• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.9
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• pp.679-687
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• 2003

Shock wave reduction in electrorheological(ER) smart structures is studied. ER insert is a composite structure comprising two elastic outer layers between which is sandwiched layer of ER fluid. When a voltage is applied across the outer layers. the shear modulus and the loss factor of the ER fluid are enabled, and thus the dynamic properties of the composite structure is altered. For the shock wave reduction in a hull mount of a submerged structure, ER inserts are made on the hull mount structure. To investigate the ER insert shape. many types of ER insert pattern are considered. Modal test of ER insert structures is performed to obtain the mode shapes, natural frequencies and the acceleration transmissibility. The acceleration transmissibility is reduced at such a frequency region when an electric field is applied. It is observed that the natural frequencies and mode shapes can be tunable by applying electric field. The ER-inserted hull mount is installed in an integrated system and the overall performance of shock wave reduction is tested. The possibility of shock wave reduction in the hull mount is demonstrated.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.1
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• pp.134-141
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• 1993

Electro-Rheological(ER) fluids undergo a phase-change when subjected to an external electic field, and this phase-change typically manifests itself as a many-order-of-magnitude change in the rheological behavior. This phenomenon permits the global stiffness and energy- dissipation properties of the beam structures to be tuned in order to synthesize the desired vibration characteristics. This paper reports on a proof-of-concept experimental investigation focussed on evaluation the vibration properties of hollow cantilevered beams filled with an ER fluid. and consequently deriving an empirical model for predicting field-dependent vibration characteristics. A hydrous-based ER fluid consisting of corn starch and silicone oil is employed. The beams are considered to be uniform viscoelastic materials and modelled as a viscously-damped harmonic oscillator. Natural frequency, damping ratio and elastic modulus are evaluated with respect to the electric field and compared among three different beams: two types of different volume fraction of ER fluid and one type of different particle concentration of ER fluid by weight. Transient and forced vibration responses are examined in time domain to demonstrate the validity of the proposed empirical model and to evaluate the feasibility of using the ERfluid as an actuator in a closed-loop control system.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.4
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• pp.296-301
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• 2001

Electro-Rheological (ER) fluids belong to a class of colloidal suspensions whose global characteristics can be controlled by the imposition of an appropriate external electrical field upon the fluid domain. The ER fluids for smart hydraulic system are a class of colloidal dispersion which exhibit large reversible changes in their rheological behavior when subjected to external electrical fields. This paper presents experimental results on mechanical properties of an ER fluids subjected to electrical fatigues. As a first step, ER fluid is made of methyl cellulose(MC) ingredient choosing 25% of particle weight-concentration. Following the construction of test for mechanical properties of ER fluid, the shear stress, dynamic yield stress and current density of the ER fluids are experimentally distilled as a function of electric field cycles. The mechanical properties test of operated ER fluids are distilled and compared with those of unused ER fluids.

• KSTLE International Journal
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• v.2 no.2
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• pp.142-145
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• 2001

The electrorheology of the chitosan adipnate suspension in silicone oil was investigated. Chitosan adipnate suspension showed a typical ER response (Bingham flow behavior) upon application of an electric field. The shear stress for the chitosan adipnate suspension exhibited a linear dependence on the volume fraction of particles and an electric field power of 1.88. The experimental results for the chitosan adipnate suspension correlated with the conduction models and this suspension was found to be an anhydrous ER fluid.

• KSTLE International Journal
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• v.7 no.1
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• pp.18-21
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• 2006

The electrorheology of hollow PANI derivative suspensions in silicone oil was investigated by varying the electric fields and shear rates, respectively. The hollow PANI derivative susepnsions showed a typical electrorheological (ER) response caused by the polarizability of an amide polar group and shear yield stress due to the formation of chains upon application of an electric field. The shear stress for the hollow PANI succinate suspension exhibited an electric field power of 0.67. On the basis of the experimental results, the newly synthesized hollow PANI derivative suspensions were found to be an anhydrous ER fluid.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.4
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• pp.148-157
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• 1994

A multi-cylindrical hydraulic valve incorporating with an electro-rheological(ER) fluid is developed in this study. Field-dependent Bingham properties of the ER fluid are exploited to devise the valve system which features fast system response as well as simple mechanism. The fast response is accrued from almost instant response characteristics of the ER fluid itself, and the mechanism configuration is simplified since no nechanically moving parts are required. The material properties of the ER fluids to be utilized for modeling of the proposed valve system are firstly tested with a couette-type electroviscometer. The design and manufacturing processes are then undertaken on the basis of model parameters. The performance characteristics of the valve system are evaluated in terms of pressure variations with respect to the intensity of employed electric fields and flow rates.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.2
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• pp.30-37
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• 2006

The purpose of this study is to visualize the characteristics of ER fluids as preceding step of developing 3 port ER valves. ER fluids are made with silicone oil and 3 weight fraction starch having hydrous particles. The flow visualization of ER fluids flow is obtained by CCD camera with changing the strength of electric field to ER fluids flow. As the strength of the electric field increases, more clusters in flow are made and these clusters are though to be the reasons of the load flow rate being increased and the outlet flow rate being decreased. The ER Valves and load and outlet flow rate check method are considered to be applied to the fluid power control system.

• KSTLE International Journal
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• v.2 no.1
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• pp.71-74
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• 2001

The electrorheological(ER) performance of a chitosan sebaciate suspension in silicone oil was investigated by varying the electric fields, volume fractions of particles, and shear rates, respectively. The chitosan sebacicate susepnsion showed a typical ER response caused by the polarizability of an amide polar group and shear yield stress due to the formation of multiple chains upon application of an electric field. The shear stress for the suspension exhibited a linear dependence on the volume fraction of particles and an electric field power of 1.88. On the basis of the results, the newly synthesized chitosan sebacicate suspension was found to be an anhydrous ER fluid.

• Tribology and Lubricants
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• v.25 no.3
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• pp.176-181
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• 2009

Aminated polyacrylonitrile as the new organic disperse phases of the anhydrous ER fluid has been synthesized and ER effect of the suspension composed of aminated polyacrylonitrile in silicone oil investigated. The 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 1.6 power on theelectric field. The current density and the conductivity of the of aminated polyacrylonitrile suspension increase with the electric field intensity and moreover the conductivity of the suspension is about 8 order of magnitude higher than that of the silicone oil. On the basis of the the results, aminated polyacrylonitrile suspension showed the ER flow behavior upon application of the electric field due to the polarizability of the branched amine polar group of the aminated polyacrylonitrile particles.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.213-216
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• 2005

This paper presents force feedback control performance of a 3DOF haptic device that can be used for minimally invasive surgery (MIS). As a first step, a 3DOF electrorheological (ER) joint is designed using a spherical mechanism. And it is optimized based on the mathematical torque modeling. Subsequently, the master haptic device is manufactured by the spherical joint. In order to achieve desired force trajectories, model based compensation strategy is adopted for the ER master. Therefore, Preisach model fur the PMA-based ER fluid is identified using experimental first order descending (FOD) curves. A compensation strategy is then formulated through the model inversion to achieve desired force at the ER master. Tracking control performances for sinusoidal force trajectory are presented, and their tracking errors are evaluated.