Papers by Author: Izwan Ismail

Abstract: This paper presents the effects of magnetorheological (MR) fluid parameters, bidisperse ratio, carrier fluid viscosity and particle volume fraction, on its mechanical behaviour using statistical investigation. Silicone oil-based MR fluid samples were compressed using universal testing machine (UTM) in a vertical direction. A set of eight experiments was designed by Design Expert 7 software in which was conducted at two levels for each factor. Stress-strain curves that obtained from the compression test were then analysed by testXpert analyser software. The responses in terms of maximum stresses at 0.75 of strain were extracted from the curves. The result indicated that a combination of high bidisperse ratio and particle volume fraction, and a low carrier fluid viscosity could produce a high compressive stress. The findings are important to be considered in designing squeeze mode MR fluid actuators.

Abstract: In this paper, effects of critical parameters, namely initial gap, squeezing speed and applied current were statistically investigated on the mechanical behaviour of MR fluid in squeeze mode. A set of 17 experiments was designed using Design Expert 7 software to gather data from response surface methodology (RSM). The responses in terms of compression modulus were then calculated. An MRF132-DG was used as a sample in each experiment. The experiments were conducted under compression stress mode using universal testing machine (UTM). Stress-strain curves were analysed using the machine integrated TestXpert analyser software package. The stress-strain curves of MR fluid under squeeze have produced a shear thickening behaviour at 13.54 MPa of the highest stress at 0.75 of strain. A correlation between the three parameters and the stress-strain properties was specified. The results showed that the initial gap and supplied current were significantly produced a high compression modulus for the MR materials. These findings are important to enhance the capability of the squeeze MR devices to operate at its best performance. High compressive stress is crucial for most magnetorheological (MR) materials, particularly in squeeze mode devices.

Abstract: In our earlier work, test equipment has been designed, simulated and fabricated to perform experiment on MR fluids in squeeze mode. Preliminary results were gathered and presented for the purpose of validating the test equipment. Therefore, in this paper, a further systematic investigation of MR fluids in squeeze mode has been carried out. As a result, MR fluids experienced rheological changes in three stages during compression and tension. Fluid-particles separation phenomenon was the main caused for the unique behaviour of MR fluids. Particle chains depended on the structure transformation in which the carrier fluid movement can be controlled by changing the magnetic field strength.

Abstract: In this study, a testing rig in squeeze was designed and developed with the ability to conduct various tests especially for quasi-static squeezing at different values of magnetic field strength. Finite Element Method Magnetics (FEMM) was utilized to simulate the magnetic field distribution and magnetic flux lines generation from electromagnetic coil to the testing rig. Tests were conducted with two types of MR fluid. MRF-132DG was used to obtain the behaviour of MR fluid, while synthesized epoxy-based MR fluid was used for investigating the magnetic field distribution with regards to particle chains arrangement. Simulation results of the rig design showed that the magnetic flux density was well distributed across the tested materials. Magnetic flux lines were aligned with force direction to perform squeeze tests. Preliminary experimental results showed that stress-strain pattern of MR fluids were in agreement with previous results. The epoxy-based MR samples produced excellent metallographic samples for carbonyl iron particles distributions and particle chain structures investigation.