The basic operational principle is the adjustment of the flow path by means of the motion of a mechanical part, e. In contrast, electrorheological fluids ERF allow to directly influence their rheological properties i.
This, in turn, allows to change the volume flow in a hydraulic circuit without any mechanical motion. Since the electrorheological effect is very fast in the range of a few milliseconds , ERF can be utilized to build very fast hydraulic actuators. Furthermore, the resulting construction is kept very simple since there are no complicated mechanically moving parts.
In this research project, several applications in the field of valve constructions, linear actuators and automotive suspension systems, and shock absorbers in maritime applications were considered.
Original Research ARTICLE
The basis for all results was a detailed mathematical modeling of the ERF by means of a continuum mechanical model, which describes the stress as a function of the electric field strength and the shear rate. The characteristics of the shear stress as a function of shear rate is depicted in Fig.
Shear stress as a function of the shear rate for a typical ERF.
The core part of most electrorheological components is an ER valve, which basically features two parallel electrodes, where the ERF is flowing in between, see Fig. By applying an electric voltage to the electrodes, the flow resistance of the valve can be increased.
- Applications of electro-rheological fluids in vibration control: a survey.
- The Sustainability Handbook: The Complete Management Guide to Achieving Social, Economic and Environmental Responsibility.
- Electrorheological fluids: structures and mechanisms - Soft Matter (RSC Publishing)!
- Donate to arXiv.
- Brain CT Scans in Clinical Practice?
If the electric voltage is chosen large enough, the valve can be even closed completely. The dynamics of this change of the flow of the ERF is, as already mentioned, very fast. Change of the fluid velocity in an ER valve for changes in voltage and the pressure, respectively. Adjustable dampers are utilized in semi-active suspension systems to obtain a good trade-off between driving comfort and driving stability.
This can be obtained by adjusting the damping according to the actual road conditions.
In this research cooperation, mathematical models and control strategies for vehicles equipped with this semi-active suspension systems were derived. It could be shown by means of test drives that a significant improvement of driving comfort and stability can be obtained in comparison to a vehicle, which utilize a classical passive suspension system. The possibility to directly influence the characteristics of an ERF by means of an electric field enables to control the flow of ERFs by means of a suitable shaping of the electrodes.
A possible application are digital electrorheological valves, which were developed in a further cooperation with Fludicon. The basic idea is to change the flow resistance by means of switching on and off a number of serially connected ER valves. This allows to utilize cheap high voltage power supplies with constant voltage. Utilizing e.
Electrorheological Fluids - Hao - - Advanced Materials - Wiley Online Library
Sign In. Access provided by: anon Sign Out.
- Electrorheological fluids: smart soft matter and characteristics.
- Search form?
- Electrorheological fluid.
- The Transcervical Approach in Thoracic Surgery;
- The nature of fasting.
Dielectric response of electrorheological fluids: Application to the electrical characterization of particles suspended in liquid medium Abstract: Electrorheological ER fluids are suspensions of fine particles dispersed in a dielectric liquid. Upon application of an electric field, the solid phase particles fibrillates along the field lines between the electrodes. Thus, the rheological properties of the suspension are drastically modified strongly dependence of the viscosity of the suspension on the applied field strength. To understand and model the ER phenomenon, it is necessary to take into account the dielectric properties conductivity and permittivity of the solid and liquid phases.