Most of the commercially available magnetorheological (MR) fluids are only tested up to 1200 1/s shear rates but with no magnetic field. Data are rarely available at high shear rates with magnetic field applied. In most of the applications where MR fluids are used, such as MR rotary brakes or MR translational dampers, the shear rates can be in the order of thousands and in some applications, the shear rates could be in the order of ten thousands (1/s) and higher. At these high shear rates, most MR fluids will be shear thinning and Bingham model will be inappropriate to use. The focus of this study is on the mathematical modeling of a drum-type MR rotary brake using the Herschel-Bulkey model.

The effect of hybrid control technique on transient dynamics of semiactive vehicle suspensions is studied analytically, using a quarter-car model. Hybrid semiactive control refers to a technique that mathematically combines the commonly used skyhook and groundhook control methods. The transient analysis includes an evaluation of the effect of hybrid control on different aspects of the suspension dynamics, vehicle body response, and axle dynamics, due to a step input at the wheel. The damper force–velocity trajectories, vehicle body and axle response, and vehicle body jerk are among the metrics that are examined as part of this analysis. The results of the study show that several tradeoffs exist between the transient response of the vehicle body and the axle. The tradeoffs can be adjusted through changing the hybrid control gain, which shifts the emphasis on skyhook and groundhook controls. The results further indicate that, in balance, hybrid control can be more effective in controlling suspension dynamics than either skyhook or groundhook control.

Oil flowlines, the first “pipeline” system connected to the wellhead, are pipelines that are 5 to 30.5 cm (two to twelve inches) in diameter, most susceptible to corrosion, and very difficult to inspect. Herein, an external corrosion detection sensor for oil and gas pipelines, consisting of a semicircular plastic strip, a flat dog-bone-shaped sacrificial metal plate made out of the same pipeline material, and an optical fiber with Fiber Bragg Grating (FBG) sensors, is described. In the actual application, multiple FBG optical fibers are attached to an oil and gas pipeline using straps or strips or very large hose clamps, and, every few meters, our proposed corrosion detection sensor will be glued to the FBG sensors. When the plastic parts are attached to the sacrificial metals, the plastic parts will be deformed and stressed; thus, placing the FBG sensors in tension. When corrosion is severe at any given pipeline location, the sacrificial metal at that location will corrode till failure and the tension strain is relieved at that FBG Sensor location, and therefore, a signal is detected at the interrogator. Herein, the external corrosion detection sensor and its design equations are described, and experimental results, verifying our theory, are presented.