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This paper reports an experimental and analytical investigation on a novel self-centering damper. The damper is characterized by a multistage energy-dissipation mechanism, which is desirable for multiperformance-based seismic designs. The conceptual design, working mechanism, assembling process and hysteretic performance of the proposed damper are presented. The fundamental mechanical behavior of each component of the damper was examined experimentally. Then a series of cyclic tests of damper specimens was conducted, focusing on the influence of the preload of the shape-memory alloy (SMA) bolts, the SMA bolt type, and the sloping angle of the wedge-shaped friction plates on the damper performance. An analytical model is proposed for quantification of the hysteretic behavior of the damper. The test results showed that the damper specimens exhibited the expected multistage energy-dissipation characteristics and stable flag-shaped hysteretic curves with full self-centering behavior. A good energy dissipation capacity with an equivalent viscous damping (EVD) of about 20% was observed, which basically was consistent over the entire loading stages. The overall behavior of the damper was related closely to the aforementioned test parameters, indicating that the damper performance can be adjusted flexibly according to various seismic design requirements. The analytical predictions and the test results of the damper were in good agreement, indicating that the developed analytical model can be used confidently by engineers for the design of the developed damper. [ABSTRACT FROM AUTHOR]

Researchers in the field of vibration control have shown increasing interest in magneto-rheological dampers (MRDs) in recent years. Conventional flow-mode MRDs typically employ a gas chamber as an accumulator to accommodate volume changes and promote fluid communication. However, this approach introduces manufacturing complexities and raises production costs. To overcome these challenges, we propose a novel configuration for flow-mode MRDs that replaces the accumulator with a structural constraint. This modification leads to a more compact and cost-effective MRD solution suitable for engineering applications. This paper presents an introduction, followed by the configuration and design of the novel MRD for a case study involving a vehicle suspension system. To enhance output performance, we optimize the significant geometry of the damper using the finite element method (FEM), taking into account the damping force, off-state force, and inductive time constant of the damper. Based on the optimal simulation results, we provide a detailed design of the optimized flow-mode MRD without an accumulator for prototype fabrication. To assess the practical performance of the proposed MRD prototype, we conducted experiments on a test rig and engaged in comprehensive discussions based on the obtained results. [ABSTRACT FROM AUTHOR]

This article presents research into the feasibility of applying a nonlinear damper of a new conceptual structure. The key component of the damper is a circular membrane with slits that can move in a cylinder filled with viscous fluid. When an external load is applied to the damper, the membrane deforms, opening the slits. The flow of viscous fluid through the slits generates a damping force. The phenomenological model of the damper is based on the notion that the slit membrane moves according to the fundamental axisymmetric vibration mode of a circular membrane. The slit membrane blocks the entire radius of the pipe in the state of equilibrium when all slits are closed. As the membrane moves, the opening area of the slits varies depending on its deformation. This gives a nonlinear damping characteristic. The damping constant depends on the input displacement and velocity, which is the reason for the nonlinearity of the damping characteristic. From the phenomenological model, the nonlinear characteristic of the drag force is obtained. The performance of the damper is simulated using a mass–spring–damper system. Two cases of harmonic excitation and impulse excitation are analyzed. The results show that, using the slit membrane damper, the suppression of dynamic loads is more effective compared to a conventional linear damper. [ABSTRACT FROM AUTHOR]

Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Magnetorheological elastomers (MREs) are smart materials. Their rheological properties can be controlled by applying an external magnetic field. MRE is a solid rubbery material that can change its modulus through the application of a magnetic field. This article presents the research on the simulation, manufacturing, and testing of vibration insulators. The first step in MRE vibration isolator design. A sufficient magnetic field for the stiffness change is considered in the material selection of the vibration isolator. The effectiveness of electromagnetic circuits in generating magnetic fields to minimize vibration is demonstrated using Finite Element Method Magnetics software. A vibration isolator test rig is installed as a second step. Lastly, different effects of current input on MRE isolators have been examined. The higher current input is more effective in eliminating vibration using the MRE isolation system.

