. The improvement rates of vertical accelerations for the three powers of crushing conditions are 16.18%, 18.32% and 23.48%, respectively. Conclusion: The vibration damping performance of the excavator was effectively improved by TMD in the main working conditions. The variation of body vertical acceleration with TMD parameters indicates the existence of optimal damping characteristics parameters for the TMD system at a fixed road surface and vehicle speed.

Research on dynamic characteristics of novel filled damping block mesh-type rail pads for heavy haul railways

Currently, the commonly used rail pads for heavy haul railways are grooved rubber rail pads (GRRP) and prismatic thermoplastic polyester elastomer (TPEE) rail pads (PTRP). However, the rail pad of the traditional structure has an obvious stress concentration when compressed and limited damping performance, which severely limits the service life of the rail pad. This study proposes a novel filled damping block mesh-type rail pad (NFDBMTRP) suitable for heavy haul railways. The rail pad has better damping performance than that of the traditional rail pad under the same stiffness condition. When the rail pad is under pressure, its hexagonal mesh structure can ensure that the stress distribution of the rail pad is uniform. Meanwhile, the damping block filled in the hexagonal mesh cavity can absorb part of the energy so that the overall stress level of the NFDBMTRP is small, which is beneficial for prolonging the service life of the rail pad. On the basis of the vehicle–track coupled dynamics theory, the C80 truck–track coupled dynamics calculation model was established, and a field test of the heavy haul railway was conducted. The time and frequency domain signals of the rail and sleeper acceleration obtained from the test were compared with those from the simulation to verify the accuracy of the dynamics model calculations. Under the same stiffness (70 kN/mm), the dynamic response differences in the four rail pads were compared and studied. The dynamic calculation results showed that the NFDBMTRP not only has smaller acceleration than that of the other three rail pads on the rail, sleeper, and car body but also has the smallest wheel–rail vertical force and derailment coefficient. This implies that improving the damping of the rail pad is beneficial for improving the safety and stability of train operation and has a certain protective effect on the under–track structure. To sum up, the NFDBMTRP has better structural properties and vibration damping performance compared with the traditional rail pad, and has broad application prospects in the heavy haul railway fastening system.

Vibration Characteristics of Shear Thickening Fluid-Based Sandwich Structures

The vibration attenuation mechanism of shear thickening fluid- (STF-) filled sandwich structures was investigated in this study. Structural equivalent damping, stiffness, and mass increased simultaneously with the increase in the volume fraction of shear thickening fluid. However, the damping ratio decreased and natural frequency increased with the increase in structural mass. Thus, the damping ratio was not a monotonically increasing function of the volume fraction of STF. A modified shear strain model of the damping layer was developed based on the following conditions: (1) under the condition of small strain, shear thickening fluid was regarded as linear viscoelastic material, and (2) the warpage of the sandwich beam was considered during deformation and the influence of STF on the shear strain of sandwich beam. According to the modified shear strain model of the damping layer, the shear thickening occurred at 1 Hz to 20 Hz during vibration. Therefore, the resonance point of the structure shifted to the left. The predictions were in excellent agreement with the experimental results. The results demonstrated that shear thickening fluid improved the vibration damping performance of the sandwich structure, while the thickening ability was not the higher, the better.

Tribological characteristics and mechanism of nitrile butadiene rubber coated with typical liquid lubricants

When marine stern shafts operate under low speed and heavy load conditions, the metal shaft and water-lubricated bearing will be in a state of boundary lubrication or even dry friction. Poor lubrication can cause severe wear and friction-induced vibration, endangering the stealth performance of underwater vehicles. In this study, several typical liquid lubricants, including liquid paraffin, tung oil (TO), dimethyl silicone oil (DSO), ionic liquid (IL), and hexamethylene diisocyanate (HDI) were selected as the surface coatings for nitrile butadiene rubber (NBR). Using a tribological test machine with a high-precision vibration acceleration sensor, as well as scanning electron microscopy (SEM) and other techniques, the tribological performance and mechanisms of the NBR samples coated with different lubricants were studied under various working conditions. The results showed that the liquid lubricant significantly reduced the coefficient of friction of the NBR at high rotational speeds by over 92.2%. The sample coated with HDI showed obvious tribochemical wear, and coating with the rest of the liquid lubricants decreased the specific wear rate of NBR. According to the friction-induced vibration signals, we found that an increase in loading aggravated friction-induced vibrations, and the vibrational energy was mainly concentrated in the low frequency range. The liquid paraffin and TO coatings barely changed the vibration characteristics of the NBR, while the other three lubricants produced more friction-induced self-oscillations. In conclusion, compared to the other liquid lubricants, TO exhibited the best tribological performance. The finding of this study further our understanding of the friction and vibration behaviours of polymer materials, providing a reliable basis for designing composite materials with good lubrication and vibration damping performance.

