Nondimensional Damping Analysis of Flow-Mode Magnetorheological and Electrorheological Dampers

Aerospace ◽  
2003 ◽  
Author(s):  
Wei Hu ◽  
Norman M. Wereley
Keyword(s):  
Magnetic Circuit ◽  
Design Method ◽  
Damping Coefficient ◽  
Flow Mode ◽  
Shear Mode ◽  
Number Range ◽  
Bingham Plastic ◽  
Bingham Number ◽  
Er Damper ◽  
The Relationship

In an effort to develop a Magnetorheological (MR) and Electrorheological (ER) damper initial design method, a quasi-steady relationship between force and velocity exhibited by a flow-mode MR/ER damper is developed based on a Bingham plastic model and a parallel plate assumption. A nondimensional damping coefficient is described as a nonlinear explicit function of an independent nondimensional Bingham number. Since the nondimensional damping coefficient is not a simple analytical function of the Bingham number, a uniform rational approximation approaches is used to determine the relationship between nondimensional damping coefficient and Bingham number. Approximate linear relationship is obtained in a certain Bingham number range. Thus, the quasi-steady flow mode damping approximately consists of a controllable damping and a linear viscous or post-yield damping, which is similar to the behavior of a shear mode damper. The effect on the nondimensional damping coefficient due to the magnetic circuit is also considered by introducing a ration of the length of active region to the total flow gap length.

A Preliminary Parametric Study of Electrorheological Dampers

1994 ◽  
Vol 116 (3) ◽  
pp. 570-576 ◽  
Author(s):  
Z. Lou ◽  
R. D. Ervin ◽  
F. E. Filisko
Keyword(s):  
Cross Section ◽  
Mixed Mode ◽  
Flow Mode ◽  
Shear Mode ◽  
Zero Field ◽  
Damping Force ◽  
Bingham Plastic ◽  
Control Effectiveness ◽  
Er Damper ◽  
Er Fluid

In approaching the design of an electrorheology-based, semi-active suspension, the electrorheological component (ER damper) can be built as either a flow-mode, shear-mode, or mixed-mode type of damper. The source of damping force in the flow-mode is exclusively from flow-induced pressure drop across a valve, while that in the shear-mode is purely from the shear stress on a sliding surface. The dynamics of the fluid flow are included in the derivation of the zero-field damping forces. The control effectiveness is found to be strongly related to the dynamic constant (which is proportional to the square root of the vibration frequency) and, for shear-and flow-mode dampers, the ratio of the piston area to the cross-section of the ER control gap. To achieve the same performance, a flow-mode ER damper is not as compact and efficient as a shear-mode ER damper. With the same ER damping force, a mixed-mode damper is more compact than a shear-mode damper. However, the mixed-mode damper does not have as a low zero-field damping force as the shear-mode damper. The analysis is based on the assumption that the ER fluid is Bingham plastic.

BINGHAM AND RESPONSE CHARACTERISTICS OF ER FLUIDS IN SHEAR AND FLOW MODES

2001 ◽  
Vol 15 (06n07) ◽  
pp. 1017-1024 ◽  
Author(s):  
H. G. LEE ◽  
S. B. CHOI ◽  
S. S. HAN ◽  
J. H. KIM ◽  
M. S. SUH
Keyword(s):  
Electric Fields ◽  
Flow Mode ◽  
Shear Mode ◽  
Damping Force ◽  
Response Characteristics ◽  
Operating Modes ◽  
Field Dependent ◽  
Different Temperatures ◽  
Er Damper ◽  
Er Fluid

This paper presents field-dependent Bingham and response characteristics of ER fluid under shear and flow modes. Two different types of electroviscometers are designed and manufactured for the shear mode and flow mode, respectively. An ER fluid consisting of soluble chemical starches (particles) and silicon oil is made and its field-dependent yield stress is experimentally distilled at two different temperatures using the electroviscometers. Time responses of the ER fluid to step electric fields are also evaluated under two operating modes. In addition, a cylindrical ER damper, which is operated under the flow mode, is adopted and its measured damping force is compared with predicted one obtained from Bingham model of the shear and flow mode, respectively.

NONDIMENSIONAL QUASISTEADY ANALYSIS OF A MAGNETORHEOLOGICAL DASHPOT DAMPER

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1584-1590 ◽  
Author(s):  
YOUNG-TAI CHOI ◽  
NORMAN M. WERELEY
Keyword(s):  
Mixed Mode ◽  
Performance Metrics ◽  
Fluid Velocity ◽  
Hydraulic Cylinder ◽  
Flow Mode ◽  
Damping Capacity ◽  
Shear Mode ◽  
Stress Profile ◽  
Cylinder Wall ◽  
Bingham Plastic

This paper addresses nondimensional analysis of a magnetorheological (MR) dashpot damper. An MR dashpot damper consists of a loosely fitting piston within a hydraulic cylinder or reservoir of MR fluids. The fluid flow within such a damper presents both Poiseuille (flow mode or pressurized flow through the duct) and Couette (shear mode or shear flow due to relative motion between piston and hydraulic cylinder wall) simultaneously. Thus, an MR dashpot damper, which mixes both shear and flow modes of behavior, is called a mixed mode damper. In this study, a quasi-steady analysis of MR dashpot dampers was revisited based on the utilization of the Bingham-plastic constitutive model to assess performance metrics such as damping capacity. For the mixed mode MR damper, key physical quantities are derived: fluid velocity profile, shear stress profile, and damping coefficient. In addition, the plug thickness equation to characterize the relationship between the Bingham number and the plug thickness is constructed. Through computer simulation, damping characteristics of the mixed mode MR dashpot damper are evaluated and compared to the flow mode case.

