Colloidal Damper Research Articles

Effect of Hydrophobic Silica Nanochannel Structure on the Running Speed of a Colloidal Damper

A colloidal damper (CD) can dissipate a significant amount of vibrations and impact energy owing to the interface power that is generated when it is used. It is of great practical significance to study the influence of the nanochannel structure of hydrophobic silica gel in the CD damping medium on the running speed of the CD. The fractal theory was applied to observe the characteristics of the micropore structure of the hydrophobic silica gel by scanning electron microscopy (SEM), the primary particles were selected to carry out fractal analysis, and the two-dimensional fractal dimension of the pore area and the tortuous fractal dimension of the hydrophobic silica gel pore structure were calculated. The fractal percolation model of water in hydrophobic silica nanochannels based on the slip theory could thus be obtained. This model revealed the relationship between the micropore structure parameters of the silica gel and the running speed of the CD. The CD running speed increases with the addition of grafted molecules and the reduction in pore size of the silica gel particles. Continuous loading velocity testing of the CD loaded with hydrophobic silica gels with different pore structures was conducted. By comparing the experimental results with the calculation results of the fractal percolation model, it was determined that the fractal percolation model can better characterize the change trend of the CD running velocity for the first loading, but the fractal dimension was changed from the second loading, caused by the small amount of water retained in the nanochannel, leading to the failure of fractal characterization.

Performance Evaluation of Dampers Under Dynamic Impact Based on Magnetic Field FE and CFD

It is necessary to install a damping energy absorbing structure for a certain type of naval gun test shell without projectile belt. Applicable high-performance dampers currently include viscoelastic colloidal damper and magnetorheological damper, and two kinds of special dampers for test shells have been designed and manufactured. In order to evaluate the mechanical properties of these two dampers under dynamic impact, a one-way coupling numerical method was proposed for simulation and analysis. Quasi-static experiments were used to verify the model based on magnetic field finite element (FE) and computational fluid dynamics (CFD). The model is also characterized by passive dynamic mesh and user-defined functions (UDF) based on C language. The results showed that the CFD models of both dampers were accurate. Though the colloidal damper is simpler in structure and lower in the cost, the MR damper has more significant damping and higher energy absorption ratio under impact. Compared with colloidal damper, MR damper is characterized by long working time, multiple vortices, chaotic streamlines and more uniform temperature distribution. When the power was continuously applied, the velocity of the impacted MR damper dropped to zero within 80ms, and the piston finally stopped at a stroke of 1.3mm. The colloidal damper reset within 8ms, and the reset velocity was 1.1m/s. In this study, the performance evaluation results of the two dampers were obtained, and the latest numerical methods for the mechanical performance analysis of colloidal dampers and MR dampers under dynamic impact were provided.

Experimental investigation on a colloidal damper rendered controllable under the variable magnetic field generated by moving permanent magnets

In this work, a colloidal damper rendered controllable under variable magnetic fields is proposed and its controllability is experimentally evaluated. This absorber employs a water- based ferrofluid (FERROTEC MSGW10) in association with a liquid-repellent nanoporous solid matrix, consisted of particles of gamma alumina or/and silica gel. Control of the dynamic characteristics is obtained by moving permanent neodymium annular magnets, which are placed either on the piston head (axial magnetic field) or on the external surface of the cylinder (radial magnetic field). In order to properly select these magnets, flow visualizations inside of a transparent model damper were performed, and the quantity of the displaced liquid by the magnets through the damper's filter and through the nanoporous solid matrix was determined. Experimental data concerning variation of the magnetic flux density at the magnet surface versus the height of the magnet, and versus the target distance was collected. Based on such data, the suitable magnet geometry was decided. Then, the 3D structural model of the trial colloidal damper obtained by using Solidworks, and the excitation test rig are presented. From excitation tests on a ball-screw shaker, one confirmed larger damping abilities of the proposed absorber relative to the traditional colloidal damper, and also the possibility to adjust the damping coefficient according to the excitation type.

Experimental investigation on the dissipative and elastic characteristics of a yaw colloidal damper destined to carbody suspension of a bullet train

Yaw damper represents a major source of excitation for flexural vibration of the railway carbody. In order to reduce transmissibility of such undesired excitation, yaw damper should allow for large force transmission at low working frequencies, but should behave as vibration isolator at high working frequencies. Unfortunately, the yaw oil damper (OD), which is nowadays in service, has poor intrinsic elastic capabilities and provides damping forces varying as a power function versus the piston speed. Since colloidal damper (CD) has intrinsic elastic capabilities and larger damping forces at lower excitation frequencies, it occurs as an attractive alternative solution to traditional yaw dampers. In this work, a yaw CD destined to carbody suspension of a bullet train was designed and manufactured; then, its dynamic characteristics, produced by both the frictional and colloidal effects, were evaluated from the experimental results, obtained during horizontal vibration tests, performed on a ball-screw shaker. Compared to the corresponding classical yaw OD, the trial yaw CD allowed for: weight reduction of 31.6%; large damping force, dissipated energy and spring constant at long piston stroke under low excitation frequency; low damping force, dissipated energy and spring constant at short piston stroke under high excitation frequency. Elastic properties were justified by introducing a model for the spring constant that included the effect of pore size distribution.

