Performance Of Damper Research Articles

Practical negative stiffness device with viscoelastic damper in parallel or series configuration for cable damping improvement

Negative stiffness mechanism has been found able to improve damping performance of dampers on a stay cable which otherwise is limited by the damper installation distance from a cable end. This study provides a practical negative stiffness device (NSD) with adjustable negative stiffness and experiments are performed to validate the negative stiffness effect. The NSD is then combined with a viscoelastic damper in parallel or series for cable damping improvement. Explicit design formulas are derived for optimal design with a target enhancement effect in damping considering the damper described respectively using the Kelvin model and the linear hysteretic damping model. The formulas are verified by analytical and numerical solutions. Parametric analyses show damping enhancement effects of the NSD and it is found more efficient when combined with a damper in series because both deformation amplitudes of the damper and the NSD are further increased in this configuration. Subsequently, case studies are carried out based on two cables of the Sutong Bridge respectively with a shear-type viscous damper and a high damping rubber damper. The results show that the designed NSD can fulfill practical requirements. Particularly, a 100% increase in damping can be achieved by the presented NSD when combined with the damper installed on a cable of 546.9 m long.

A voltage waveform design method for shortening current response time of a coil

SummaryCoils are widely used in magnetorheological dampers, solenoid valves, and electron guns, where a quick response of the magnetic induction to the excitation voltage is needed. To achieve a quick response, the response time of the magnetic induction relative to the current and that of the current relative to the voltage should be shortened as much as possible. The latter is dominant in the total response time and can be shortened by using voltage control with an increased resistance or current control. The current time responses of the Helmholtz coils based on voltage control with an increased resistance and current control are measured. The results indicate that the current response times of the coils based on voltage control with resistances of 23.7 and 162 Ω and current control with a resistance of 23.7 Ω are 235.3, 42.3, and 62.1 μs, respectively. The current time responses of the voltage control are smooth, while those of the current control have large oscillations. Based on Kirchhoff's equilibrium equation, an overshoot voltage waveform design method is proposed to shorten the current response time and eliminate the current oscillations. The experimental results show that the current time response is smooth, and the current response time can be shortened by 91.8%, 54.4%, and 68.9% in comparison with those of the former three control cases. The demonstration experiments of the effect of the different control methods on the electron‐beam scanning path and hot spot distribution show that the scanning path and dwell duration are closer to the expected ones with the proposed method. The proposed method is of great value for improving the damping performance of a magnetorheological damper, the accuracy of the fluid injection of a solenoid valve, and the accuracy of the electron‐beam thermal assessment.

Development of MR fluid assisted novel vibration damping fixture for milling machine

Chatter occurs in all metal cutting process and it is an important factor that causes uneven tool wear and reduced tool life resulting in poor surface finish of work piece. It even causes geometrical inconsistencies and poor surface finish. It can lead to higher costs, delayed deliveries and even loss of orders due to poor quality of the machined component. To reduce and control the tool vibration in metal cutting it is necessitating that to develop a clamping method to improve the vibration damping capability and improves the machining conditions. To cater this need design and development of Magnetorheological (MR) fluid assisted novel vibration damping fixture designed. The application of MR damper assisted fixture in milling machine is considered to be a solution for better vibration control and surface finish. From the experimental investigation it was evident that MR damper performance depends on parameters like suspended fluid, density, reaction time, particle size, maximum yield stress. The viscosity of the MR fluid depends on the intensity of magnetic field applied. Coil orientation, number of turns, current, gap between cylinder and piston are important parameters to be consider while designing a MR Damper. From the experimental results it was witnessed that the magnetorheological assisted fixture reduces the vibration during machining significantly and improves the surface roughness and machining performance.

Effect of Cavity Size on Performance of Particle Damper

Abstract: Particle damping is a damping technique that has found wide applications in engineering systems. It is a form of damping where the energy dissipation is achieved through the motion of small particles within a cavity. This technique has several unique features that make it an attractive option for many engineering applications. Cantilever beam with FFT analyzer is used to find the response parameters. The readings are taken with varying cavity dimensions, size of ball, packing ratio and ball material. The readings in the form of acceleration are noted by varying one experimental parameter. From the experimentation it is found that 24 mm diameter and height 37 mm cavity with 50% Packing ratio is effective for the applied experimental set-up.

