In this paper the magnetomechanical properties of magnetorheological (MR) elastomers with isotropic and anisotropic structure are examined. A method for manufacturing magnetorheological elastomers (MRE) with thermoplastic elastomer matrix and 60 μm iron particles is presented. The influence of various chemical compositions on the material parameters is investigated. The properties of isotropic and anisotropic MR elastomers are examined in a wide range of mechanical and magnetic stimulations. Test samples are subjected to cyclic shearing with a constant frequency of 1 Hz. The change in magnetomechanical properties is expressed by the relative change of hysteresis loop area δW and stress amplitude δτ .
This paper presents a procedure for manufacturing composites, a methodology for testing them and the cyclic properties of isotropic magnetorheological elastomers. The choice of a thermoplastic matrix and magnetically active iron powder as the filling (much larger than the carbonyl iron powder filling used so far) is expounded. A manufacturing technology has been developed. Possibilities for the experimental investigation of magnetomechanical properties have been created by building a measuring system enabling the testing of various elastomers in a wide range of mechanical and magnetic parameters. The effect of the magnetic field and that of the stress frequency on the damping properties of a selected elastomer (considered to be optimal) were examined.
In this two-part research project the inelastic properties of a selected group of
magnetorheological composites under cyclic shear have been identified. Composites whose
matrices were elastic porous structures with pores filled with a magnetorheological
fluid were investigated. The composite materials’ functional properties are similar
to those of magnetorheological fluids. But, as opposed to the fluid alone, the
composite’s geometry and dimensions can be freely shaped. Owing to this, the
costs can be reduced and the applicability can be extended. In the literature
on the subject such composites are also referred to as magnetorheological fluid
impregnated solids. In the first part of this work an overview of smart magnetic
materials is presented. Then the originally fabricated composite, consisting of
a matrix and a filling fluid, is described. The test stand, including a system of control,
acquisition and processing of measuring (mechanical and magnetic) signals, is
presented. The experimentally determined hysteresis loops for cyclic shear are
used in the second part of this research project to identify constitutive models.
Corrosion is constantly a major problem of the world economy in the field of metal products, metal processing and other areas that utilise metals. Previously used compounds utilizing hexavalent chromium were amongst the most effective materials for corrosion protection but regulations have been recently introduced that forbid their use. Consequently, there is a huge drive by engineers, technologists and scientists from different disciplines focused on searching a new, more effective and environmentally-friendly means of corrosion protection. One novel group of materials with the potential to solve metal protection problems are sol-gel thin films, which are increasingly interesting as mitigation corrosion barriers. These environmentally-friendly and easy-to-obtain coatings have the promise to be an effective alternative to hexavalent chromium compounds using for anti-corrosion industrial coatings. In this review the authors present a range of different solutions for slow down the corrosion processes of metallic substrates by using the oxides and doped oxides obtained by the sol-gel method. Examples of techniques used to the sol-gel coating examinations, in terms of anti-corrosion protection, are also presented.
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