Fractional Order PID Control Based on Ball Screw Energy Regenerative Active Suspension

A ball screw type energy regenerative active suspension under fractional order PID control is proposed and studied in order to improve the vibration damping performance of the suspension. A mathematical model of the energy regenerative actuator is established, the energy recovery power at different frequencies is measured through experiments, and then the electromagnetic torque constant, representing the proportional relationship between the output torque and current of the motor, is calculated according to the experimental results. A mathematical model of the control circuit is established and the feasibility and the superiority of the fractional order PID control are verified by simulation and experiments. To achieve a better damping effect, the fractional order PID controller of the whole vehicle suspension system is parameterized using the Beetle Antenna Search (BAS) algorithm. The results showed that the mean energy recovery power of the actuator was about 3.5091 W at a vibration frequency of 11/6 Hz, and the electromagnetic torque constant of the motor was about 0.2885. The actuator control circuit was feasible, and the root mean square value of current deviation under fractional order PID control was 1.1158 mA, which was optimized by 9.40%, compared to the PID control. The BAS algorithm effectively realized the parameter tuning of the controller, and both the tuned PID and fractional order PID controllers, achieved optimization of suspension damping performance. The optimal value of the damping performance objective function under fractional order PID control was 0.3270, which was optimized by 62.93%, compared to the PID control. In addition, all suspension performance indices under fractional order PID control were optimized to a certain extent, compared with the PID control.

교량 바닥판의 다중모드 진동 저감을 위한 2자유도 진동흡진기

Vibrations that impact bridges need to be addressed because they can cause problems in terms of serviceability and structural safety. Therefore, the serviceability standards for vibration are considered by performing wind resistance design and loading tests. This study proposes a two-degree-of-freedom (2DOF) dynamic absorber that reduces the multi-mode vibrations of a bridge deck affected by wind load. The bridge decks have multi-mode vibration characteristics because various forces such as drag, lift, and moment are generated under the influence of wind loads. Therefore, a dynamic model is constructed and the parameters of the reduced model are used. In addition, the design formula for a single rigid 2DOF dynamic absorber is proposed to reduce vibrations occurring at two resonant frequencies acting on the bridge deck. Finally, the performance is confirmed by numerical simulations. In addition, it was shown that the vibration damping performance of the proposed dynamic absorber was affected by the radius of gyration as well as the mass ratio.

Theoretical and experimental study on vibration reduction and frequency tuning of a new damped-sleeper track

• A new elastic side-supporting long sleeper damping track (ESSDT) is proposed. • A vibration reduction and frequency modulation device (VRFMD) is applied to the ESSDT. • The vehicle-track coupled dynamics analysis is achieved by co-simulation. • The VRFMD can adjust natural frequency and improve dynamics performance of the ESSDT. In urban rail transit, it is important to reduce the train-induced vibration on ambient environment. To achieve this goal, a new elastic side-supporting long sleeper damping track (ESSDT) is proposed in this study. Besides, a novel vibration reduction and frequency modulation device (VRFMD) is also proposed to improve the vibration damping performance as well as structural stability of ESSDT. Based on the vehicle-track coupled dynamics model and the finite element model of ESSDT, dynamic characteristics of ESSDT are investigated theoretically. The influence of key dynamic parameters of VRFMD on the damping effect and stability of the track system are studied in detail. Further, a hammer test was conducted on a full-scale test rig of ESSDT with VRFMD. Test results validate the theoretical research results, which proves that both the vibration of track and the vibration transmitted to the foundation can be attenuated effectively due to the installation of VRFMD. The results show that the spring stiffness of VRFMD has great influence on the dynamic response to ESSDT. The natural frequency of ESSDT could be adjusted by modifying the parameters of VRFMD, which may provide a new approach to avoid wheel-rail contact resonance. Moreover, VRFMD may also be introduced to other types of track for the purpose of vibration reduction and frequency adjustment, such as floating slab track and ladder sleeper track.

