A seismic magneto-rheological (MR) fluid by-pass damper

This study focuses on the design, development and testing of a magneto-rheological (MR) fluid by-pass damper for large-scale semi-active seismic applications. Two kinds of MR bypass valves are designed and manufactured. One is the MR valve in annular flow configuration; another is a modular MR valve in radial flow configuration. Theoretical analysis is performed on both valves using fluid mechanics and three dimensional electromagnetic finite element analyses is performed.; The performance of the MR fluid valves is characterized by means of quasi-static characterization. Dynamic tests are conducted on the modular MR fluid by-pass valve at Enidine Corporation. A new MR fluid is also developed for the MRF by-pass valve application. The MR fluid has a low off state viscosity and high field-dependent yield strength. The rheological behavior of the MR fluid is examined. The theoretical predictions are compared to the experimental results. Comparing with the annular flow MR fluid valve, the new MR fluid valve with radial flow configuration is more compact, efficient and flexible in design. Both experimental and theoretical results show that the MR fluid valves can generate a considerable dynamic force range, which meets the large force requirements for seismic applications.; The dynamic properties of the modular MR fluid by-pass damper are evaluated at Enidine Corporation. The results obtained, indicated that the MR fluid damper is capable of generating high controllable force suitable for seismic applications.