Electrorheological fluids

Magnetorheological materials (fluids) are the magnetic equivalent of electrorheological fluids. In this case, the particles are either ferromagnetic or ferrimagnetic sohds that are either dispersed or suspended within a Hquid and the apphed field is magnetic (14). 

Electrorheological Fluids. Electrorheological fluids are a newer category of hydrauhc fluids being actively pursued for use in shock absorbers. An electric field causes the fluid to thicken. 

A] As a result of applying a magnetic field, the poles of tiny magnetic particles in a magnetostrictive material line up, which alters the shape of the material. [B] The application of an electric field aligns particles in an electrorheological fluid. 

A type of material known as shape memory alloy (SMA) can perform this trick. SMAs are more complicated than electrorheological fluids and the other smart materials previously described in this chapter. An SMA does not only react or respond to environmental conditions, it also has a memory that enables it to return to a specific structure, or sometimes switch between two different structures. After the material has been set, it can recover from a deformation that would be permanent in other materials. When the temperature is raised by an amount that depends on the specific material, it snaps back into shape automatically. The memory is based on phase transitions, as described in the sidebar on page 120. 

Willis M. Winslow, an engineer and inventor, files a U.S. patent that includes the first description of an electrorheological fluid. 

Particles immersed in a fluid with a different dielectric constant or conductivity (electrorheological fluid) assembled into chains, columns of chains, and glasses in the presence of an electric field Electric dipole interactions nm to (Jim 55... 

Their unique properties predestine them for both very specific applications and broad use in the field of polymer composites. They not only enhance mechanical properties but also electrical and thermal properties, act as flame retardants, etc. Thus their positives can be successfully exploited from simple or advanced polymer matrix reinforcement, through electronic devices, sensors and actuators, to electrorheological fluids, to name just the most important applications. 

Chin B. D. and Park O. O., Rheology and microstructures of electrorheological fluids containing both dispersed particles and liquid drops in a continuous phase. J. Rheol 44 (2000) PP. 397-412. 

Fig. 8-1). If one attempts to slide one electrode relative to the other the particle chains resist with a force that increases roughly as (Winslow 1949 Klingenberg and Zukoski 1990). Electrorheological fluids were discovered and patented by W. M. Winslow (1947, 1949) some 50 years ago. Since then, Winslow and others have dreamed of widespread applications of these fluids in fast clutches, actively controlled shock absorbers, variable-flow pumps, and robotic activators.

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