• Structural Engineering and Mechanics
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• v.86 no.2
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• pp.181-195
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• 2023

To predict the rheological behaviours along with the compressive strength of self-compacting concrete that incorporates environmentally friendly ingredients as cement substitutes, a comparative evaluation of machine learning methods is conducted. To model four parameters, slump flow diameter, L-box ratio, V-funnel time, as well as compressive strength at 28 days-a complete mix design dataset from available pieces of literature is gathered and used to construct the suggested machine learning standards, SVM, MARS, and Mp5-MT. Six input variables-the amount of binder, the percentage of SCMs, the proportion of water to the binder, the amount of fine and coarse aggregates, and the amount of superplasticizer are grouped in a particular pattern. For optimizing the hyper-parameters of the MARS model with the lowest possible prediction error, a gravitational search algorithm (GSA) is required. In terms of the correlation coefficient for modelling slump flow diameter, L-box ratio, V-funnel duration, and compressive strength, the prediction results showed that MARS combined with GSA could improve the accuracy of the solo MARS model with 1.35%, 11.1%, 2.3%, as well as 1.07%. By contrast, Mp5-MT often demonstrates greater identification capability and more accurate prediction in comparison to MARS-GSA, and it may be regarded as an efficient approach to forecasting the rheological behaviors and compressive strength of SCC in infrastructure practice.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.6 s.165
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• pp.1055-1064
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• 1999

In this wort ER(electro-rheological) clutch and MR(magneto-rheological) clutch are devised and their performance characteristics such as response time and controllability are compared. As a first step, field-dependent yield stresses of ER and MR fluids are distilled in shear mode. For reasonable comparison between two clutches, a nondimensional design model is established by choosing same design parameters of gap size and number. Following the manufacturing of two clutches, field-dependent torque level, response time to step input, mechanical Power generation to electric power consumption are experimentally measured and compared. In addition, in order to investigate torque controllability of the clutches a sliding mode controller is formulated and experimentally realized. Control bandwidths of two clutches are identified and tracking control responses for desired torque trajectories are presented.

• Elastomers and Composites
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• v.47 no.3
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• pp.223-230
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• 2012

The rheological parameters of poly(methyl acrylate)-poly(acrylonitrile) copolymers were obtained by applying the experimental stress relaxation curves to the theoretical equation of the Eyring-Halsey non-Newtonian model. The experimentals of stress relaxation were carried out using the tensile tester with the solvent chamber. The determination of rheological parameters was performed from computer calculation. It was observed that the rheological parameters of these copolymer samples are directly related to the self diffusions and viscosities and activation energies of flow segments.

• Tribology and Lubricants
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• v.14 no.1
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• pp.85-93
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• 1998

The Bair & Winer's limiting shear stress rheological model is incorporated into the Reynolds equation to successfully predict the traction and film thickness for an isothermal line contact using the primary rheological properties. The modified WLF viscosity model and Barus viscosity model are also adapted for the realistic prediction of EHD tractional behavior. The influences of the limiting shear stress and slide-roll ratio on the pressure spike, film thickness, distribution of shear stress and nonlinear variation of traction are examined. A good agreement between the disc machine experiments and numerical traction prediction has been established. The film thickness due to non-Newtonian effects does not deviate significantly from the fdm thicknesss with Newtonian lubricant.

• 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.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.4
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• pp.769-777
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• 2015

In this study, the rheological models were introduced and developed to reflect rate dependent tensile behaviour of concrete. In general, mechanical properties(e.g. strength, elasticity, and fracture energy) of concrete are increased under high loading rates. The strength of concrete shows high rate dependency among its mechanical properties, and the tensile strength has higher rate dependency than the compressional strength. To simulate the rate dependency of concrete, original spring set of RBSN(Rigid-Body- Spring-Network) model was adjusted with viscous and friction units(e.g. dashpot and Coulomb friction component). Three types of models( 1) visco-elastic, 2) visco-plastic, and 3) visco-elasto- plastic damage models) are considered, and the constitutive relationships for the models are derived. For validation purpose, direct tensile test were simulated, and characteristics of the three different rheological models were compared with experimental stress-strain responses. Simulation result of the developed visco-elasto-plastic damage(VEPD) model demonstrated well describing and fitting with experimental results.

