Wear and Friction Characteristics of Magnetorheological Fluid under Magnetic Field Activation

In this article, wear and friction characteristics of a magnetorheological (MR) fluid were studied under different magnetic fields. Using a pin-on-disc tribometer, the wear loss and friction coefficient were obtained with and without a magnetic field. The friction and wear of three typical materials under magnetic field were investigated at various normal loads and rotating speeds. After the wear tests, the worn surfaces of specimens were observed using a scanning electron microscope (SEM) in order to investigate the wear mechanisms, and the contacting surfaces were analyzed by energy-dispersive X-ray spectroscopy (EDS) to investigate the variation of elemental composition on the worn surface. Test results showed that the MR fluid exhibits better tribological characteristics under a magnetic field compared to the case without a magnetic field. The general morphology of the MR particles and wear debris was observed to assist with the analysis of friction and wear. The SEM micrographs and EDS spectra of the worn surfaces showed that the predominant wear mechanism in the case of the steel and brass specimens was abrasive wear by asperities and MR particles on the worn surfaces, whereas a mixed wear mechanism that included adhesive wear and abrasive wear was observed in the case of the aluminum specimen.     

Study of Thin Fluid Film Using Impulsive Load and Its Optimization for Noise Reduction in Forging

To reduce the transmission of impact energy in a drop forge from the impacting die to the anvil while retaining the deformation efficiency, a double-pad oil film has been developed and tested.

The present paper is focused on the behavior of the oil film under an impulsive load. From the experimental apparatus, the measured pressure distribution over the bottom pad area is compared with that of theoretical results for both small and large gaps.

On the basis of the theoretical analysis of the effect of the bearing parameters on the deformation efficiency and emitted sound pressure, the present double-pad oil film bearing is optimized experimentally. From the recorded signals, it is shown that an optimum point does exist where the emitted sound pressure is minimum.