The use of machines and technology in the industrial sector has led to noise pollution, which requires attention. The practice of noise control through soundproofing is closely linked to the use of various acoustic materials, whether they are synthetic or natural fibers. Natural materials are preferred for biocomposite reinforcement due to the design flexibility, environmental friendliness, sustainability, and ease of availability. Therefore, this research aimed to analyze the variation of grinting grass (Cynodon Dactylon) composite material as damper with safe working distance from noise exposure. This experimental research was conducted using industrial grinding machine and damper from grinting grass as the object and composite material. The instruments used for measurement included an Impedance tube (sound absorption coefficient), a Sound Level Meter (noise intensity), and a Surfer 13 noise mapping application. The data obtained were analyzed using the Wilcoxon test to determine the differences before and after the intervention. The results showed that the most effective composite had a 60:40 ratio with a sound absorption coefficient of 0.30. Before using damper, the highest noise intensity recorded was 106 dBA, which was reduced to 83 dBA. Safe working distance from exposure before damper was 6.1 meters, which decreased to 1 meter after the intervention. In conclusion, there was a significant difference in noise intensity (p-value= 0.000) and safe working distance from exposure (p-value= 0.001) before and after the use of grinting grass as damper

Abstract To improve the energy dissipation and self-resetting ability of bridge structures under strong earthquakes, a new buckling-restrained SMA bar-based friction damper (SFD) is proposed. The damper is composed of buckling-restrained super-elastic SMA bars, friction pads, and a steel frame. The buckling-restrained SMA bars provide self-reset capability, while the friction pads provide additional energy dissipation capacity. Firstly, the configuration, working mechanism, and restoring force model of the SMA bar-based friction damper are introduced. Secondly, a specimen of the damper is made, and the pseudo-static test is carried out. Finally, the experimental results are analyzed based on the Abaqus finite element model. The results indicate that the damper has better self-resetting ability and energy dissipation capacity.

To improve the energy dissipation and self-resetting ability of bridge structures under strong earthquakes, a new buckling-restrained SMA bar-based friction damper (SFD) is proposed. The damper is composed of buckling-restrained super-elastic SMA bars, friction pads, and a steel frame. The buckling-restrained SMA bars provide self-reset capability, while the friction pads provide additional energy dissipation capacity. Firstly, the configuration, working mechanism, and restoring force model of the SMA bar-based friction damper are introduced. Secondly, a specimen of the damper is made, and the pseudo-static test is carried out. Finally, the experimental results are analyzed based on the Abaqus finite element model. The results indicate that the damper has better self-resetting ability and energy dissipation capacity. [ABSTRACT FROM AUTHOR]

Based on the arctangent function, this work proposes a parametric model to predict the mechanical behavior of a shear thickening fluid damper. The parameters of this model are a function of the maximum operating velocity of the damper. The validity and accuracy of the model's damping force and displacement relationship under different sinusoidal loads and various seismic wave excitations are verified based on experimental data. On this basis, compared to a viscous damper, the finite element models of a stay-cable and shear thickening fluid damper system are established to evaluate the vibration reduction performance and mechanical advantages of the shear thickening fluid damper. The research shows that a shear thickening fluid damper can significantly reduce the amplitude of the stay-cable's primary resonance and main parametric vibration, with displacement reduction rates of 72.5 and 81.9%, respectively. Importantly, compared to viscous dampers, under the premise that both have the same damping force, the vibration reduction effect of shear thickening fluid dampers is more significant, 1.3 times and 1.15 times that of viscous dampers, and the stroke is only 55.2 and 59.7% of that of viscous dampers. These data indicate that shear thickening fluid dampers can provide a more significant damping force for stay-cable in limited space. [ABSTRACT FROM AUTHOR]

