Cylindrical Damper Research Articles

Влияние геометрической формы демпфера на эффективность работы ультразвукового пьезоэлектрического преобразователя

Purpose of the work: To evaluate the influence of the geometric shape of the damper in the form of a truncated cone on the efficiency of the ultrasonic piezoelectric transducer. Materials and methods: Numerical and experimental modeling of the processes of propagation of ultrasonic signals in the damper of an ultrasonic transducer was used. Results: A damper in the form of a truncated cone is considered, the generatrix of which has an angle of inclination α with respect 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 contributes to an increase in the path of the wave in the damper material due to numerous reflections inside it. A criterion for the efficiency of the damper is proposed. Theoretically and experimentally, the optimal (from the point of view of the efficiency of the damper) value of the angle α was determined. The technology of its manufacture is described. A satisfactory agreement between the results of theoretical and experimental studies was noted. Conclusion: The efficiency of a conical damper filled with a mixture of tungsten powder and KDA resin in a 1:1 ratio is higher than that of a cylindrical damper. A damper made from such a mixture can be effectively used in the manufacture of converters with a frequency of at least 2.5 MHz. For lower frequencies, it is required to select a different damping composition with a different filler or with a different ratio of its constituent components. The maximum efficiency of a cone damper is achieved when the cone generatrix is tilted α = 64…66.

Study on seismic performance of functionally integrated cylindrical steel damper bearing with energy dissipation and spacing

The bridge bearing serves as a crucial constituent that can exert a substantial influence on the seismic performance of the bridge structure. When subjected to seismic events, conventional fixed-type bearings transmit considerable seismic forces, leading to detrimental effects on the bridge piers. The damage incurred by the fixed-type bearings can result in significant relative displacement between the pier and girder, which can potentially contribute to the unseating. To effectively control the seismic damage to bridge piers and the relative displacements between the pier and girder, as well as to facilitate controllable design of bridge seismic behaviors, a novel functional integration approach was developed: the functionally integrated cylindrical steel damper bearing (FICSDB). The FICSDB incorporated certain functionalities, such as seismic isolation, energy dissipation, and displacement limitation. Specifically, following the constructional details and operational mechanisms of the FICSDB, the mechanical model was initially derived. Subsequently a series of cyclic shear tests were conducted on the FICSDB. Certain results were obtained as follows. (1) The bearing’s sliding performance remained relatively stable. (2) The cylindrical damper effectively achieved the desired objectives of energy dissipation and spacing, thereby exhibiting exceptional fatigue resistance. (3) The components demonstrated close cooperation, which ensured the overall stability and controllability of the FICSDB’s mechanical behavior. (4) The effectiveness of the FICSDB was validated through numerical calculations with the application of a continuous girder bridge as a case study. The results revealed that, in comparison to traditional fixed-type bearings, employing the FICSDB significantly reduced internal forces exerted on the bridge piers during rare seismic events. Additionally, when compared to conventional isolation bearings, the FICSDB realized the excellent minimization of the relative displacement between the pier and girder. Therefore, the FICSDB can enable the dual control of the pier damage and unseating, thereby facilitating the controlled design of bridge seismic behaviors.

Analysis of Cylindrical Damper Effects on Turbine Meters Accuracy in a Pulsating CNG Suction Line: An Optimal Design through CFD Simulations

Turbine meters are used in compressed natural gas (CNG) stations in abundance to measure the volumetric flow rate of the inlet gas. These types of meters are very sensitive to oscillating and pulsating flows. When the station’s reciprocating compressor starts to work, due to the piston and valve performance, pulsating flow will create in the suction line and downstream of turbine meter. This pulsation makes false pulses in the meter and finally makes difference between the measured gas flow from the metering of the gas company and the amount of gas that has been sold at the station. In this study, numerical simulation of dampeners has been investigated after turbine meter and before entering gas to compressor. The goal is eliminating or reducing the effects of operating compressor in CNG station on turbine meter and reducing measurement errors. Numerical simulation of dampener was investigated by Ansys-Fluent CFD software for a CNG station with the gas inlet pressure 250 psi, inlet and outlet pipe diameter of 2 inches. In this study, several parameters such as (1) height-to-diameter ratio in the cylinder, (2) distance between dampener and compressor, and (3) volume-to-minimum volume ratio according to API 618, have been checked. The numerical results show that by increasing height-to-diameter ratio up to 3, the pulsating amplitude on Plane 1 will be reduced, and this is the best ratio according to the present results. Also, by increasing the outlet pipe length, the pressure pulsation amplitude decreases from 3.4% of pressure line in 2 m length to 0.7% in 5 m length. Moreover, the results showed 2.4% increase and 1.9% decrease in the maximum and minimum pressure for CV = 1 and CV = 16.7, respectively. Comparing fluent numerical method with previous studies shows less than 2% difference that demonstrates the validity and reliability of present investigation.

