Both the scientific and relevant industrial sectors have felt the need for devices that can help understand the characteristics of smart fluids. To address this demand, scientists from IIT Patna prepared Nano iron powder-based MR fluids and developed a hybrid magneto-rheometer. This device can trace the rheological (flow and deformation) and tribological behaviour (friction and wear) of the MR fluid in the non-conventional compression and shear mode both with and without a magnetic field, using the custom-designed rheometer.
The newly designed innovative hybrid magneto-rheometer offers a novel way to characterize the performance of smart fluids that are useful for medicine, aerospace, the defense sector and automation. These fluids increase in viscosity when subjected to a magnetic field. MR fluids are “smart” materials that rapidly change their mechanical properties when exposed to a magnetic field, increasing in apparent viscosity, to the point of becoming a viscoelastic solid. The fluid can transmit force which can be controlled with an electromagnet, giving rise to many possible control-based applications.
This unique capability makes them ideal for adaptive technologies such as brakes, clutches, shock absorbers, vibration control systems, dampers, actuators, and medical devices. The increasing need to accurately understand how these fluids behave under actual operating conditions has remained a significant challenge. Particularly, the compression plus shear mode is the least understood of the MR fluid’s operation modes, limiting the potential of its practical applications.
This initiative is led by Prof Chiranjit Sarkar, with support from the Nano and Advanced Materials division of the Department of Science and Technology (DST). The team fabricated a rheometer that can measure both the rheological and tribological properties of an MR fluid under compression and shear modes of operation at different normal loads, both with and without a magnetic field.
In the hybrid rheometer, the scientists generated a constant, high-magnitude magnetic field throughout the MR sample region using a smaller current. They conducted experiments in compression plus shear mode (mixed mode) for iron-based MR fluid. This development demonstrates how advances in testing technology can drive innovation in smart materials, providing researchers and industry with the tools needed to engineer high-performance MR fluids for future generations of adaptive and energy-efficient technologies.
The comprehensive testing capability of the prototype they developed provided a better understanding MR fluid performance than conventional characterization methods. Such hybrid Rheometers can help understand the viscoelastic properties of materials that are indispensable in sectors such as polymers, pharmaceuticals, food processing, cosmetics, and petrochemicals.