Iron-based shape memory alloy (Fe-SMA) is an emerging class of material having a great potential for civil engineering, especially seismic engineering applications. However, the behavior of Fe-SMA strongly depends on temperature-sensitive martensitic transformation, and thus the influence of temperature on the behavior of Fe-SMA should receive particular attention. The current study experimentally investigates how temperature variation affects the mechanical properties, including monotonic tensile strength, low cycle fatigue (LCF), and impact toughness, of Fe-SMA (Fe-17Mn-5Si-10Cr-5Ni in wt%), with a particular focus on its low-temperature behavior. Specifically, the considered temperatures used for conducting monotonic tensile and LCF tests were −40°C , −10°C , and 20°C, whereas the range of temperature for impact toughness tests was from −100°C to 20°C. Additional tests were performed on S30408 stainless steel and conventional Q355 structural steel for comparison purposes. The experimental results suggest that low temperature leads to increased strength and reduced ductility of Fe-SMA. The impact toughness of Fe-SMA is comparable with that of S30408 steel, exhibiting ductile fracture characteristic observed even at −100°C. Fe-SMA outperforms conventional steels with an evidently greater LCF life given the considered temperature variation; although, its LCF life decreases at lower temperatures due to the inhibited reversible martensite transformation. This study also provides a set of practical parameters that facilitate constitutive modeling and strain-based fatigue life prediction of Fe-SMA under various temperatures. [ABSTRACT FROM AUTHOR]

Copyright of Journal of South China University of Technology (Natural Science Edition) is the property of South China University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To reduce the cost of small wind turbines, a prototype of a butterfly wind turbine (6.92 m in diameter), a small vertical-axis type, was developed with many parts made of extruded aluminum suitable for mass production. An overspeed control system with movable arms that operated using centrifugal and aerodynamic forces was installed for further cost reduction. Introducing this mechanism eliminates the need for large active brakes and expands the operating wind speed range of the wind turbine. However, although the mechanism involving the use of only bearings is simple, the violent movement of the movable arms can be a challenge. To address this in the present study, dampers were introduced on the movable arm rotation axes to improve the movement of the movable arms. To predict the behavior of a movable arm and the performance of the wind turbine with the mechanism, a simulation method was developed based on the blade element momentum theory and the equation of motion of the movable arm system. A comparison of experiments and predictions with and without dampers demonstrated qualitative agreement. In the case with dampers, measurements confirmed the predicted increase in the rotor rotational speed when the shorter ailerons installed perpendicularly to the movable arms were used to achieve the inclination. Field experiments of the generated power at a wind speed of 6 m/s (10 min average) showed relative performance improvements of 11.4% by installing dampers, 91.3% by shortening the aileron length, and 57.6% by changing the control target data. The movable arm system with dampers is expected to be a useful device for vertical-axis wind turbines that are difficult to control. [ABSTRACT FROM AUTHOR]

Research on noise pollution reduction has focused on utilizing damping coatings and polymer nanocomposites to enhance sound absorption. Nanosilica/poly(styrene-acrylate) nanocomposites as a water-based coating were prepared through in-situ emulsion polymerization and direct mixing methods at varying concentrations of 1, 2, and 3 wt% of nanosilica. Fourier transform infrared (FTIR) spectroscopy revealed that the inclusion of surfactant-containing micelles and a more extended synthesis period in the in-situ synthesis technique enhanced the interaction between silica nanoparticles and polymer chains. Dynamic light scattering (DLS) analysis showed a unimodal distribution and an acceptable range of polydispersity index (PDI) for neat and nanocomposite latexes. The addition of silica nanoparticles enhanced the stability of latex particles, especially evident in the direct mixing method. The field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) images confirmed the better dispersion of nanoparticles within the polymer matrix in the in-situ method. The addition of nanosilica resulted in a significant increase in pseudoplastic behavior and viscosity, notably in the in-situ synthesis. In both the in-situ synthesis and direct mixing techniques, the addition of 1 wt% of nanosilica resulted in an increase in the damping factor of nanocomposite films to about 2. However, when the nanosilica content was further increased to 3 wt%, the damping factor decreased. Acoustic tests demonstrated improved sound absorption with silica nanoparticles, yielding noise reduction coefficient (NRC) values of 0.49 and 0.46 for in-situ synthesis and direct mixing. The direct mixing method notably enhanced tensile properties at all nanoparticle content levels. Dried nanocomposite films exhibited superior UV-blocking capabilities compared to neat polymer films.

