Study on the conformational behaviour of magnetorheological fluid in squeeze mode

Abstract

This study intends to address the lack of awareness regarding magnetorheological (MR) fluids behaviour in squeeze mode. The aim of this study is to provide a thorough investigation of the microstructure of MR fluid under compression. The explanation to the numerous commercial applications of MR fluids lies in their reversible rheological transition in which is thoroughly linked to the drastic transformation in suspension microstructures. The success of MR fluid is apparent in many disciplines, ranging from the automotive and civil engineering communities to the biomedical engineering community. MR fluids operated in squeeze mode have unique features as a result of its ability to produce much higher compressive and tensile stresses. This research has identified the compression behaviour of MR fluids under squeeze mode. The compression behaviour of the epoxy-based MR fluid was examined throughout compression tests of 25%, 50% and 75%. The compressive stress recorded under compression of 75% was significantly higher than under compression of 50%. Meanwhile, under compression of 25%, the compressive stress showed only a slight increased in comparison. In addition, the compressive stresses plotted by 20% volume fraction of carbonyl iron particle (CIP) were always higher than 10% volume fraction of CIP. Therefore, the higher the volume fraction of CIP and the compressive strain, the higher compressive stress of MR fluids would be achieved. During compression, the volume fractions of CIP of the MR fluids have shown an increase as a result of relative decrease in the volume of samples composition. In the microstructure analysis, the particles distributions and column sizes of the specimens were found to increase in conjunction with the compression and recorded a significant value under compression of 75%. This microstructure study proves that during the compression, most of the CIP were hold in the fluids while the epoxy was expelled out of the compression area.