Fukuoka Institute of Technology

Vehicle suspensions able to harvest electrical energy are usually using electromagnetic motor and generators. Since the bound-rebound translation has to be transformed into rotational motion by employing various mechanisms (ball screw and nut; rack and gear; hydraulic cylinder and motor, etc.), such systems are relatively complex, costly and unreliable. Alternatively, electromagnetic induction and piezoelectricity were used to produce electrical power. Such systems are cheaper and simpler, since there is no need to transform the motion. In this work, a piezoelectric stack is placed inside the cylinder of a colloidal damper. Working colloid produces a cyclical compression-decompression on the surface of the piezoelectric disks, and in this way mechanical energy recovered from the rough road excitation can be partially transformed into electrical energy. Electrical power harvestable from such system depends on the colloidal spring constant and rigidity of the piezoelectric stack that is serially mounted together with a spring in order to obtain a suspension able to support both compressive and tensile loads. From excitation tests carried on a ball-screw shaker, one determines the amount of harvestable power. Although the obtained power (1 − 100 W) is relatively modest, some applications such as, charge and recharge of a battery, or usage as electrical power source for the actuator of a fuel injection system can be considered.

Experimental investigation on a controllable colloidal damper for vehicle suspension

Experimental investigation on a controllable colloidal damper for vehicle suspension

J2230101 水ベース磁性流体と疎水化ナノ多孔質体を用いたコロイダルダンパの制御化に関する実験的研究

J2230101 水ベース磁性流体と疎水化ナノ多孔質体を用いたコロイダルダンパの制御化に関する実験的研究

1B13 Experimental investigation on a controllable colloidal damper for vehicle suspension(The 12th International Conference on Motion and Vibration Control)

1B13 Experimental investigation on a controllable colloidal damper for vehicle suspension(The 12th International Conference on Motion and Vibration Control)

3A31 Investigation on a colloidal damper rendered controllable under electric and magnetic fields(The 12th International Conference on Motion and Vibration Control)

3A31 Investigation on a colloidal damper rendered controllable under electric and magnetic fields(The 12th International Conference on Motion and Vibration Control)

B38 車両用懸架装置に関するエネルギーハーベスティングの評価(M-OS3-2 エネルギーハーベスティング,M-OS3 スマート構造システム,「海を越え,国を越え,世代を超えて!」)

Electrical and hybrid vehicles require increasingly amounts of electrical power that might be harvested from different systems, such as the vehicle suspension. A vehicle suspension able to generate electrical power transforms the kinetic energy of vertical bound-rebound movement excited by the road roughness into electrical energy. If an electromagnetic motor and generator is used to produce electrical power, the translational bound-rebound movement has to be transformed into a rotational movement, by employing an appropriate mechanism, such as: ball screw and nut; rack and gear; hydraulic cylinder and hydraulic motor, etc. Such systems are costly, complex from a structural standpoint, and have relatively low efficiency, robustness and reliability. Oppositely, if electromagnetic induction and/or piezoelectric elements are used to produce electrical power, there is no need to transform the translational bound-rebound movement. Such systems are relatively inexpensive and simpler from a structural standpoint. In this work, a piezoelectric stack is placed inside the cylinder of an oil or colloidal damper. Working fluid produces a cyclical compression-decompression on the surface of the piezoelectric disks, and in this way the mechanical energy recovered from the rough road excitation can be partially transformed into electrical energy. Piezoelectric stack is serially mounted together with a compression helical spring in order to obtain a vehicle suspension. From excitation tests performed on a ball-screw shaker one determines the power generation performances. Thus, for a piezoelectric stack consisted of 55 annular disks with an outer diameter of 60 mm, excited at a frequency of 1-10 Hz, the generated electrical power was about 1-100 W.

Modeling and Simulation of a Vehicle Suspension with Variable Damping versus the Excitation Frequency

In this work, three types of vehicle suspensions were considered and modeled as follows: oil damper mounted in parallel with a compression helical spring, for which a Kelvin-Voigt model, consisted of a dashpot and an elastic element connected in parallel is considered; colloidal damper without attached compression helical spring, for which a Maxwell model, consisted of a dashpot and an elastic element connected in series is considered; and colloidal damper mounted in parallel with a compression helical spring, for which a standard linear model, consisted of a Maxwell unit connected in parallel with an elastic element is considered. Firstly, the vibration transmissibility from the rough road to the vehicle’s body for all these suspensions was determined under the constraint that damping varies versus the excitation frequency. Then, the optimal damping and stiffness ratios were decided in order to minimize the transmissibility of vibration from the rough pavement to the vehicle’s body.