A stability-based energy-dissipation design method of viscoelastic dampers

Viscoelastic damper (VED) is one of the most effective velocity dampers, which can provide equivalent stiffness and damping for structures. The stability of the damper is an important factor affecting the control performance of dampers. However, most research works on the stability are focused on metal dampers, few research works on the stability of velocity dampers have been carried out. To solve the stability problem of VED, an energy-dissipation design method considering the stability of VED is proposed in this paper. Through parametric analysis, relationships between height-thickness ratios, loading frequency and stability-bearing capacity of VEDs are established. Then, the concepts of stability coefficient and frequency coefficient of VED are added into the mechanical model of VED. Subsequently, pseudo-dynamic tests and variable frequency loading tests are carried out for two groups of full-scale VEDs to verify the reliability of the stability coefficient and frequency coefficient. Here, a stability-based energy-dissipation design method of VEDs is proposed. Based on an actual project, nonlinear time-history analyses are carried out for the original structure and the controlled structure ignoring/considering the stability respectively. Results indicate that control effects considering stability are lower than control effects ignoring stability. In other words, it is shown that ignoring stability of VED will result in not meeting energy-dissipation expectations, which may bring potential safety hazards to the structure. Finally, to improve its stability, a new VED with improved out-of-plane stiffness is proposed. It can be concluded that it is necessary to take the VED stability into account in the design and performance evaluation of VE structures using the proposed method.

A Vibration Control Method Using MRASSA for 1/4 Semi-Active Suspension Systems

The multi-subpopulation refracted adaptive salp swarm algorithm (MRASSA) was proposed for vibration control in 1/4 semi-active suspension systems. The MRASSA algorithm was applied to optimize suspension damping performance by addressing the local optimal and slow convergence speed challenge of the standard salp swarm algorithm for two-degrees-of-freedom 1/4 semi-active suspension systems. The developed MRASSA contains three key improvements: (1) partitioning multi-subpopulation; (2) applying refracted opposition-based learning; (3) adopting adaptive factors. In order to verify the performance of the MRASSA approach, a 1/4 suspension Simulink model was developed for simulation experiments. To further validate the results, a physical platform was built to test the applicability of the simulation model. The optimized suspension performance of MRASSA was also compared with three optimized models, namely, standard SSA, Single-Objective Firefly (SOFA) and Whale-optimized Fuzzy-fractional Order (WOAFFO). The experimental results showed that MRASSA outperformed the other models, achieving better suspension performance in complex environments such as a random road with a speed of 60 km/h. Compared to passive suspension, MRASSA led to a 41.15% reduction in sprung mass acceleration and a 15–25% reduction compared to other models. Additionally, MRASSA had a maximum 20% reduction in suspension dynamic deflection and dynamic load. MRASSA also demonstrated a faster convergence speed, finding the optimal solution faster than the other algorithms. These results indicate that MRASSA is superior to other models and has potential as a valuable tool for suspension performance optimization.

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.

Green self -vulcanizable rubbers with recyclable, self-healable capabilities and excellent damping performance

The vulcanization of rubbers is a prerequisite for their practicality. Currently adopted vulcanization methods for rubbers are suffering from some persistent problems, such as the utilization of harmful vulcanizing additives, the generating of volatile organic compounds, and the difficulties in the recycling of end-of-life rubbers. To meet the need of sustainable development, a facile and green self-vulcanization method is used to prepare self-healable and recyclable damping rubbers. Hydrogenated carboxylated nitrile rubber (HXNBR) and epoxidized nature rubber (ENR) can efficiently self-vulcanize by forming β-hydroxyl ester crosslinks without adding vulcanizing agent. Zinc oxide and epoxidized soybean oil are added as additives to adjust the self-vulcanization of HXNBR/ENR compound. Phenolic resin can make HXNBR/ENR composite to become a good damping material, and significantly improve the self-healing capacity of the composite. Additionally, the end-of-life self-vulcanized HXNBR/ENR composites can be recycled and reprocessed by selectively cleaving the ester bonds in the crosslinked structure, resulting in a very high recovery of mechanical performance of the recycled composites, which proves that this is a facile and efficient rubber recycling method.