Research on Dynamic Performance of CRTSⅢ Type Slab Ballastless Track under Long-Term Service.

To fill the blank in the research on the dynamic performance of track structure under long-term service, the dynamic response study of China Railway Track System Ⅲ type slab ballastless track (CRTSIII SBT) under the action of fatigue for 30 million times and the parting between track slab and self-compacting concrete (SCC) was carried out. By establishing the finite element model of the CRTSIII SBT structure and taking the stiffness change of isolation layer and fastener under fatigue state and the parting during service as the research objects, combined with the full-scale model test, the dynamic response amplitude and vibration law of track structure was analyzed based on the finite element model of axle falling test method. The results show the following: (1) Under the fatigue load, the acceleration of rail and base increases obviously, the longitudinal tensile stress of SCC surface decreases, the longitudinal tensile stress of base surface increases, and the vertical stress of each layer of track structure increases as well. (2) Under the action of the parting, the dynamic response of each structural layer increases, and the change of acceleration and stress of each layer under the action point of axle falling is the most obvious. (3) The fatigue load will weaken the vibration damping performance of the track, and the parting will continue to develop under the action of the falling axle, resulting in partial or total failure of the SCC layer. Both of them will aggravate the dynamic response of the track structure and affect driving safety, which should be paid attention to during maintenance.

Experimental and Numerical Research on a Pipe Element Passing through Bulkhead with Symmetrical Elastic Installation

To reduce the transmission of vibration energy from the ship’s pipeline to the bulkhead, a novel all-metal pipe element passing through the bulkhead with symmetrical elastic installation was proposed in this paper. A metal bellow, a multi-layer thin-walled symmetrical structure, was used as an elastic element and entangled metallic wire materials (EMWM) were used as a damping element. The insertion loss was adopted to evaluate the vibration damping performance. The results show that compared with the pipe element passing through the bulkhead with rigid installation, the vibration damping performance of the pipe element passing through bulkhead with symmetrical elastic installation can significantly isolate the vibration transition, and the maximum average insertion loss in each direction can reach 25.4 dB. A thermal-vibration joint test system of the pipe element passing through the bulkhead was built. A series of comparison experiments were carried out to investigate the influence of temperature, symmetrical measure points, and exciting directions on the vibration response transmitted to the bulkhead. Therefore, the vibration damping performance was verified.

Microstructural modeling of porous foams and study on damping performance

With the electrification of power sources, vibration and noise caused by internal combustion engines have been reduced. However, road noise caused by uneven road surfaces has become relatively more noticeable. At the same time, the demand for At the same time, the demand for lightweight vehicles is becoming more stringent from the standpoint of improving fuel efficiency and electricity costs. Road noise noise is generated by the lower part of the vehicle body, and it is necessary to efficiently suppress vibrations from floor panels and other parts of the vehicle. The floor panels and other parts are required to suppress vibrations efficiently. In this study, we focus on porous foams, which are widely used as soundproofing materials. The microstructure that improves the vibration suppression performance of steel panels is The homogenization method based on the asymptotic expansion method is used to investigate the microstructure that improves the vibration damping performance of steel panels.

