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Norman M. Wereley - One of the best experts on this subject based on the ideXlab platform.

  • Performance robustness of a magnetorheological seat suspension to temperature variations using skyhook control
    Active and Passive Smart Structures and Integrated Systems 2009, 2009
    Co-Authors: Nicholas L. Wilson, Norman M. Wereley, Young-tai Choi, Gregory J. Hiemenz
    Abstract:

    The harmonic steady-state responses of an MR seat isolator, designed and fabricated at the University of Maryland for the driver/commander seat of the Expeditionary Fighting Vehicle (EFV), are measured over a temperature range from 100°C to 1000°C, and the damper behavior is characterized using a variant of the nonlinear Bingham Plastic Model. The effect of damper self-heating on the Model parameters is investigated and the trends with temperature variation are presented. Numerical simulations are carried out to investigate seat isolation performance across a broad frequency spectrum as temperature and payload vary. Conclusions are drawn about the performance robustness to temperature variations of the semi-active skyhook control algorithm typically utilized in vibration isolation problems.

  • Rate-Dependent Elasto-Slide Model for Single and Dual Frequency MR Lag Damper Behavior
    International Journal of Modern Physics B, 2005
    Co-Authors: Norman M. Wereley
    Abstract:

    In order to capture MR lag damper behavior accurately in the context of helicopter rotor dynamic analyses, a physically motivated rate-dependent elasto-slide Model was developed based on the Bingham Plastic Model. This time-domain Model uses a rate-dependent slide and a parallel viscous damper to simulate the yield behavior of the MR fluid and uses a stiff spring in series with the slide to represent the preyield stiffness. A method of determination of the Model parameters was introduced using MR damper single frequency hysteresis data. The fidelity of the Model was justified by the good correlation between Modeling results and experimental steady-state data over a wide amplitude and moderate frequency range. Significantly, the rate-dependent elasto-slide Model is applicable in predicting response under single and dual frequency loading conditions encountered by an MR lag damper.

  • Quasi-steady axisymmetric Bingham-Plastic Model of magnetorheological flow damper behavior
    American Society of Mechanical Engineers Aerospace Division (Publication) AD, 2005
    Co-Authors: J.-h. Yoo, Norman M. Wereley
    Abstract:

    A typical magnetorheological (MR) flow mode damper consists of a piston attached to a shaft that travels in a tightly fitting hydraulic cylinder. The piston motion makes fluid flow through an annular valve in the MR damper. An electro-magnet applies magnetic field to the MR fluid as it flows through the MR valve, and changes its yield stress. An MR fluid, Modeled as a Bingham-Plastic material, is characterized by a field dependent yield stress, and a (nearly constant) postyield Plastic viscosity. Although the analysis of such an annular MR valve is well understood, a closed form solution for the damping capacity of a damper using such an MR valve has proven to be elusive. Closed form solutions for the velocity and shear stress profile across the annular gap are well known. However, the location of the plug must be computed numerically. As a result, closed form solutions for the dynamic range (ratio of field on to field off damper force) cannot be derived. Instead of this conventional theoretic procedure, an approximated closed form solution for a dampers dynamic range, damping capacity and other key performance metrics is derived. And the approximated solution is used to validate a rectangular duct simplified analysis of MR valves for small gap condition. These approximated equations are derived, and the approximation error is also provided. Copyright © 2005 by ASME.

  • comparison of damping force Models for an electrorheological fluid damper
    International Journal of Vehicle Design, 2003
    Co-Authors: S.r. Hong, Y.t. Choi, Norman M. Wereley
    Abstract:

    In this work, five different Models are proposed to predict the field-dependent damping force of an electrorheological (ER) damper and are compared. These are: the Bingham Plastic Model, the hysteretic Bingham Plastic Model, the hysteretic biviscous Model, the Bouc-Wen Model and the hydro-mechanical Model. After briefly describing the inherent characteristics of each Model, Model parameters are identified using a set of experimental data that are obtained by changing electric fields and excitation frequencies. The identified parameters are analysed and used to reconstruct the damping force – the piston velocity plot that directly indicates the hysteresis behaviour of the ER damper and compared with the measured hysteresis loop. In addition, the damping force error between the prediction and experiment is evaluated for each Model.