Interacting Multiple Model Strategy Based Adaptive Wide-Area Damping Controller Design for Wind Farm Embedded Power System

The intermittent nature of Wind Turbine Systems (WTSs) can severely affect the Low-Frequency Oscillations (LFOs) in the power system. Hence, a Wide-Area Damping Controller (WADC) is designed in this paper to provide adequate damping to critical LFO modes. This WADC utilizes a modal-based prescribed degree approach, ensuring the specified shift of concerned modes from their existing position. However, the design of WADC at a fixed operating point and time delay in feedback signals does not provide robust performance as these uncertainties may vary for different time intervals. Specifically, time-varying delays should be tackled appropriately, or the system's damping performance will be severely hampered. Keeping this in view, an Interacting Multiple Model (IMM) infrastructure is employed to provide robust damping performance for such uncertainties. The IMM strategy utilizes the deviation of output error between actual and probable plants, through which weights are assigned to corresponding probable WADCs via the Bayesian framework. The simulations are performed on the nonlinear 4-machine, 11-bus system and the complex 16-machine, 68-bus system using MATLAB/Simulink platform. The results demonstrate that the proposed IMM-based WADC furnishes adequate damping to critical LFO modes for operating point and time delay uncertainties.

Dynamic Energy Dissipation Performance of Nonlinear Large-Deformation Viscoelastic Joint Damper under Strong Dynamic Load

Large-displacement corner deformation often occurs at the joints of towering structures and long-span space structures subjected to strong earthquake. In order to improve the energy dissipation capacity of structural joints, the Nitrile Butadiene Rubber/High Abrasion Furnace Black (NBR/HAF) high damping composite was fabricated by formulation optimization in this paper, where a nonlinear large-deformation viscoelastic joint damper was proposed. The damper consists of five layers of restrained steel plates and four layers of shear energy dissipating material, which can reach 60[Formula: see text]mm shear displacement. In this paper, dynamic mechanical performance tests and static mechanical tests were firstly conducted on the core energy dissipating media of the damper. The loss factor of NBR/HAF composite reached a peak of 1.51 at about 8.2°C, while its wide damping temperature range was 27°C. Second, the accuracy of the simulation method was verified by comparing the simulated and experimental hysteresis curves. Then, the refined numerical simulation of this damper was carried out using ABAQUS finite element software with the high damping material as its core energy dissipating media. Finally, the magnitude and type of energy dissipation of each part of the viscoelastic joint damper under different loads were investigated. It was found that the large-deformation viscoelastic joint damper based on the composite had good damping capacity. Its dynamic characteristics were affected by the displacement amplitude and excitation frequency, which exhibited hardening nonlinear characteristics. As the frequency and load amplitude increased, the peak displacement in the loading direction gradually decreased, whereas the total energy input to the damper and the energy dissipated by the viscoelastic material increased monotonically. The input energy was only dissipated by the viscoelastic material, and no plastic loss occurred in the steel plate during the entire loading stage. Under high frequency and large loads, the damper can also have good energy dissipation characteristics. Because of the negative strain energy caused by plastic dilatancy, the energy dissipated by the material was gradually greater than the input energy with the load increasing.

Effect of Ball Size on Performance of Particle Damper

Abstract: The study of particle damping involves the understanding of the various forces and mechanisms that cause energy to be lost from vibrating systems, leading to the reduction of their amplitudes over time. The cantilever beam is used for experimentation. FFT analyzer is used to find the response parameters. The readings are taken with varying cavity dimensions, size of ball, packing ratio and ball material. The response parameters in the form of acceleration are noted by varying one experimental parameter. From the experimentation it is found that 5 mm ball with sand material is effective for the applied experimental set-up.

