This study aims to better understand the behavior of magnetorheological (MR) fluids operated in the non-conventional squeeze mode through the use of a custom designed rheometer. Squeeze mode is the least understood of the three operational modes of MR fluid and thus its potential has yet to be realized in practical applications. By identifying the behavior of MR fluid in this mode, the foundation for future development of MR technology will be laid.
Using the limited amount of literature available on squeeze-mode operation in conjunction with conventional principles associated with MR technology, a custom rheometer was designed and fabricated. A detailed account of the design considerations and background information on the fundamentals incorporated into the design are provided. The squeeze-mode rheometer was used to evaluate a variety of MR fluids to observe trends that may exist across fluids. Specifically, fluids of different ferrous particle volume fractions were considered.
Through testing, common trends in fluid stiffness were observed for multiple fluids tested with the squeeze-mode rheometer. When operated in squeeze mode, activated MR fluid has shown to provide substantial resistance to compressive loading, possibly making it attractive for low-displacement high-load systems. The primary observation from the tests is that the activated fluid’s stiffness progressively increases over the duration of fluid operation. This phenomenon is due to severe carrier-fluid separation coupled with the formation of ferrous particle aggregate clumps in the fluid. This effect is further explored in this research.