  • electrorheological damper analysis using an eyring constitutive relationship
    Journal of Intelligent Material Systems and Structures, 2002
    Co-Authors: Lionel Bitman, Young-tai Choi, Norman M. Wereley
    Abstract:

    We validate and assess the applicability of an Eyring constitutive Model. The Bingham Plastic Model has a zero shear rate discontinuity, which leads to inaccuracies in Modeling and simulation, and is characterized by two rheological constants for a constant field: yield stress and postyield viscosity. The Eyring Model has a smooth transition through the zero shear rate condition, and also has two rheological constants for a constant field. An electrorheological (ER) damper having a damping level comparable to a shock absorber for a small-sized passenger car damper is manufactured, and its performance is predicted using the Eyring Model. To accurately identify the rheological parameters of the Eyring Model, a parameter identification method was used. The damping force versus piston displacement and velocity behaviors of the ER damper are experimentally measured with respect to applied electric field and excitation frequency. To validate the Eyring Model, the experimental results are compared with predictions in the damping force versus piston displacement and velocity behaviors.

Youxiang Peng - One of the best experts on this subject based on the ideXlab platform.

  • unsteady analysis for oscillatory flow of magnetorheological fluid dampers based on Bingham Plastic and herschel bulkley Models
    Journal of Intelligent Material Systems and Structures, 2013
    Co-Authors: Siqi Wang, Youxiang Peng
    Abstract:

    It is known that a quasi-static analysis without considering fluid inertia is usually used for magnetorheological damper design. However, fluid inertia terms need to be incorporated into the governing Navier–Stokes equation in practical application for oscillatory or unsteady fluid flow. In this article, an unsteady flow of magnetorheological fluids within flow mode magnetorheological dampers was theoretically investigated under sinusoidal displacement excitation. Based on the governing Navier–Stokes equation, incorporating the boundary and initial conditions, central numerical velocity solutions of magnetorheological fluids within magnetorheological damping channel were developed and used to confirm the damping force using both Bingham Plastic and Herschel–Bulkley Models of magnetorheological fluids. To simplify the governing equation of Herschel–Bulkley flow, an approximation method replacing Herschel–Bulkley Model velocity with Bingham Plastic Model velocity during calculating effective viscosity shear...

  • Unsteady analysis for oscillatory flow of magnetorheological fluid dampers based on Bingham Plastic and Herschel–Bulkley Models
    Journal of Intelligent Material Systems and Structures, 2013
    Co-Authors: Siqi Wang, Youxiang Peng
    Abstract:

    It is known that a quasi-static analysis without considering fluid inertia is usually used for magnetorheological damper design. However, fluid inertia terms need to be incorporated into the governing Navier–Stokes equation in practical application for oscillatory or unsteady fluid flow. In this article, an unsteady flow of magnetorheological fluids within flow mode magnetorheological dampers was theoretically investigated under sinusoidal displacement excitation. Based on the governing Navier–Stokes equation, incorporating the boundary and initial conditions, central numerical velocity solutions of magnetorheological fluids within magnetorheological damping channel were developed and used to confirm the damping force using both Bingham Plastic and Herschel–Bulkley Models of magnetorheological fluids. To simplify the governing equation of Herschel–Bulkley flow, an approximation method replacing Herschel–Bulkley Model velocity with Bingham Plastic Model velocity during calculating effective viscosity shear...

Yoshinori Kawase - One of the best experts on this subject based on the ideXlab platform.

  • Flow of and heat transfer in turbulent slurries
    International Communications in Heat and Mass Transfer, 1992
    Co-Authors: Yoshinori Kawase, M. Moo-young
    Abstract:

    Abstract Flow of and heat transfer in turbulent slurries having a yield stress are discussed. A Bingham Plastic Model is used to describe their rheological properties. A universal velocity distribution for turbulent flow of the Bingham Plastic fluid is derived. The velocity distributions obtained using Prandtl's mixing length theory are in satisfactory agreement with the available data for Bingham Plastic fluids in pipes. On the basis of them, a theoretical correlation for heat transfer in turbulent Bingham Plastic fluids flowing pipes is obtained. It indicates that a yield stress will decrease the heat transfer rate. The proposed correlation fits the experimental data for fully developed turbulent pipe flows adequately.

  • Oxygen transfer in slurry bioreactors.
    Biotechnology and bioengineering, 1991
    Co-Authors: Yoshinori Kawase, Murray Moo-young
    Abstract:

    The oxygen transfer in bioreactors with slurries having a yield stress was investigated. The volumetric mass transfer coefficients in a 40-L bubble column with simulated fermentation broths, the Theological properties of which were represented by the Casson Model, were measured. Experimental data were compared with a theoretical correlation developed on the basis of a combination of Higbie's penetration theory and Kolmogoroff's theory of isotropic turbulence. Comparisons between the proposed correlation and data for the simulated broths show good agreement. The mass transfer data for actual mycelial fermentation broths reported previously by the authors were re-examined. Their Theological data was correlated by the Bingham Plastic Model. The oxygen transfer rate data in the mycelial fermentation broths fit the predictions of the proposed theoretical correlation.