Ability of vibration control using rubberized concrete for tunnel invert-filling

Crumb Rubber Concrete (CRC) tunnel invert-filling is made of the rubberized concrete using waste rubber as aggregate. In this paper, the dynamic characteristics of the CRC tunnel invert-filling was studied. Firstly, the mesoscale specimen models of rubberized concrete were constructed to obtain the elastic modulus, Poisson's ratio, and damping ratio of the rubberized concrete at the macro scale. Secondly, a macroscale model of CRC tunnel invert-filling, which was verified by the experiment, was established. Based on this, the dynamic characteristics of the CRC tunnel invert-filling with different rubber content (0%, 5%, 10%) were analyzed. The results show that the CRC tunnel invert-filling can effectively attenuate the vibration acceleration transmitted to the tunnel. Furthermore, compared with 0% rubber content, (1) the effective values of vibration acceleration with rubber content 5% and 10% are reduced by 4.2% and 9.2%, respectively. (2) the tunnel invert-filling of rubberized concrete has better vibration damping performance in the central frequency range of 1 ∼ 10 Hz and 20 ∼ 63 Hz, and the maximum insertion loss is 2.1 dB. In general, 10% rubber content is the best compared with 0% and 5%.

Structural Design of Extruded Profiles Based on Simulation

In this paper, through the introduction of ABH related theory, a variety of optimized structures are established and compared. By changing the layout of holes in extruded profiles, the vibration characteristics of extruded profiles are studied by using the control variable method. It is found that for single extrusion profile, the through hole (the radius is 8mm to 10mm, the chamfer is 30 degrees) compared with the structure without holes, the natural frequency of the structure is increased by 7Hz from the first order to 20 Hz from the seventh order. For the spliced extruded profiles, the wedge-shaped hole structure with 8mm to 10mm has better vibration damping performance. The application of ABH structure can effectively improve the vibration characteristics of extruded profiles.

SMC/TPE bi‐layer configurations for structural vibration damping applications

AbstractSheet molding compounds (SMCs) have considerable potential as lightweight alternative to traditional materials used in automotive components. However, despite their outstanding mechanical properties, their vibration damping characteristics are often relatively poor for several applications. Therefore, enhancing the vibration damping capability of SMCs represents a field with increasing interest. Application of viscoelastic layers to high stiffness materials, such as SMCs, represents an effective approach to add vibration damping functionalities to lightweight structural components. In this work, the incorporation of thermoplastic elastomers (TPEs) is studied as a novel strategy to enhance the structural vibration damping capability of SMCs. Several types of SMC and TPEs have been considered and the effect of TPE‐SMC thickness ratio on the damping and stiffness properties is investigated. The viscoelastic properties and vibration damping performance were evaluated by dynamic mechanical analysis. The effect of TPE addition on stiffness was studied by three‐point bending. Results reveal the potential of the incorporation of thin TPE layers as cost‐effective strategy to enlarge the vibration damping efficiency of SMCs while maintaining their overall high stiffness. It is expected that the bi‐material configurations presented in the current study will contribute to advance the development of new lightweight multi‐functional solutions for modern transport applications.

Optimal design of helical flute of irregular tooth end milling cutter based on particle swarm optimization algorithm

Due to the variable pitch angle and helix angle of the irregular tooth end milling cutter, the mass of the integral end milling cutter is eccentric, and the high stability and precision design of the irregular tooth end milling cutter is still a challenge. Aiming at the influence of dynamic balance of irregular tooth end milling cutter which can not be ignored in high-speed milling, the parameterized design of radial section of irregular tooth end milling cutter was carried out. Based on the space transformation law of the centroid of helical flute, a new method for calculating the centroid coordinate of end milling cutter was put forward, and a general mathematical model of eccentricity of integral end milling cutter was given. It was proved that this model could accurately calculate the centroid position and eccentricity of the end milling cutter. The influence of pitch difference angle and helix difference angle on eccentricity of end milling cutter was studied and analyzed. The particle swarm optimization (PSO) algorithm was creatively applied to optimize the helical flute shape of the end milling cutter, the curvature radius of helical flute curve is optimized, so that the centroid coordinate is infinitely close to the origin of coordinate. The number of iterations was set to 200. In the 32nd iteration, the result approached to infinitesimal, the final function converged, and obtained the groove curvature radius of the milling cuter with the smallest eccentricity. The optimized eccentricity of the end milling cutter is infinitesimal, which can make the vibration damping performance of the end milling cutter be fully developed. On the basis of ensuring the same cutting performance, the cutting tool unbalance was effectively reduced and the dynamic performance of milling cutter was further improved.