Master of Engineering - Research
Faculty of Engineering
Tian, Tongfei, Study of magnetorheology and sensing capabilities of graphite based MR elastomers, Master of Engineering - Research thesis, Faculty of Engineering, University of Wollongong, 2011. http://ro.uow.edu.au/theses/3320
This study focuses on the magnetorheology and sensing capabilities of graphite based MR Elastomers (Gr MREs). By introducing graphite to conventional MREs, the Gr MREs with various graphite weight fraction are derived.
Both steady state tests and dynamic tests such as strain amplitude sweep and angular frequency sweep were used to test the magnetorheology of Gr MREs. With the help of graphite in MREs, the storage and loss moduli are both changed. The samples with higher graphite weight fraction show higher initial storage and loss moduli and lower MR effects.
Also the microstructures of isotropic and anisotropic Gr MREs are observed. We can see that the carbonyl iron particles array in chains in the anisotropic MREs and the graphite powders disperse in matrix randomly. Graphite powders contribute to the magnetorheology of MREs such as increasing the initial mechanical properties and diminishing the MR effect. Also the graphite powders connect different carbonyl iron chains parallelly, which helps to reduce the total resistance of MREs.
The conductivity of Gr MREs is affected by three factors. The first is the weight fraction of graphite in the Gr MRE samples; the more weight fraction of graphite is, the more conductive Gr MRE sample is. The external force applied on the samples is another factor. Increasing external force can cause the electrical resistance decrease. The other cause affecting sample conductivity is the intensity of magnetic field. When the intensity rises, the resistance of samples goes down. This paper introduces the Gr MREs’ fabrication process, analyzes the relationship between the resistance of Gr MREs, the external force and the intensity of magnetic field and shows the data gotten from the experiments.