Quasi-Steady Analysis of a Magnetorheological Dashpot Damper

Aerospace ◽  
2004 ◽  
Author(s):  
Young-Tai Choi ◽  
Norman M. Wereley
Keyword(s):  
Mixed Mode ◽  
Shear Flows ◽  
Performance Metrics ◽  
Fluid Velocity ◽  
Flow Mode ◽  
Damping Capacity ◽  
Stress Profile ◽  
Bingham Plastic ◽  
Bingham Number ◽  
Moving Wall

This paper addresses quasi-steady analysis of a magnetorheological (MR) dashpot damper. MR dashpot dampers show mixed fluid mode of flow and shear flows since a dashpot inside dampers works as a piston and a moving wall simultaneously. In this study, quasi-steady analysis of MR dashpot dampers has developed based on the utilization of the Bingham-plastic constitutive model to assess performance metrics such as damping capacity. For the mixed mode MR damper that is the sums of flow and shear flows, fluid velocity profile, shear stress profile, and damping coefficient are theoretically derived. In addition, the preyield thickness equation to characterize the relationship between the Bingham number and the preyield thickness is constructed. Through computer simulation, damping characteristics of the mixed mode MR dashpot damper are evaluated and compared with flow mode case.

Analysis of magnetic force and dynamic characteristic for non-contact permanent magnet linear drive device

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1337-1345
Author(s):  
Chuan Zhao ◽  
Feng Sun ◽  
Junjie Jin ◽  
Mingwei Bo ◽  
Fangchao Xu ◽  
...  
Keyword(s):  
Finite Element ◽  
Permanent Magnet ◽  
Dynamic Characteristic ◽  
Driving Force ◽  
Magnetic Circuit ◽  
Response Speed ◽  
Computation Method ◽  
Element Analysis ◽  
Element Simulation ◽  
The Relationship

This paper proposes a computation method using the equivalent magnetic circuit to analyze the driving force for the non-contact permanent magnet linear drive system. In this device, the magnetic driving force is related to the rotation angle of driving wheels. The relationship is verified by finite element analysis and measuring experiments. The result of finite element simulation is in good agreement with the model established by the equivalent magnetic circuit. Then experiments of displacement control are carried out to test the dynamic characteristic of this system. The controller of the system adopts the combination control of displacement and angle. The results indicate that the system has good performance in steady-state error and response speed, while the maximum overshoot needs to be reduced.

The Relationship Between Frictional Resistance and Roughness for Surfaces Smoothed by Sanding

2002 ◽  
Vol 124 (2) ◽  
pp. 492-499 ◽  
Author(s):  
Michael P. Schultz
Keyword(s):  
Reynolds Number ◽  
Frictional Resistance ◽  
Resistance Coefficient ◽  
Polished Surface ◽  
Average Height ◽  
Freestream Velocity ◽  
Number Range ◽  
Test Fixture ◽  
Plate Length ◽  
The Relationship

An experimental investigation has been carried out to document and relate the frictional resistance and roughness texture of painted surfaces smoothed by sanding. Hydrodynamic tests were carried out in a towing tank using a flat plate test fixture towed at a Reynolds number ReL range of 2.8×106−5.5×106 based on the plate length and freestream velocity. Results indicate an increase in frictional resistance coefficient CF of up to 7.3% for an unsanded, as-sprayed paint surface compared to a sanded, polished surface. Significant increases in CF were also noted on surfaces sanded with sandpaper as fine as 600-grit as compared to the polished surface. The results show that, for the present surfaces, the centerline average height Ra is sufficient to explain a large majority of the variance in the roughness function ΔU+ in this Reynolds number range.

Minimum Energy Control of Multibody Systems Utilizing Storage Elements

2009 ◽  
Author(s):  
Werner Schiehlen ◽  
Makoto Iwamura
Keyword(s):  
Multibody Systems ◽  
Optimal Trajectory ◽  
Design Method ◽  
Equations Of Motion ◽  
Minimum Energy ◽  
Operating Time ◽  
Minimum Energy Control ◽  
Robot Systems ◽  
Optimal Design Method ◽  
The Relationship

In this paper, we consider the problem to minimize the energy consumption for controlled multibody systems utilizing passive elastic elements for energy storage useful for robot systems in manufacturing. Firstly, based on the linearized equations of motion, we analyze the relationship between the consumed energy and the operating time, and the optimal trajectory using optimal control theory. Then, we verify the analytical solution by comparing with the numerical one computed considering the full nonlinear dynamics. After that we derive a condition for the operating time to be optimal, and propose the optimal design method for springs. Finally, we show the effectiveness of the design method by applying it to a 2DOF manipulator.