Debadutta Das - One of the best experts on this subject based on the ideXlab platform.

  • Acacia concinna: A natural dispersant for stabilization and transportation of fly ash-water slurry
    Journal of the Taiwan Institute of Chemical Engineers, 2019
    Co-Authors: Swetashree Pattanaik, Pankaj Kumar Parhi, Debadutta Das, Akshaya Kumar Samal
    Abstract:

    Abstract The present study involves the stabilization and rheological behavior of a fly ash samples in the presence of a low cost natural dispersant saponin isolated from a plant Acacia concinna. The critical micellar concentration of the surfactant was measured and it was found to be 0.019g per cc. The rheological characteristics of the slurry had been analyzed by variation of saponin concentration, ash concentration and temperature. The data obtained were best fitted by Bingham Plastic Model in the studied ranges of concentrations 50–65%. Addition of the surfactant to the slurry reduced the surface tension of the dispersing medium water which increased wettability of the fly ash particles and reduced particle-particle interaction. Decreases in zeta potential measurement conformed that stabilization fly ash slurry is mainly due to the steric factor.

  • effect of organized assemblies part 5 study on the rheology and stabilization of a concentrated coal water slurry using saponin of the acacia concinna plant
    Energy & Fuels, 2009
    Co-Authors: Debadutta Das, Sagarika Panigrahi, P K Senapati, Pramila K Misra
    Abstract:

    The present work involves the preparation of a highly concentrated coal−water slurry employing three different low-rank coals of Indian origin having variable ash content. The formulation, rheology, and stabilization of the slurry have been investigated using saponin extracted from the seeds and pericarps (mods) of the Acacia concinna plant as a dispersant. The saponins extracted from both the seeds and pericarps of the plant are found to stabilize the slurry. The rheological characteristics of the slurry have been analyzed by varying pH and coal loading in the presence and absence of saponin. The coal−water slurry follows the Bingham Plastic Model and behaves as a non-Newtonian fluid in the presence of saponin. The stabilization of the coal−water slurry has been attributed primarily to the diminution of the coal particle−particle interaction because of steric hindrance offered by adsorbed saponin. The measurements of ζ potential, yield stress, and viscosity of coal in the presence of saponin further prov...

Siqi Wang - One of the best experts on this subject based on the ideXlab platform.

  • unsteady analysis for oscillatory flow of magnetorheological fluid dampers based on Bingham Plastic and herschel bulkley Models
    Journal of Intelligent Material Systems and Structures, 2013
    Co-Authors: Siqi Wang, Youxiang Peng
    Abstract:

    It is known that a quasi-static analysis without considering fluid inertia is usually used for magnetorheological damper design. However, fluid inertia terms need to be incorporated into the governing Navier–Stokes equation in practical application for oscillatory or unsteady fluid flow. In this article, an unsteady flow of magnetorheological fluids within flow mode magnetorheological dampers was theoretically investigated under sinusoidal displacement excitation. Based on the governing Navier–Stokes equation, incorporating the boundary and initial conditions, central numerical velocity solutions of magnetorheological fluids within magnetorheological damping channel were developed and used to confirm the damping force using both Bingham Plastic and Herschel–Bulkley Models of magnetorheological fluids. To simplify the governing equation of Herschel–Bulkley flow, an approximation method replacing Herschel–Bulkley Model velocity with Bingham Plastic Model velocity during calculating effective viscosity shear...

  • Unsteady analysis for oscillatory flow of magnetorheological fluid dampers based on Bingham Plastic and Herschel–Bulkley Models
    Journal of Intelligent Material Systems and Structures, 2013
    Co-Authors: Siqi Wang, Youxiang Peng
    Abstract:

    It is known that a quasi-static analysis without considering fluid inertia is usually used for magnetorheological damper design. However, fluid inertia terms need to be incorporated into the governing Navier–Stokes equation in practical application for oscillatory or unsteady fluid flow. In this article, an unsteady flow of magnetorheological fluids within flow mode magnetorheological dampers was theoretically investigated under sinusoidal displacement excitation. Based on the governing Navier–Stokes equation, incorporating the boundary and initial conditions, central numerical velocity solutions of magnetorheological fluids within magnetorheological damping channel were developed and used to confirm the damping force using both Bingham Plastic and Herschel–Bulkley Models of magnetorheological fluids. To simplify the governing equation of Herschel–Bulkley flow, an approximation method replacing Herschel–Bulkley Model velocity with Bingham Plastic Model velocity during calculating effective viscosity shear...