A novel method for measurement of MR fluid sedimentation and its experimental verification

This article presents a novel sedimentation measurement technique based on quantifying the changes in magnetic flux density when the magnetorheological fluid (MRF) passes through the air gap of the magnetic circuit. The sedimented MRF appears to have as a result of increased iron content. Accordingly, the sedimented portion of the sample displays a higher magnetic conductivity than the unsedimented area that contains less iron particles. The data analysis and evaluation methodology is elaborated along with an example set of measurements, which are compared against the visual observations and available data in the literature. Experiments indicate that unlike the existing methods, the new technique is able to accurately generate the complete curves of the sedimentation profile in a long-term sedimentation. The proposed method is capable of successfully detecting the area with the tightest particle configuration near the bottom ('cake' layer). It also addresses the issues with the development of an unclear boundary between the carrier fluid and the sediment (mudline) during an accelerated sedimentation process; improves the sensitivity of the sedimentation detection and accurately measure the changes in particle concentration with a high resolution. (technical note)