Copyright of Journal of Southeast University / Dongnan Daxue Xuebao is the property of Journal of Southeast University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We present the results of studying the influence of the geometric shape of the damper on its effectiveness and the overall efficiency of the emission–reception system. One of possible shapes for the damper is considered where it is a truncated cone with the generatrix tilted relative to the piezoelectric plate plane. A criterion for evaluating the efficiency of the damper operation is proposed. The study includes the results of computational-theoretical (using the finite element method) and experimental research on the influence of the tilt angle of the damper generatrix on the signal reflected from its rear part. The generatrix tilt angle at which the minimum of noise signal is achieved is determined. A study of the emission–reception system under load on the aquatic environment is carried out. A satisfactory agreement between the theoretical and experimental results is noted. [ABSTRACT FROM AUTHOR]

Copyright of Journal of China University of Petroleum is the property of China University of Petroleum and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Magnetorheological fluids (MRF) are intelligent materials that can vary their yield stress in response to an applied magnetic field. This characteristic, combined with active and multifunctional control, allows the development of actuators with fast response time, low energy consumption, long service life, and reduced dimensions and weights. Various studies have been conducted to improve MR dampers in prosthetic applications, including knees, ankle-foot, hands, and sockets. Here, we present a critical review of the progress of MRFs in the prosthetic field. In addition, research in prostheses' design, optimization, and control of magnetorheological actuators is investigated, along with MRF modeling, mode of operation, type of MR actuator, classification, and working principle of MRF-based devices. Although MRFs are considered promising materials for designing novel prosthetic devices, this review shows that applications have been predominantly focused on lower limb prostheses. We conclude by discussing possible future applications and challenges that must be faced to enable and improve commercial applications based on MRF technology. [ABSTRACT FROM AUTHOR]

Offshore wind turbines (OWTs) are exposed to cyclic loads resulting from wind, waves, and rotor rotation. These loads can induce resonance, thereby significantly increasing the amplitude of the structure and accelerating the accumulation of fatigue damage. Particularly, wave loads can induce the first mode of large turbines. While many studies have been conducted to suppress OWT vibrations due to external loads, research on variable natural frequency damper (VNFD), which control vibrations through changes in the natural frequency by adjusting the inner water level of the structure, is still in its infancy. Herein, the performance of a VNFD in controlling the vibration of monopile-type OWTs is analyzed by focusing on cyclic environmental loads. To analyze the amplitude minimization achieved using a VNFD, wave loads with the same period as that of the structure's natural frequency were generated, and the structural response resulting from changes in the inner water level were analyzed. As a result, the peak displacement at the top of the tower decreased by 5.8% and 34% at the water depths of 20 m and 50 m, respectively. In terms of the peak intensity determined through Fast Fourier Transform of the displacement response, reductions of 33% and 65% were confirmed at the depths of 20 m and 50 m, respectively. [ABSTRACT FROM AUTHOR]

This study presents a finite element model for a hybrid self-centering damper considering the rate and temperature effects and explores the effects of different design parameters on the damper response. The damper, called as superelastic friction damper (SFD), consists of superelastic shape memory alloy (SMA) cables and a frictional energy dissipation mechanism. The experimental response of the SMA cables, frictional unit and overall damper at different loading frequencies and temperature are used to develop numerical model of the damper. Once a validated numerical model is obtained, parametric studies are carried out to evaluate force-displacement response of the damper when the design parameters are altered. The effects of damper design parameters on the equivalent stiffness, dissipated energy, equivalent viscous damping and self-centering capabilities of the damper are analyzed. Based on the findings, the recommendations for the design of the damper are presented. [ABSTRACT FROM AUTHOR]