On the explicit dynamics implementation and validation of partitioned rate-type constitutive relation for dampers

We propose a simple 3D nonlinear rate-type constitutive relation with just three parameters for elastomeric dampers capable of emulating double-shear data in frequency and strain sweep mode. The nonlinear relation derived using two scalar functions, namely Helmholtz free energy and the rate of dissipation function [1], result in a partitioned constitutive relation: Cauchy stress tensor is described in terms of the left Cauchy-Green stretch tensor and a tensor describing instantaneous elastic response, and the evolution equation for the instantaneous elastic response is derived by maximizing the rate of dissipation function. A compressible version of this model is implemented in Abaqus® The constitutive relation and the implementation are validated by comparing with known semi-inverse solutions obtained by specializing rate-type relation to special deformations. Material parameters are obtained for dampers made of synthetic and natural rubber by fitting the predictions of the model with that of double shear data. By using the same parameters, three dimensional simulations of a cylindrical damper subjected to sinusoidal force akin to that of an unbalanced machinery predict different hysteresis curves in compression/tension and shear. To that end, we show that the non-linear 3 parameter model is one of the simple models that can be formulated within the thermodynamic framework which can predict the inherent non-linearity of the damper operating under combined harmonic loading situations. A robust implementation (VUMAT) of the developed model is included with the article. We believe that this can aid engineers in tailoring dampers for its controlled dissipation across multiple modes of deformation as well as academicians in adding more value by building and implementing sophisticated models within this framework.

Collapsible fluid-filled fabric shock absorber with constant force

Energy absorption is an important challenge shared by multiple different industries including manufacturing, transportation, and protective equipment. This paper presents a novel shock absorption system based on woven fabrics designed to fully collapse and absorb energy at a near-minimum force level. The proposed system exerts an approximately constant force across different impact velocities. This system utilizes a fixed-orifice hydraulic shock absorber with variable contact area over its displacement to provide a nearly-constant force which scales with impact energy. Using analytical fluid dynamics, the contact area needed to produce a constant minimum force is derived. A finite element model of this shock absorber is created to validate the concept. Different impact conditions are simulated. The results confirm that the proposed fabric shock absorber is capable of producing a nearly-constant force across different impact energies. In simulation, the fabric shock absorber follows the ideal constant force profile with an averaged efficiency of 77.8% ± 3.4% which is far above standard foams which have efficiency of only approximately 20%–40%. The proposed system is compared with a cylindrical damper to show performance improvements gained through variable area geometry. Potential applications of this technology include soft devices for space-constrained applications such as contact sport helmets.

On the Efficiency of a Conical Underplatform Damper for Turbines

Abstract Underplatform dampers (UPDs) are commonly used in aircraft engines to limit the risk of high-cycle fatigue of turbine blades. The latter is located in a groove between two consecutive blades. The dry friction contact interface between the damper and the blades dissipates energy and so reduces the vibration amplitudes. Two common geometries of dampers are used nowadays, namely wedge and cylindrical dampers, but their efficiency is limited when the blades have an in-phase motion (or a motion close to it), since the damper tends to have a pure rolling motion. The objective of this study is to analyze a new damper geometry, based on a conical shape, which prevents from this pure rolling motion of the damper and ensures a high kinematic slip. The objective of this study is to demonstrate the damping efficiency of this geometry. Hence, in a first part, the kinematic slip is approximated with analytical considerations. Then, a nonlinear dynamic analysis is performed, and the damping efficiency of this new geometry is compared to the wedge and the cylindrical geometries. The results demonstrate that the conical damper has a high damping capacity and is more efficient and more robust than the two others.

Evaluation of 2D concentrically braced frames with cylindrical dampers subjected to near-field earthquake ground motions

Evaluation of 2D concentrically braced frames with cylindrical dampers subjected to near-field earthquake ground motions

Direct measurement of the damping and stiffening capabilities of cylindrical underplatform dampers

The paper focuses on the cylindrical underplatform damper, a friction damping device widely used in power generation turbines. The first goal of the paper is to estimate the stiffness and damping contribution of cylindrical dampers interposed between adjacent blades vibrating along a typical in-phase mode. For the first time, the damper characterization is performed through the direct measurement of contact forces and platform displacements.Measurements show that the damper does not introduce damping or stiffness if the two platforms, with which the damper is in contact, share the same angles (i.e. blade with symmetrical platform) and are vibrating in-phase. This is an adequate design choice if only the damper sealing function is required, while changes to the disk dynamics are not desired. The damper produces a small stiffening effect only if the two adjacent platforms have different angles. These findings are confirmed by an analytical derivation performed on the basis of a simple yet effective damper model.The damper numerical model requires parameters which may be calibrated, i.e. the cylinder-on-flat tangential contact stiffness. The second goal of the paper is to use the experimental evidence on contact forces and platform displacements to estimate these parameters for different centrifugal loads using a purposely developed technique. These values are compared with those obtained at an identically designed contact interface on a curved flat damper (i.e. cylindrical damper with a flattened side). The differences found in the calibration parameters show that the local stiffnesses depends not only on the local geometry of the contact but also on the damper kinematics.