Different Types of Microbial Fuel Cell (MFC) Systems for Simultaneous Electricity Generation and Pollutant Removal

2015 ◽  
Vol 74 (3) ◽  
Author(s):  
S. M. Zain ◽  
N. L. Ching ◽  
S. Jusoh ◽  
S. Y. Yunus
Keyword(s):  
Nitrogen Removal ◽  
Continuous Flow ◽  
Electricity Generation ◽  
Pollutant Removal ◽  
Flow Mode ◽  
Oxidizing Agent ◽  
Batch Mode ◽  
Carbon And Nitrogen ◽  
Different Types ◽  
The Relationship

The aim of this study is to identify the relationship between the rate of electricity generation and the rate of carbon and nitrogen removal from wastewater using different MFC processes.  Determining whether the generation of electricity using MFC process could be related to the rate of pollutant removal from wastewater is noteworthy. Three types of MFC process configurations include the batch mode (SS), a continuous flow of influent with ferricyanide (PF) as the oxidizing agent and a continuous flow of influent with oxygen (PU) as the oxidizing agent. The highest quantity of electricity generation was achieved using the continuous flow mode with ferricyanide (0.833 V), followed by the continuous flow mode with oxygen (0.589 V) and the batch mode (0.352 V). The highest efficiency of carbon removal is also achieved by the continuous flow mode with ferricyanide (87%), followed by the continuous flow mode with oxygen (51%) and the batch mode (46%). Moreover, the continuous flow mode with ferricyanide produced the highest efficiency for nitrogen removal (63%), followed by the continuous flow mode with oxygen (54%) and the batch mode (27%).

A synergy-column envelope meshing pair profile for single screw compressors

2018 ◽  
Vol 233 (4) ◽  
pp. 1383-1391 ◽  
Author(s):  
Feilong Liu ◽  
Junhao Feng ◽  
Jia Xie ◽  
Quanke Feng ◽  
Martijn Van Den Broek ◽  
...  
Keyword(s):  
Design Method ◽  
Optimal Combination ◽  
Stable Operation ◽  
Single Screw ◽  
Tooth Width ◽  
Operational Life ◽  
Column Design ◽  
Manufacturing Methods ◽  
Operation Results ◽  
The Relationship

Multi-column envelope engaging couples have been proposed for single screw compressors to reduce the friction and prolong the operational life. However, little is mentioned about the relationship between columns at opposite sides of the star-wheel teeth. An imbalance in the lubricant film forces would appear and influence the lubrication between the tooth and the groove. During a real design process, it is necessary to try several times for each different type of compressor to find the optimal combination of columns. In part, due to the large number of columns, it also makes both manufacturing processing and product testing difficult. In this paper, a synergy-column design method and its related manufacturing methods are presented. The locations and relationships of the designed columns can be prescribed by given the tooth width. Manufacturing of the rotor and star-wheel shows the new design method can be more efficient through processing. The stable operation results prove that the synergy-column envelope meshing pair can solve the star-wheel’s wear-out problem.

scholarly journals Analysis of Post Loan Disbursement Allocation and Performance of Non-Prime Household Loan in Microfinance Banks in Kenya

2017 ◽  
Vol 03 ◽  
pp. 42
Author(s):  
Bernard Ndirangu Wachira ◽  
Humphrey Opiyo Omondi ◽  
Josphat K. Kinyanjui ◽  
◽  
◽  
...  
Keyword(s):  
Financial Management ◽  
Design Method ◽  
Wald Test ◽  
Grameen Bank ◽  
Credit Risks ◽  
Training Policy ◽  
The Government ◽  
And Performance ◽  
Descriptive Survey ◽  
The Relationship

The part played by non-prime household loans in improving the lives of many people who cannot afford collateral globally cannot be ignored. Many Microfinance Banks in many economies worldwide have tried to maintain the Grameen Bank Model of granting microloans, mainly non-prime household loans. However, the credit risks associated with this initiative hamper the pace at which the granting of this credit facility is expected to grow. This study intends to explore the relationship between the post loan disbursement allocation and the performance of non-prime household loans in the Microfinance Banks in Kenya. The theory associated to this study is the Credit Risk Theory. This theory, which is regarded as credit structural theory, was developed by Merton in 1972. The descriptive survey research design method was applied, and the sample size was 150 respondents. The data-collection tool used was a questionnaire. A logistic regression analysis was conducted for the purpose of predicting non-prime household performance in the Microfinance Banks using training budget, recoveries budget, percentage of training budget, and percentage of recoveries budget as predictors. The Wald test shows that training budget, recoveries budget, and percentage of training budget were good predictors, making a significant contribution to prediction. The percentage of budget on recoveries was not a significant predictor. The Microfinance Banks should enhance the performance of non-prime household loans through capacity building to the borrowers and educate the borrowers on dangers of enforced loan recoveries. The government, through the Central Bank of Kenya, should have a training policy for the Microfinance Banks so that they can enlighten the borrowers on proper financial management to avoid conflicts with borrowers during loan recoveries.

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