Aiming at the shortcomings of traditional contact cable force monitoring technology in accuracy, efficiency, and applicability, an assessment method based on microwave radar measurements is proposed to measure a sloping cable with a damper for lengths greater than 200 m in this study. A formula for calculating the cable-stayed force with a damper is derived, and an intelligent cable force monitoring platform is developed based on cloud technology. Based on the Chongqing Nanjimen Railway Bridge, a real bridge test was carried out. It was indicated that the microwave radar method could be used to freely adjust the measurement angle and possessed high applicability and penetration. It significantly improved the measurement accuracy and efficiency of cables with a damper for lengths greater than 200 m. It has good application value for the solution of the problems of complicated operation and high costs in the monitoring of cables with a damper. The formula for calculating the cable force with a damper was proven to be reliable and accurate when compared to the results of direct calculation and the equivalent cable length method. It was able to significantly reduce the calculation error of the cable force caused by the influence of the damper. Additionally, the intelligent cable force monitoring platform was utilized to enhance the level of digitization, providing technical support for the scientific management and maintenance of bridges. [ABSTRACT FROM AUTHOR]

Earthquakes occur without warning and cause considerable shock to structures by shaking the ground. If deformation or damage beyond the permissible range occurs in a structure owing to an earthquake, serious problems arise in terms of usability, repair, and reinforcement. Therefore, numerous seismic reinforcement devices have been developed to prevent structural damage caused by earthquakes. However, the existing seismic reinforcement devices are problematic because they need to be replaced after an earthquake owing to deformation. Therefore, in this study, we developed a pretension damper, a seismic reinforcement device that exhibits excellent recentering, load resistance, and energy dissipation capacity performances by applying superelastic shape memory alloy wire with pretension and friction bolts, and analyzed the behavior characteristics. For this purpose, the design parameters set as the diameter and material of the wire, pretension, and friction bolts. Finite element analysis was performed using the ABAQUS program for a total of 24 dampers according to design parameters, and maximum load performance, energy dissipation capacity, residual displacement was analyzed. The results confirmed that the recentering and load resistance performance are improved when pretension is applied, and the energy dissipation performance is improved when friction bolts are installed. Applying the superelastic shape memory alloy instead of Gr. 50 steel enhances the damper performance in terms of the maximum force, energy dissipation capacity, and residual displacement. In particular, when pretension is applied to Gr.50 steel wire, performance deteriorates, so pretension is not recommended in this case. In particular, the application of pretension to Gr.50 steel wire is not recommended due to reduced performance. The best performance was SPF20 damper, which showed a maximum load of 1153.7 kN, residual displacement of 0 mm, and energy dissipation capacity of 309855.19 kN·mm.

The implementation of the programme for modernisation of Russian oil refineries, launched in 2011, has already significantly increased the depth of oil refining and the quality of petroleum products. It has had a positive effect on reducing the country’s dependence on crude oil exports and has made it possible to obtain a significant positive environmental effect. However, at the same time, there has been a decrease in marginality. At the present stage, the main problems of the Russian oil refining, which affect, among other things, the implementation of modernisation projects, are associated with a ban on the supply of equipment and software for oil refining, the imposition of an embargo and a price ceiling for oil products. The article analyses the results of the implementation of the modernisation programme in terms of the impact on economic and environmental performance of oil refineries and the impact of sanction restrictions on the further modernisation of enterprises. It also considers possible ways to solve problems through the development and implementation of modern production technologies in combination with digital solutions.

In the present paper, the impacts of viscous dampers on controlling the vibrations imposed on seismic vibrations are evaluated using descriptive methods. To this end, the library method and other research related to viscous dampers and their impacts on controlling external excitation such as earthquakes have been used. ETABS software was used for modelling the structures. Also, nonlinear dynamic analysis was used for seismic analysis of the structures. Based on the findings, using viscous dampers are effective to improve seismic parameters of structure and to decrease displacement, speed, base shear, and velocity. On the other hand, viscous fluid dampers can strengthen the structure and its performance during severe earthquakes and can be applied in newly constructed structures. The impact of a passive viscous damper on reducing the seismic response of the structures is found significant at the confidence level of 90%. Reduction of energy of structure hysteresis because of the nonlinear behaviour of members using dampers is proved to be significant at the confidence level of 80%. The results reveal that the lateral resistance of an EBF with a short joint can be 4/5 to 9 times more than the lateral resistance of an MRF, that the behaviour coefficient of fifteen-story EBF considered 6/5-7/75, concluded that the length of the bray does not have an impact on the behaviour coefficient of these frames. [ABSTRACT FROM AUTHOR]