Seismic response reduction of a three-story building by an MR grease damper

This paper describes an application of magneto- rheological (MR) grease dampers as seismic dampers for a three-story steel structure. MR fluid is widely known as a smart material with rheological properties that can be varied by magnetic field strength. This material has been applied to various types of devices, such as dampers, clutches, and engine mounts. However, the ferromagnetic particles dispersed in MR fluid settle out of the suspension after a certain interval because of the density difference between the particles and their carrier fluid. To overcome this defect, we developed a new type of controllable working fluid using grease as the carrier of magnetic particles. MR grease was introduced into a cylindrical damper, and the seismic performance of the damper was subsequently studied via numerical analysis. The analysis results of the MR grease damper were compared with those of other seismic dampers. We confirmed that the MR grease damper is an effective seismic damper.

Vibration Control by a Shear Type Semi-active Damper Using Magnetorheological Grease

This paper describes semi-active vibration control by a controllable damper with high reliability and wide dynamic range using magnetorheological (MR) grease. Some types of cylindrical controllable dampers based on pressure difference between chambers in the dampers using “MR fluid”, whose rheological properties can be varied by applying a magnetic field, have been reported as a semi-active device. However, there are some challenging issues of them. One is to improve dispersion stability. The particles dispersed in MR fluid would make sedimentation after a period. Another is to expand dynamic range. Since cylindrical dampers require sealing elements because of pressure difference in the dampers, the dynamic range between the maximum and minimum damping force according to a magnetic field is reduced. In this study, a controllable damper using the MR effect was proposed and its performance was experimentally verified to improve the dispersion stability by using “MR grease”, which includes grease as the carrier of magnetic particles, and to expand the dynamic range by adopting a shear type structure not requiring sealing elements. Furthermore, semiactive vibration control experiments by the MR grease damper using a simple algorithm based on the skyhook damper scheme were conducted and its performance was investigated.

526 自立型構造物に適用する二重円筒型ダンパを備えた免震装置のスケール効果に関する基礎検討(GS-10 流体関連振動(2))

526 自立型構造物に適用する二重円筒型ダンパを備えた免震装置のスケール効果に関する基礎検討(GS-10 流体関連振動(2))

Vibration control of a structure using Magneto-Rheological grease damper

This paper describes an application study of Magneto-Rheological (MR) grease damper to a structure with three stories. MR fluid is known as one of successful smart materials whose rheological properties can be varied by magnetic field strength, and has been applied to various kinds of device such as dampers, clutches, engine mounts, etc. However, ferromagnetic particles dispersed in MR fluid settle out of the suspension after a certain interval due to the density difference between the particles and their career fluid. To overcome this defect, we have developed a new type of controllable working fluid using grease as the career of magnetic particles. Network of thickener in grease is expected to hold the magnetic particles and prevent them from settled down. No or little sedimentation was observed in MR grease whose characteristics could be controlled by the magnetic field strength. MR grease was introduced into a cylindrical damper and its performance was studied. As a result, it was confirmed that the damping force of MR grease damper could be controlled by the applied electric current to the coil in the cylinder of damper. Furthermore, vibration response of a three-story model structure equipped with MR grease damper was investigated experimentally, and it was shown that MR grease damper worked effectively as a semi-active damper.

412 住宅用オイルダンパの開発に関する研究 : ダンパの形状の違いについての検討

In late years, large scale earthquakes are occurring in the world. Then, control of seismic response of house is important for protection from destructive earthquakes. This paper proposes some types of oil dampers for vibration control device for two story houses. Oil damper is connected to the ceiling of the first story and fixed on the foundation. The rectangular parallelepiped damper, the cylindrical damper and the spherical damper with silicon oil are proposed. The effectiveness of oil dampers is examined by experiment and simulation. It is concluded that the peaks of the resonance curve are reduced when dampers are used.