Experimental investigation of structural behavior of 316L stainless steel and carbon steel slit dampers

To expand the range of applications for stainless steel in building structures, previous studies have tested the seismic resistance of structural elements and members using a variety of types of stainless steel. Steel slit dampers have been designed and installed for seismic retrofits of building structures. In this study, hysteresis behaviors of austenitic stainless steel (STS316L) and carbon steel (SS275) slit dampers were investigated and compared to demonstrate the excellent seismic performance of stainless-steel slit dampers. Monotonic and cyclic material tests for STS316L and carbon steel were conducted. STS316L had the best seismic performance, with much greater ductility, strength enhancement and cyclic hardening effect than SS275. STS316L with increased nickel (Ni) and reduced chromium (Cr) contents transformed to exhibit twinning induced plasticity (TWIP) steel after yielding under cyclic loading and thus possesses a more stable austenitic microstructure than SS275 and STS304. Loading experiments with STS316L and SS275 slit dampers were performed according to six loading protocols. The fracture shapes, stiffness, ductility, yield strength and energy dissipation capacity also were compared. STS316L dampers provided greater secondary stiffness, ultimate strength, number of cycles and energy dissipation capacity than SS275 dampers. The ultimate strength and normalized energy dissipation capacity of the STS316L specimens were on average 1.53 times and 4.84 times larger, respectively, than those of the SS275 specimens thanks to excellent ductility and strong cyclic hardening effects at the material level. This study proved that the performance of austenitic stainless steel STS316L as a seismic material and slit damper is superior to those of mild carbon steel SS275 and austenitic stainless steel STS304.

Energy research of three-adjacent structures connected by Kelvin-type dampers based on power flow

The control effect of a three-adjacent structural system connected by Kelvin-type dampers and its energy transfer and distribution under uncertain and deterministic excitations are investigated in this study. A simplified model of multi-degree-of-freedom mechanics is used for establishing structural equations; the power flow equations of this structural system are derived based on the power flow theory. The influence law of a structural parameter changes on the input power flow when the damper that is not connected is investigated; the damper parameters are optimized using the NSGA-II (Non-dominated Sorting Genetic Algorithm-Ⅱ) algorithm after connecting the dampers, and the damping control effect is evaluated. Next, the variation law of the input power flow of the structure and damper is analyzed with the structure and damper parameters as study variables. These results indicate that an increase in structural stiffness has a positive excitation effect on the seismic performance improvement of the structure; the influence of the structural damping ratio on the input power flow is sufficiently small. The influence of change in damper parameters on the input power flow is closely related to the structural parameter setting. The three-adjacent damping structure system connected to optimal parameter dampers exhibits a good damping performance when the structural parameters are determined.

Analysis of DFIG Interval Oscillation Based on Second-Order Sliding Film Damping Control

This paper takes advantage of the high control flexibility and fast response time of the interfacing power electronic converter for doubly fed wind turbine grid-connected systems to address inter-area oscillations caused by inadequate system damping in power systems. A reactive-power-coordinated damping controller for a doubly fed induction generator (DFIG) is proposed, and it makes use of second-order sliding-mode technology. The suggested controller improves damping performance by controlling the reactive power. It provides benefits such as a quicker damping rate and resilience to modeling errors and parameter changes. The simulation results indicate the system’s improved performance in inter-area oscillation damping and the robustness of the suggested control technique over a broad range of functional areas.

Computational Comparison of Performance of Different Steel Plate Shear Yielding Dampers

The computational modeling of hysteretic dampers is a powerful tool for design, allowing us to predict and optimize damper performance. In this research, a numerical model, based on Chaboche’s nonlinear kinematic hardening constitutive law, was implemented. The parameters of this law were identified and validated by inverse analysis, based on the macro-hysteretic response of the hexagonal honeycomb steel damper. The validated model was applied to simulate the cyclic loading behavior of five proposed steel plate shear yielding dampers (SPSYDs), which were then used to compare the hysteretic performance in terms of effective stiffness, effective damping, and energy dissipation capacity. The parametric analysis of design variables performed on the SPSYDs demonstrated that the plate depth does not modify the effective damping, and the thickness is the most significant factor affecting the maximum displacement, dissipation energy and endurance cycles. The comparison of the performance of the dampers allowed us to establish design guidelines for the SPSYDs, which allow the device to be adjusted with the requirements of the building in which it is installed.

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.

