Monitoring sedimentation of magnetorheological fluids using an infrared night vision wide-angle lens visual monitoring system with dynamic calibration method

Abstract

Magnetorheological fluids (MRFs) have demonstrated remarkable potential in engineering vibration damping. Nonetheless, the substantial density difference between the dispersed phase and the dispersing medium causes inevitable sedimentation in MRFs, significantly affecting the material’s service life and restricting its engineering applications. Monitoring technology for MRF sedimentation plays a crucial role in comprehending sedimentation behavior and holds significant importance for the subsequent redispersion of MRFs. Consequently, the monitoring technology for MRFs has been gaining increasing attention in recent times. This study proposes a machine vision-based real-time and in situ monitoring method to test and evaluate the suspension stability of MRFs. Firstly, an infrared wide-angle night vision lens (IWNVL) is fixed at the side of a MRF column for capturing the sequential MRF images during its sediment process. Then, the gray values (GVs) could be obtained by utilizing Gaussian filtering and morphological filtering. Secondly, by combining the Kynch sedimentation theory and Lambert-Beer composite material optical transmission theory, an analytic model is established in this works to find the relationship between the MRFs’ concentration gradient to its GVs. In what follows, the concentration distribution varied with time could be tested by the GVs of the sequential MRF images. Finally, a sentimental experiment for prepared MRF column is carried out in this works, and the testing results are verified and discussed by a capacitance sensor and a simple visual observation. The experimental results demonstrate that the proposed method could accurately measure the concentration distribution during MRFs’ sedimentation process under different initial light intensities.