630 磁気粘性グリースダンパによる構造物の制振

This paper describes an application study of Magneto-Rheological (MR) grease damper to a structure with three stories. MR fluid is known as one of successful smart materials whose rheological properties can be varied by applied magnetic field strength, and has been applied to various kinds of device such as dampers, clutches, engine mounts, etc. However, the sedimentation of ferromagnetic particles dispersed in MR fluid may take place due to the density difference between the particles and their career fluid. In order to overcome this defect, we developed new type of controllable working fluid using grease as the career of magnetic particles which might be held in its thickener network. No or little sedimentation was observed in MR grease whose characteristics could be controlled by the applied magnetic field strength. MR grease was introduced into a cylindrical damper and its performance was studied. As a result, it was confirmed that the damping force of MR grease damper could be controlled by the applied electric current to the coil in the cylinder. Furthermore, vibration response of a three-story model structure equipped with MR grease damper was investigated experimentally, and it was shown that MR grease damper works effectively as a semi-active damper.

207302 MRグリースの基本特性と円筒型ダンパへの応用(一般02 機械力学・制御工学10)

207302 MRグリースの基本特性と円筒型ダンパへの応用(一般02 機械力学・制御工学10)

448 MRグリースを用いた可変ダンパの基本特性と構造物への応用

A variable damper applying Magneto-Rheological (MR) Grease was designed and its performance was also investigated, and the dynamic characteristics of the model structure with MR Grease damper were measured. MR fluid is known as one of functional fluids, whose rheological properties can be controlled by the applied magnetic field strength. MR damper has attracted much attention as the semi-active control device. MR fluid is composed of micron-sized magnetic particles and a carrier oil such as mineral oil or silicon oil. But the particles dispersed in the fluid would precipitate and make sedimentation due to the difference of density. In order to reduce or avoid the sedimentation of the magnetic particles in MR fluid, grease was introduced instead of base oil and MR grease was developed. In this paper, MR grease was adapted to a cylindrical damper, and its properties were investigated. Furthermore, the frequency responses of the model structure equipped with MR Grease damper were measured.

1A13 Reduction of Vibration of Structure using Oil Damper : Examination from Simulation Method

Many houses were destroyed in destructive earthquakes in the world. Then, control of seismic response of house is important for protection from destruction. In this paper, two story houses are focused on and oil dampers of some shapes are proposed. Oil damper is connected to the ceiling of the first story and the foundation. The spherical damper, the rectangular parallelepiped damper and the cylindrical damper with silicon oil are proposed. The effectiveness of the dampers is examined experimentally. It is concluded that the peak of the frequency response function of the first vibration mode decreases and the damping ratio increases when the dampers are used. From simulation method using the analytical model, it is found that the maximum response decreases when the dampers are used.

The Effect of Thermal Boundary Condition on the Crosslink Density Distribution and the Curing Time of the Thick Cylindrical Dampers

Abstract Optimization of curing process conditions of elastomers so as to achieve a part with homogeneous network is of crucial importance. One of the indicative parameters in the curing process is state of cure (SOC) that is investigated in this study in order to verify the influence of thermal boundary conditions on the curing of a cylindrical damper based on NR.. Furthermore, the newly introduced parameter of state of reversion (SOR) is defined, and this parameter will be set as a controlling parameter in the curing time; in order to avoid the unfavorable phenomenon of thermal decomposition. In this work, the curing process is numerically modeled using a finite element code which is developed by authors and results are compared with experimental results, as a verification step for validity of the code. Employing this code, the curing process is subjected to various molding temperatures, and it is demonstrated that a constant temperature of mold for elastomeric parts of high thickness will not result in a homogeneous crosslink network, unless the curing time is very long. Therefore, a varying with time temperature profile for mold is proposed that leads to a decreased curing cycle time, while giving complete SOC at a lower SOR value, simultaneously.

20613 ダンパによる構造物の振動低減に関する研究 : 直方体・円筒形・球形を用いた場合の振幅依存性(制振・免震,一般講演)

Many houses were destroyed in destructive earthquakes in the world. Then, control of seismic response of house is important for protection from destruction. In this paper, two story houses are focused on and oil dampers of some shapes are proposed. Oil damper is connected to the ceiling of the first story and the foundation. The spherical damper the cylindrical damper and the rectangular parallelepiped damper with silicon oil are proposed. The effectiveness of the dampers is examined experimentally. It is concluded that the peak of the frequency response function of the first vibration mode decreases and depend on amplitude of excitation. dampers are used.

421 ダンパによる構造物の振動低減に関する研究 : 種々の形状のダンパの比較

Reduction of seismic response of house is an important problem for aseismic design. In this paper, spherical damper, cylindrical damper and rectangular parallelepiped damper with silicon oil is developed for reduction of seismic response of two-story house. For reduction of seismic response of two-story house, an oil damper is connected to the ceiling of the first floor and the foundation. Resonance curves are obtained for various coefficient of kinematic viscosity of silicon oil. Peak responses in resonance curves are focused on. Damping ratio and peak amplitude ratio for the first vibration mode are obtained for various forms of damper. It is found that the peak responses are reduced when dampers are used.