Magnetorheological fluid

About: Magnetorheological fluid is a research topic. Over the lifetime, 8538 publications have been published within this topic receiving 131502 citations. The topic is also known as: MRF & MR fluid.

Nano-finishing of bio-titanium alloy to generate different surface morphologies by changing magnetorheological polishing fluid compositions

Abstract: Surface morphology i.e. surface roughness, surface texture, and surface wettability is a necessary requirement to lengthen implant’s life and also to increase its performance. The requirement of surface morphology of each implant varies depending upon its applications. In the present study, a nanofinishing process, Magnetic Field Assisted Finishing is used to generate different surface morphologies on the bio-titanium alloy. For this purpose, different magnetorheological fluids are synthesized by changing fluid composition to finish bio-titanium alloy using novel magnetic field assisted finishing tool. Further, the surface characteristics of the polished surfaces with different magnetorheological fluids are characterized for surface roughness, surface texture and to confirm their surface wettability (i.e. whether the surface is hydrophilic or hydrophobic). Ultrafine surface roughness (Ra = 10 nm) is achieved using magnetorheological fluid of Type - I having very smooth surface topography. While little bit rough surface (Ra = 70 nm) and less smooth surface topography is obtained using Type - II magnetorheological fluid. Experimentally it is observed that bio-titanium polished surface using magnetorheological fluid with Type - I polishing medium is hydrophilic in nature and it is better suited for semi-permanent type of implants and also for implants which engaged with relative motion in human body. While, magnetorheological fluid of type II should be selected to polish permanent implants which requires hydrophobic surface.

A review of advances in magnetorheological dampers: their design optimization and applications

Abstract: In recent years, magnetorheological (MR) fluid technology has received much attention and consequently has shown much improvement. Its adaptable nature has led to rapid growth in such varied engineering applications as the base isolation of civil structures, vehicle suspensions, and several bio-engineering mechanisms through its implementation in different MR fluid base devices, particularly in MR dampers. The MR damper is an advanced application of a semi-active device which performs effectively in vibration reduction due to its control ability in both on and off states. The MR damper has the capacity to generate a large damping force, with comparatively low power consumption, fast and flexible response, and simplicity of design. With reference to the huge demand for MR dampers, this paper reviews the advantages of these semi-active systems over passive and active systems, the versatile application of MR dampers, and the fabrication of the configurations of various MR dampers, and provides an overview of various MR damper models. To address the increasing adaptability of the MR dampers, their latest design optimization and advances are also presented. Because of the tremendous interest in self-powered and energy-saving technologies, a broad overview of the design of MR dampers for energy harvesting and their modeling is also incorporated in this paper.

Mitigation of biodynamic response to vibratory and blast-induced shock loads using magnetorheological seat suspensions

Abstract: The mitigation of biodynamic response to vibratory and blast-induced shock loads using a magnetorheological (MR) seat suspension is addressed in this study. To this end, an MR seat suspension model...

Yield stress measurements of magnetorheological fluids in tubes

Abstract: A pressure-driven apparatus was used to measure the yield stress of magnetorheological (MR) fluids as a function of the applied magnetic field, the carbonyl iron particle content, and the amount of surfactant used to stabilize the MR fluid. The yield stress was measured from the pressure difference necessary to initiate flow of a MR fluid in a straight tube present in a magnetic field. Yield stress measurements were made on MR fluids that contained up to 30 vol % carbonyl iron particles, up to 14 vol % surfactant oleic acid, and the remainder 100 cS silicone oil. In the absence of an applied magnetic field, the MR fluids did not have a yield stress and behaved as Newtonian fluids. In the presence of magnetic fields up to 2.2 kG, the MR fluids had yield stresses up to 1.9 kPa. An effect of the tube size on the yield stress was observed for MR fluids above 15 vol % carbonyl iron and magnetic fields above 1.0 kG.

Magnetorheological carbonyl iron particles doubly wrapped with polymer and carbon nanotube

Abstract: To improve magnetorheological (MR) characteristics of carbonyl iron (CI) microparticles, we introduce two-step CI coating procedures with poly(methyl methacrylate) (PMMA) and multiwalled carbon nanotube (MWNT) for the first time. Core(CI)-shell(PMMA) (CI-PM) structured composite magnetic microbeads were synthesized by dispersion polymerization first, showing improved dispersion stability and sedimentation quality. However, its magnetic strength was decreased compared with that of pristine CI-based MR fluid. To enhance its magnetic strength, the core-shell type CI-PM particles were wrapped with MWNT via ultrasonication. Rheological properties of their MR fluid were measured by a rotational rheometer with a magnetic field supplier. The CI-PMMA-MWNT (CI-PM-NT) particles were found to show better flow and dynamic rheological properties compared to those from CI-PM particles while density of the CI-PM-NT particles was not much different from that of CI-PM, implying that sedimentation stability of the CI-PM-NT ...