• Journal of the Korean Chemical Society
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• v.58 no.3
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• pp.251-257
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• 2014

The stress relaxation of poly(methyl acrylate)-poly(acrylonitrile) copolymer samples were carried out in air and distilled water at various temperatures using the tensile tester with the solvent chamber. The rheological parameters were obtained by applying the experimental stress relaxation curves to the theoretical equation of the Eyring-Halsey non-Newtonian model. The self diffusion, hole volume, viscosities, and thermodynamic parameters of copolymer samples were calculated from rheological parameters and crystallite size in order to study of flow segments in amorphous region. It was observed that the rheological parameters of these copolymer samples are directly related to the self diffusion, hole volume, viscosities, and thermodynamic parameters of flow segments.

• Journal of the Korean Geotechnical Society
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• v.27 no.10
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• pp.81-92
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• 2011

The rheological properties of Wyoming bentonites are strongly influenced by the size of particles, cation exchangeable capacity, arrangement and morphology of clay mineral. This paper presents the results of rheological investigations on the Wyoming bentonites aqueous dispersions: two types of particle flocculation were considered. For the Wyoming bentonite, 0g/L and 30g/L NaCl equivalent salinity were added in fresh and salt water to examine the rheological behavior. This paper examined the general rheological characteristics, compatibility of rheological models and correlation between soil structure and change in rheological properties of Wyoming bentonite caused by increasing salinity. From flow curves of bentonites hydrated with fresh water and salt water, the observed general flow behavior is very close to shear thinning with yield stress (or ideal Bingham fluid with yield stress and plastic viscosity). However, the change of shear stress at the same shear rate is clear, particularly for lower shear rate. Well-known rheological models are used to fit the data. There is a good agreement between rheological model and data: Carreau, Herschel-Bulkley and power-law for S=0g/L and bilinear, Herschel-Bulkley and power-law for S=30g/L. It may be due to the fact that the internal structural bonding (strong modification of particle-particle interactions from edge-to-edge and/or edge-to-face to face-to-face) in soil matrix is affected from the evolution of rheological properties with different salinities.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.316-322
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• 2002

This paper presents the temperature-dependent hysteresis identification of an electro-rheological (ER) fluid under various operating temperatures using the Preisach model. As a first step, polymethylaniline (PMA) particles are prepared and mixed with silicone oil to make an ER fluid. A couette type electroviscometer is then employed to obtain the field-dependent shear stress. In order to show the suitability of the Preisach model to predict a physical hysteresis phenomenon of the ER fluid, two significant properties; the minor loop property and the wiping-out property are experimentally examined under three dominant temperature conditions. Subsequently, the Preisach model fur the PMA-based ER fluid is identified using experimental first order descending (FOD) curves. The effectiveness of the identified hysteresis model is verified in the time domain by comparing the predicted field-dependent shear stress with the measured one under the both specified and unspecified temperatures. In addition, the hysteresis model proposed in this work is compared to Bingham model.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.8
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• pp.648-656
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• 2002

This paper presents the identification of temperature-dependent hysteresis of an electro-rheological (ER) fluid under various operating temperatures using the Preisach model. As a first step, polymethylaniline (PMA) particles are prepared and mixed with silicone oil to make an ER fluid. A couette type electroviscometer is then employed to obtain the field-dependent shear stress. In order to show the suitability of the Preisach model to predict a physical hysteresis phenomenon of the ER fluid, two significant properties; the minor loop property and the wiping-out property are experimentally examined under three dominant temperature conditions. Subsequently, the Preisach model for the PMA-based ER fluid is identified using experimental multiple first order descending (FOD) curves. The effectiveness of the identified hysteresis model is verified in the time domain by comparing the predicted field-dependent shear stress with the measured one under the both specified and unspecified temperatures. In addition, the hysteresis model proposed in this work is compared to Bingham model.