• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.784-787
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• 2003

Electrorheological(ER) and magnetorheological(MR) fluid-based dampers are typically analyzed using Bingham-plastic shear model under quasi-steady fully developed flow conditions. A Herschel-Bulkley constitutive shear flow relationship is that the linear shear stress vs. strain rate behavior of Bingham model is replaced by a shear stress that is assumed to be proportional to a power law of shear rate. This power is called the flow behavior index. Depending on the value of the flow behavior index number, varying degrees of post-yield shear thickening or thinning behavior can be analyzed. But it is not practical to analyze the damping force in a flow mode damper using Herschel-Bulkley model because it is needed to solve a polynomial equation. A useful guide is suggested to analyze the damping force in a damper using the Herschel-Bulkley model.

• Geotechnical Engineering
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• v.13 no.5
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• pp.133-144
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• 1997

It was proved from the viscosity test for deposits of debris flows(Kim and Seo, 1997) that the property of debris flows could be represented as Bingham plastic model. Based on this bahavior, numerical analysis for the movement of debris flows is carried out by using a computer progran Polyflow which huts been developed for the analysis of the behavior of non-Newtonian fluid. The numerical results obtained from two sites agree well with the movement predicted by an empirical formula. It can be concluded, therefore. that this scheme can be used for the analysis of the movement of debris flow.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.4
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• pp.1227-1240
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• 2014

Abandoned mines often cause environmental problems, such as alteration of landscape, metal contamination, and landslides due to a heavy rainfall. Geotechnical and rheological tests were performed on waste materials corrected from Imgi waste rock dump, located in Busan Metropolitan City. Debris flow mobility was examined with the help of 1-D BING model which was often simulated in both subaerial and subaqueous environments. To determine flow curve, we used a vane-penetrated rheometer. The shear stress (${\tau}$)-shear rate (${\dot{\gamma}}$) and viscosity(${\eta}$)-shear rate (${\dot{\gamma}}$) relationships were plotted using a shear stress control mode. Well-known rheological models, such as Bingham, bilinear, Herschel-Bulkley, Power-law, and Papanastasiou concepts, were compared to the rheological data. From the test results, we found that the tested waste materials exhibited a typical shear shinning behavior in ${\tau}$-${\dot{\gamma}}$ and and ${\eta}$-${\dot{\gamma}}$ plots, but the Bingham behavior is often observed when the water contents increased. The test results show that experimental data are in good agreement with rheological models in the post-failure stage during shearing. Based on the rheological properties (i.e., Bingham yield stress and viscosity as a function of the volumetric concentration of sediment) of waste materials, initial flowing shape (5 m, 10 m, and 15 m) and yield stress (100 Pa, 200 Pa, 300 Pa, and 500 Pa) were input to simulate the debris flow motion. As a result, the runout distance and front velocity of debris flow are in inverse propositional to yield stress. In particular, when the yield stress is less than 500 Pa, most of failed masses can flow into the stream, resulting in a water contamination.

• Journal of the Korean Geotechnical Society
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• v.27 no.6
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• pp.49-61
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• 2011

This paper presents the applicability of rheological models for describing fine-laden debris flows and analyzes the flow characteristics as a function of grain size. Two types of soil samples were used: (1) clayey soils - Mediterranean Sea clays and (2) silty soils - iron ore tailings from Newfoundland, Canada. Clayey soil samples show a typical shear thinning behavior but silty soil samples exhibit the transition from shear thinning to the Bingham fluid as shear rate is increased. It may be due to the fact that the determination of yield stress and plastic viscosity is strongly dependent upon interstructrual interaction and strength evolution between soil particles. So grain size effect produces different flow curves. For modeling debris flows that are mainly composed of fine-grained sediments (<0.075 mm), we need the yield stress and plastic viscosity to mimic the flow patterns like shape of deposition, thickness, length of debris flow, and so on. These values correlate with the liquidity index. Thus one can estimate the debris flow mobility if one can measure the physical properties.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.2 no.2
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• pp.107-113
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• 2001

