Study of the Behavior of MR Fluids in Squeeze, Torsional and Valve Modes

Abstract

In order to understand the effectiveness of MR fluids in some applications, such as bearings, this work focuses on the properties of MR fluids under squeeze mode, torsional mode and squeeze combined with torsional mode. A special device was designed and fabricated to perform these experiments, which were carried out on an Instron Multiaxial Testing Machine. The hysteresis loops of the MR fluids were studied for different intensities of electric current, frequency, strain amplitude and angle amplitude. The results showed that the damping force and the area of the hysteresis loop of MR fluids increase with the current and strain amplitude. Changes on the frequency did not influence the stress values significantly, within the range of frequencies used in these experiments. In order to evaluate the performance of a squeeze film damper (SFD), measurements were made using a MR damper manufactured by Lord Corporation (RD1005), which operates in valve mode. The results of the SFD were compared to the ones obtained with the RD1005 damper. The shape of the hysteresis loop curves and the MR effect were found to be different for the squeeze film damper and the RD1005 damper.

Compressive and tensile stresses of magnetorheological fluids in squeeze mode

“…Kulkarni et al [16] have obtained similar results from the dynamic loadings of a hydrocarbon-based MR fluid under squeeze mode. They found less effect of the tensile stresses under various applied currents as compared to the compressive stresses.…”

Squeeze flow behaviors of magnetorheological plastomers under constant volume

“…The compressive and tensile behaviors of MRP that we have discussed above reflect the quasistatic mechanical performance. The dynamic mechanical behavior is another important aspect to assess the performance of MRP for academia as well as for some potential applications [Farjoud et al (2009); Farjoud et al (2011); Kulkarni et al (2003)]. Oscillatory shear mode is the mostly used dynamic characterization method to investigate the rheological properties of MR fluids [de Vicente et al (2011b)], while the oscillatory squeeze behaviors of MR fluids are paid less attention though it is also valuable to understand the MR mechanism.…”

“…In addition, there seems no report about the investigation on the oscillatory squeeze behavior of MR fluids. Some preliminary applications by using MR fluids working under squeeze mode in damper [Ahn et al (2004); Carmignani et al (2006); Kulkarni et al (2003); Wang et al (2005)] and mount [Farjoud et al (2011)] have been tried; superior performance was presented in these squeeze-film dampers than that of the devices working under shear mode.…”

Understanding the super-strong behavior of magnetorheological fluid in simultaneous squeeze-shear with the Péclet number

“…This squeezestrengthening phenomenon, also known as the superstrong effect (Tao, 2001), could drastically increase the torque-to-weight ratio of MRF devices, but has not yet been used in practical applications due to limited understanding and predictability of the phenomenon. Moreover, its feasibility in rotary (shear-type) devices is questionable, as it has been demonstrated that superimposing squeeze motion to a shearing flow does not always result in an increase in MRF yield stress (Kulkarni et al, 2003). To our knowledge, the only recorded design attempt of a super-strong device is an MRF brake, which uses a double magnetic circuit to compress the MRF during shear motion (Sarkar and Hirani, 2013).…”