Summary: Although the concentrically braced frames (CBFs) systems have high lateral elastic stiffness and strength, they reflect a low seismic energy absorption capacity mainly due to their diagonal buckling under compressive loading. To overcome this problem, researchers have proposed metallic shear damper as the most popular due to its satisfactory performance and affordable cost. In this paper, an innovative metallic damper with a flexural mechanism is proposed to improve the behavior of CBF systems. It provides ease of fabrication and replacement after damage, competitive cost, and improved resistance to buckling of the CBF member. The performance of the damper was evaluated experimentally and numerically. Subsequently, two types of dampers, (a) made of rectangular flexural plates (RFP) and (b) made of I‐shaped flexural plates (IFP), were designed and evaluated. Experimental as well as numerical results indicated that both dampers provide stable and symmetrical hysteresis curves with a high energy absorption capacity. Results indicated that the IFP damper has greater stiffness (1.94–2.3 times) and ultimate strength (1.76 times) but a lower overstrength (66% less) and ductility (47% less) than the RFP damper. Moreover, design expressions were presented for the proposed damper and showed a good agreement with finite element results. [ABSTRACT FROM AUTHOR]

The results of a study on the geometric shape of the damper on the efficiency of the ultrasonic piezoelectric transducer are presented. In particular, a damper in the form of a truncated cone is considered, the generatrix of which has an inclination angle α relative to the diameter of the piezoceramic plate. The shape of the damper in the form of a truncated cone is chosen based on the a priori assumption that this helps to increase the path of the wave in the damper material due to numerous reflections in it. A criterion for the efficiency of damper operation is proposed. The optimal (from the point of view of the damper efficiency) value of the angle α was determined theoretically and experimentally. The technology of its production is described. Satisfactory agreement between the results of theoretical and experimental studies was noted. [ABSTRACT FROM AUTHOR]

In this study, the vehicle seat suspension system installed with a semi-active magnetorheological (MR) damper is excited by the power spectral density (PSD) and its vibration control performance is evaluated using finite element analysis (FEA). The control system receives the velocity of the sprung and unsprung mass from the seat mounting locations and calculates the desired controllable damping forces available from MR damper. The effectiveness of the control systems is demonstrated by adopting ride quality evaluation method. To predict a better ride comfort and ride quality, co-simulation methodology is utilized considering the dynamic behavior of the real-world seat system. In this case, the multi-body dynamics and control system are coupled by solving the mechanical equations and the control logic. Then, the computed damping force is exchanged between the dynamics and controller in an iterative manner by passing state variables. The simulation results achieved from co-simulation methodology associated with the controller are analyzed by comparing with ISO 2631-1. The co-simulation results studied using vibration dose value (VDV), crest factor (CF) and seat effective amplitude transmissibility (SEAT) in terms of percentage improvement were found to be 44.33%, 26.66% and 17.65% respectively which were better than that for the passive suspension for a random rough road profile. Modified skyhook controller delivers superior performance for vibration suppression of the vehicle seat suspension as compared to other control policies. The application of co-simulation methodology can reduce time and cost for the development of a semi-active seat suspension system. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Computational Mechanics / Jisuan Lixue Xuebao is the property of Chinese Journal of Computational Mechanics Editorial Office, Dalian University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Rolling Stock (1002-7602) is the property of Rolling Stock Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The ability of energy dissipation from earthquake force in a controlled and iterative manner will play a vital role in maintaining structural reliability for various forces. High force-to-volume (HF2V) extrusion damper is a promising technology with simple designs, high damping force and achieving design requirements. This paper develops HF2V extrusion damper with multiple toothing configuration for seismic application. The experimental verification has been undertaken on lead extrusion dampers with various frequency range of 0.5 to 2 Hz. The maximum load-carrying capacity is 10.48 kN with strokes up to 5mm are observed with hysteresis loop with some recentering capability has a stiffness value up to 2*106 N/m, and force levels up to 2-10 kN. The maximum load carrying capacity for time history loading for Northridge earthquake is 11.57 kN. The overall findings suggest that silicone sealant may be employed to build and characterize extrusion dampers with maximum energy dissipation and high force/volume interactions. The suggested device may be a potentially effective way to provide additional energy dissipation to structures in seismic zones, according to the mechanical characteristics to the frequency. Additionally, the system can withstand for earthquake time histories, and ensuring maintenance-free operation even in the midst of frequent ground vibration. [ABSTRACT FROM AUTHOR]