Experimental Study on the Forced Heating and Natural Cooling of a Colloidal Damper

Experimental Study on the Forced Heating and Natural Cooling of a Colloidal Damper

Experimental Study on the Forced Heating and Natural Cooling of a Colloidal Damper

Experimental Study on the Forced Heating and Natural Cooling of a Colloidal Damper

429 コロイダルダンパーによる構造物の制振設計手法の開発

Colloidal damper is a new damper which uses a principle of difference of surface extension force, which is occurred by the direction of movement of surface. Some characteristics of the colloidal damper were investigated by our group. That is, a damping characteristics of colloidal damper for the amount ratio of silica gel and water, volume of cylinder and pre-pressure of the cylinder by changing exciting frequency and displacement of a piston. By using these results, this paper presents a design method of the colloidal damper, that is, diameter and length of a cylinder, pre-pressure in the cylinder, ratio of silica-gel and water. In order to show a flow of this design method, suspension of car which is composed by colloidal damper and spring, is presented.

430 コロイダルダンパーの強制加熱・自然冷却に関する実験的研究

430 コロイダルダンパーの強制加熱・自然冷却に関する実験的研究

Experimental Study on the Thermal Characteristics of a Colloidal Damper

Lately, ecological and intelligent colloidal dampers based on the liquid penetration/exudation in/from lyophobic nanoporous solids were proposed. Although colloidal dampers could be attractive for various applications, they are still under research, since some unexpected findings await satisfactory explanation. For instance, colloidal dampers are able to dissipate large amounts of mechanical energy without significant heating, and such result is surprising since traditional absorbers transform almost integrally the dissipated energy into heat. In this work, using a digital infrared-camera, the temperature distribution on the external surface of a colloidal damper is recorded versus the working time and the positions of the main heat sources are identified. Such experiments allow evaluation of the temperature inside the colloidal damper's working cylinder and the absorber's generated heat. Introducing the colloidal damper inside of an incubator, variation of the hysteresis shape and dissipated energy versus the working temperature can be found. From such experimental results, ratio of the generated heat to the dissipated energy is evaluated.

コロイダルダンパーの熱特性に関する実験的研究(<特集>D&D2009)

Lately, ecological and intelligent colloidal dampers based on the liquid penetration/exudation in/from lyophobic nanoporous solids were proposed. Although colloidal dampers could be attractive for various applications, they are still under research, since some unexpected findings await satisfactory explanation. For instance, colloidal dampers are able to dissipate large amounts of mechanical energy without significant heating, and such result is surprising since traditional absorbers transform almost integrally the dissipated energy into heat. In this work, using a digital infrated-camera, the temperature distribution on the external surface of a colloidal damper is recorded versus the working time and the positions of the main heat sources are identified. Such experiments allow evaluation of the temperature inside the colloidal damper's working cylinder and the absorber's generated heat. Introducing the colloidal damper inside of an incubator, variation of the hysteresis shape and dissipated energy varsus the working temperature can be found. From such experimental results, ratio of the generated heat to the dissipated energy is evaluated.

523 分子動力学を用いたコロイダルダンパのシミュレーション(各種ダンパの設計,OS-3 ダンピング,総合テーマ「伝統を,未来へ!」)

This paper presents on a new damping element called the colloidal damper which is used a principle of surface extension force in nano pore of silica gel. Behavior of water in the pore is investigated using the molecular dynamics. Dissipation energy of the colloidal damper is concerned with the contact angles of water in the pore. So the contact angles are calculated for changing parameters, i.e. size of the pore, length of the hydrophobic material, velocity (pressure) of water flows into the pore. Then these results are compared with the experimental ones.

208 自動車懸架装置用コロイダルダンパーの最適設計に関する研究

208 自動車懸架装置用コロイダルダンパーの最適設計に関する研究

G1000-2-6 アクティブ制御コロイダルダンパーの減衰特性及び弾性特性に関する研究(機械力学・計測制御部門一般講演(2):振動,社会変革を技術で廻す機械工学)

An active control colloidal damper (ACCD), which is able to change its damping and elastic characteristics according to a specific type of external excitation is investigated. Control of the damping coefficient and spring constant is achieved by using a pressure controlling device, i.e., either by using a pump equipped with a servo-valve to adjust the pre-pressruization level of the ACCD cylinder, or by using an irradiating device to adjust the diameter of the silica nanopores (adjustment of the lyophobic coating thickness). Area of the recorded hysteresis gives information on the damping characteristics, and the slope of the central line of the same hysteresis gives information on the elastic characteristics. By increasing the pre-pressure or by decreasing the diameter of silica nanopores, the spring coefficient increases. Optimum pre-pressurization level to maximize the dissipation is found and the sensitivity of ACCD is evaluated