Characteristics of Magnetorheological Fluids Applied to Prosthesis for Lower Limbs

Magnetorheological Fluids (MRF) are a new type of intelligent materials whose rheological characteristics can change with a magnetic field that can be controlled, it experiments significant reversible changes in their mechanical properties, especially their viscosity. When applying a magnetic field transverse to the flow, the system stops being Newtonian and acquires viscoelastic characteristics, although it is common for dispersions of any type to form structures to facilitate sedimentation, in Magnetorheological (MR) fluids uniform distribution of structures is maintained while the magnetic field is present. It depends of the application that is used for, some of this device that are based on the fluid can be dampers, brakes and clutches, etc., have been successfully introduced in engineering applications and prosthetics devices. Some prosthetics for lower limbs are most rigid and does not provide the suitable damping on the walking generating problems such as scoliosis and hip damage, in order to avoid several human damages; this paper propose a prosthetic for lower limbs using MRF whose mechanical properties allows a complete damping control on the walking. Magnetorheological technology allows an instant response so that users do not have to wait for the prosthesis to respond. MRF damper is characterized according to the requirements of the design, using a system equipped with a hydraulic press to analyze the behavior of the fluid in different states that will change according to the variable magnetic field.