Background. The purpose of this work is to describe the proposed design of a spatial damper integrated into the bed of a desktop machine to increase the rigidity and damping capabilities of the “machine – device – instrument – workpiece” system, and substantiate the feasibility of its use from a technical point of view. The relevance of the study is due to the problematic nature of ensuring and increasing the rigidity of metalworking machines, especially small ones. When designing any machine tool capable of processing hard and durable materials, the issues of rigidity and vibration damping of the “machine – device – instrument – workpiece” system are critical. Since the main load-bearing unit of the machine is its bed, the emphasis was placed on this particular unit of the machine. Materials and methods. To justify the feasibility of using the proposed technical solution, an analysis of the mathematical model of the machine and its design diagram was performed based on information about the metal consumption and design features of the spatial damper under consideration. The source material for the study is the previously developed design of the frame and the scientific groundwork of the authors in this area. Results. It has been shown that the use of spatial dampers in the bed of a table-top machine is technically feasible and has a positive effect on the stiffness and damping of the entire “machine – device – instrument – workpiece” system. Conclusions. The proposed approach will make it possible to manufacture desktop machines with the required combination of damping and stiffness indicators without significant changes in their weight and dimensions and to improve the accuracy of machine operation.

This article presents research into the feasibility of applying a nonlinear damper of a new conceptual structure. The key component of the damper is a circular membrane with slits that can move in a cylinder filled with viscous fluid. When an external load is applied to the damper, the membrane deforms, opening the slits. The flow of viscous fluid through the slits generates a damping force. The phenomenological model of the damper is based on the notion that the slit membrane moves according to the fundamental axisymmetric vibration mode of a circular membrane. The slit membrane blocks the entire radius of the pipe in the state of equilibrium when all slits are closed. As the membrane moves, the opening area of the slits varies depending on its deformation. This gives a nonlinear damping characteristic. The damping constant depends on the input displacement and velocity, which is the reason for the nonlinearity of the damping characteristic. From the phenomenological model, the nonlinear characteristic of the drag force is obtained. The performance of the damper is simulated using a mass–spring–damper system. Two cases of harmonic excitation and impulse excitation are analyzed. The results show that, using the slit membrane damper, the suppression of dynamic loads is more effective compared to a conventional linear damper.

To reduce the cost of small wind turbines, a prototype of a butterfly wind turbine (6.92 m in diameter), a small vertical-axis type, was developed with many parts made of extruded aluminum suitable for mass production. An overspeed control system with movable arms that operated using centrifugal and aerodynamic forces was installed for further cost reduction. Introducing this mechanism eliminates the need for large active brakes and expands the operating wind speed range of the wind turbine. However, although the mechanism involving the use of only bearings is simple, the violent movement of the movable arms can be a challenge. To address this in the present study, dampers were introduced on the movable arm rotation axes to improve the movement of the movable arms. To predict the behavior of a movable arm and the performance of the wind turbine with the mechanism, a simulation method was developed based on the blade element momentum theory and the equation of motion of the movable arm system. A comparison of experiments and predictions with and without dampers demonstrated qualitative agreement. In the case with dampers, measurements confirmed the predicted increase in the rotor rotational speed when the shorter ailerons installed perpendicularly to the movable arms were used to achieve the inclination. Field experiments of the generated power at a wind speed of 6 m/s (10 min average) showed relative performance improvements of 11.4% by installing dampers, 91.3% by shortening the aileron length, and 57.6% by changing the control target data. The movable arm system with dampers is expected to be a useful device for vertical-axis wind turbines that are difficult to control.