This work presents field-dependent Bingham and response characteristics of MR fluids under shear and flow modes. Two different types of magneto-viscometers are designed and manufactured for the shear and flow modes. respectively. For the MR fluid to be tested, MRF-132LD of Lord co. is employed. The field-dependent yield stress is experimentally distilled at various temperatures using the magneto-viscometers. Time responses of the MR fluids to step electric fields are also evaluated under two operating modes.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1298-1302
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• 2000

Electrorheological(HER) and magnetorheologica(MR) fluids have a unique ability to increase the dynamic yield stress of the fluid substantially when electric or magnetic field is applied. ER and MR fluid-based dampers are typically analyzed using Bingham-plastic shear flow analysis under Quasi-steady fully developed flow conditions. An alternative perspective, supported by measurements reported in the literature, is to allow for post-yield shear thinning and shear thickening. To model these, the constant post-yield plastic viscosity in Bingham model can be replaced with a power-law model dependent on shear strain rate that is known as the Herschel-Bulkley fluid model. The objective of this paper is to predict the damping forces analytically in a typical ER bypass damper for variable electric field, or yield stress using Herschel-Bulkley analysis.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.6
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• pp.69-77
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• 1995

This paper presents performance investigation of a continuously variable ER(Electro-Rheological) damper for passenger vehicles. A dynamic model of the damper is formulated by incorporating electric field-dependent Bingham properties of the ER fluid. The Bingham properties are experimentally obtained through Couette type electroviscous measurement with respect to two different particle concentrations. The governing equation of the hydraulic model treating three components of fluid resistances;electrode duct flow, check valve flow and piston gap flow, is achieved via the bond graph method. A prototype ER damper is then designed and manufactured on the basis of parameter analysis. The damping forces of the system are experimentally evaluated by changing the intensity of the electric field, the particle concentration and the electrode gap.

• KSTLE International Journal
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• v.8 no.2
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• pp.21-25
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• 2007

The electrorheological effect of the suspension composed of Bismark Brown chitosan succinate as the dispersed phase in silicone oil was investigated. Bismark Brown chitosan succinate suspension showed a typical ER response (Bingham flow behavior) upon application of an electric field. The shear stress for the suspension exhibited the dependence with a factor equals to 1.84 power on the electric field. The experimental results for the suspension correlated with the polarization model and Bismark Brown chitosan succinate suspension behaved as an anhydrous ER fluid. On the basis of the results, Bismark Brown chitosan succinate suspension showed the ER flow behavior upon application of the electric field due to the polarizability of the branched amide and amine polar groups of the Bismark brown chitosan succinate particles.

• Korea-Australia Rheology Journal
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• v.19 no.4
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• pp.221-225
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• 2007

Electrorheological characteristics of a dispersed system of phosphorylated potato starch particles in silicone oil investigated via a rotational rheometer equipped with a high voltage generator is being reanalysized. Flow curves of these ER fluids both under several applied electric field strengths and with different degrees of phosphate substitution were mainly examined via three different rheological constitutive equations of Bingham model, De Kee-Turcotte model and our previously proposed CCJ model. Among these, the CCJ equation was found to fit the data of phosphorylated potato starch well.

• The Journal of the Petrological Society of Korea
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• v.26 no.1
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• pp.93-98
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• 2017

In this paper, we propose a lava flow simulation program to predict the range of lava flows area and thickness of lava flows during volcanic eruptions. The map information is represented as a 'cell' with observed values per fixed area such as DEM and a lava flow prediction algorithm using a cellular automata model is performed to predict the flow of lava flows. To obtain quantitative data of lava flows, fluid properties of lava flows are defined as Bingham plastic fluid and derived equation is applied to the rules of cellular automata. To verify the program, we use a 30m resolution DEM provided by USGS. We compared simulation results with real lava flows for the Pu'u'O'o crater area in Hawaii, which has erupted since May 24, 2016.