The effects of structure-soil-structure interaction on seismic response of high-rise buildings equipped with optimized tuned mass damper

Nowadays, various vibration control tools and methods are used to improve the behavior of structures. Tuned Mass Damper (TMD) is one of the simplest and most used passive control tools, which consists of a combination of spring, mass, and a damping mechanism. However, some factors, such as the type of soil beneath the structure and the existence of another structure, can affect the damper's performance. This study investigates the effects of Structure-Soil-Structure Interaction (SSSI) on the seismic response of two 20-story steel moment frames equipped with TMD. Assuming an elastic behavior for the soil and plane strain problem, the reduced stiffness matrix of the foundation-soil-foundation system is obtained using static analysis of the 2D finite element method in Abaqus. Then, it is applied to 2D linear models of structures using a combination of springs and a newly developed element in OpenSEES. Furthermore, particle swarm optimization algorithm is used to optimize the design parameters of TMD. The seismic responses are obtained under ten far-field seismic records from the time history analysis. The results reveal that considering SSSI can significantly increase the responses of both structures. Nevertheless, exploiting TMD with optimized parameters in the 20-story structures reduces the seismic responses.

Experimental study on the dynamic performance of a winding rope fluid viscous damper

This study proposed a winding rope fluid viscous damper (WRFVD) using the winding ropes to amplify the damping force of a fluid viscous damper. To investigate the dynamic performance of the WRFVD, four different prototypes were fabricated and tested under a series of sinusoidal loading protocols. Experimental results demonstrated that the WRFVD is a velocity-dependent damping device with significant and stable energy dissipation capacity. The winding rope amplification mechanism can effectively amplify the damping force of the fluid viscous damper by 3 to 6 times, and amplify the energy dissipation of the fluid viscous damper by 3.5 to 6.9 times. After 30 cycles of fatigue loading, the maximum damping force and the energy dissipation capacity of the WRFVD almost not decayed. The damping force of the WRFVD had a linear relationship with the damping force of fluid viscous damper with the coefficient of β, and β was only related to the construction of the WRFVD itself. The theoretical model of damping force based on the Maxwell-β nonlinear model could reflect the mechanical properties of the WRFVD well, and the theoretical and experimental hysteresis curves are in good agreement.

Experimental and theoretical research on a shear-bending-metallic-damper with a double-phased yield mechanism

Aiming at improving the performance and practicability of metallic dampers, this paper proposes a novel shear-bending metallic damper with a double-phased yield mechanism (SBD-DY) by setting bending and shear plates with different yield strengths in parallel. The double-phased yield mechanism enables the damper to provide proper energy dissipation ability and stiffness for the primary structures during various earthquakes. Design methods of SBD-DY, including the elastic stiffness, the yield strength, the yield displacement, the force-displacement relationship and the membrane effect, are proposed. Ten SBD-DY specimens are tested under monotonic and cyclic loading to verify the workability of the bending and shear plates. The test results reveal that the SBD-DY specimens demonstrate satisfactory plastic development with full hysteresis curves, favorable energy dissipation ability and good ductility. Two types of failure modes, namely the weld failure of bending plates and fracture of strips, are summarized. Test specimens with fracture of strips exhibit better residual load capacity and energy dissipation ability than specimens with weld failure of bending plates. The effects of parameters including width of bending plates (B), height of bending plates (H) and width of the strips (S) are compared and analyzed. The theoretical results agree well with the experimental results, clearly revealing the double-phased mechanism of SBD-DY. Finally, potential improvements are also proposed to avoid premature weld failure of SBD-DY.

Experimental study on frictional behavior of different structural materials

Friction dampers were widely applied to the beam-column connections to dissipate earthquake energy. The damage of buildings under earthquake could then be reduced obviously. To ensure the good performance of the friction dampers, the appropriate selection of the materials for the friction pads was important. This paper investigated the coefficient of friction of different materials under cyclic loading. Four types of materials which included steel, galvanized steel, brass, and aluminum were chosen. The studied variables were the surface cleaning process, the bolt pretension, and the loading protocols. The test results showed that the shot blasting process significantly enhanced the coefficient of friction and the energy dissipation ability. Friction dampers with friction pads made of these four materials offered high initial stiffness. They could provide the needed stiffness for the structures. The coefficient of friction was largely affected by the bolt pretension and the loading protocols. Except for the friction damper with friction pads made of aluminum, the other three friction dampers exhibited satisfactory energy dissipation ability without obvious strength degradation. Mathematical models were proposed to predict the variation of the coefficient of friction for different materials. Good agreement was found between the prediction and the test data.