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.

Modeling of MR damper with hysteresis for adaptive vibration control

Abstract: This paper is concerned with structural vibration control using a semi-active magnetorheological (MR) damper. A simple mathematical model of MR damper is proposed to express its hysteresis effect of dynamic friction characteristics. The model can predict the damping force based on the inputs of velocity, internal state and input voltage to the MR damper. The model can also he used to obtain an inverse dynamic model to analytically determine the necessary input voltage so that the desirable damper force could be added to the structure in an adaptive manner. In conjunction with the LQG control which gives the desired target damping force, the total adaptive algorithm can work effectively even if the MR damper has uncertainty and changeability, which is validated in numerical simulations.

Seismic Control of Civil Structures Utilizing Semi–Active MR Braces

Abstract: This paper presents the feasibility and effectiveness of magnetorheological (MR) braces in earthquake hazard mitigation. In doing so, a nondimensional variable, β, which is the ratio of the yield force of the MR damper to forcing input (the product of a characteristic mass of the building and the seismic acceleration) is used to design the MR damper preventing the locked damper motion that may worsen seismic response of the building. From this theoretical analysis, the activation gap of the damper as an important design parameter to prevent the locked damper motion is chosen. Based on this analysis, the MR damper is fabricated by modifying the commercial MR damper of Lord Corporation, SD-1000-1. Then, a three-story building with MR braces is constructed and its dynamic equation is theoretically derived. In order to investigate semi-active control methods to MR braces, three different control algorithms are formulated and evaluated both numerically and experimentally. The results show that control of the building with semi-actively controlled MR braces is very effective.

Microstructure and magnetorheological properties of the thermoplastic magnetorheological elastomer composites containing modified carbonyl iron particles and poly(styrene-b-ethylene-ethylenepropylene-b-styrene) matrix

Abstract: Novel isotropic and anisotropic thermoplastic magnetorheological elastomers (MRE) were prepared by melt blending titanated coupling agent modified carbonyl iron (CI) particles with poly(styrene-b-ethylene-ethylene–propylene-b-styrene) (SEEPS) matrix in the absence and presence of a magnetic field, and the microstructure and magnetorheological properties of these SEEPS-based MRE were investigated in detail. The particle surface modification improves the dispersion of the particles in the matrix and remarkably softens the CI/SEEPS composites, thus significantly enhancing the MR effect and improving the processability of these SEEPS-based MRE. A microstructural model was proposed to describe the interfacial compatibility mechanism that occurred in the CI/SEEPS composites after titanate coupling agent modification, and validity of this model was also demonstrated through adsorption tests of unmodified and surface-modified CI particles.

Static yield stress of ferrofluid-based magnetorheological fluids

Abstract: In this work, the yield stress of ferrofluid-based magnetorheological fluids (F-MRF) was investigated. The fluids are composed of a ferrofluid as the liquid carrier and micro-sized iron particles as magnetic particles. The physical and magnetorheological properties of the F-MRF have been investigated and compared with a commercial mineral oil-based MR fluid. With the addition of a ferrofluid, the anti-sedimentation property of the commercial MR fluids could be significantly improved. The static yield stress of the F-MRF samples with four different weight fractions (ϕ) of micro-sized iron particles were measured using three different testing modes under various magnetic fields. The effects of weight fraction, magnetic strength, and test mode on the yielding stress have been systematically studied. Finally, a scaling relation, $\tau _{\rm ys} = {\rm a}B^{\rm b}$ , was proposed for the yield stress modeling of the F-MRF system.

Adaptive energy-absorbing materials using field-responsive fluid-impregnated cellular solids

Abstract: Adaptive materials with rapidly controllable and switchable energy-absorption and stiffness properties have a number of potential applications. We have developed, characterized and modeled a class of adaptive energy-absorbing systems consisting of nonlinear poroelastic composites wherein a field-responsive fluid, such as a magnetorheological fluid or a shear-thickening fluid, has been used to modulate the mechanical properties of a cellular solid. The mechanical properties and energy-absorbing capabilities of the composite are studied for variations in design parameters including imposed field strength, volume fraction of the field-responsive fluid within the composite and impact strain rates. The total energy absorbed by these materials can be modulated by a factor of 1- to 50-fold for small volume fractions of the fluid (∼15%) using moderate magnetic fields varying from 0 to 0.2 T. A scaling model is also proposed for the fluid–solid composite mechanical behavior that collapses experimental data onto a single master curve. The model allows optimization of the composite properties in tune with the application requirements. Potential application areas are discussed with emphasis on applicability in impact-absorbing headrests and cushioned assemblies for energy management. (Some figures in this article are in colour only in the electronic version)