Magnetic circuit design for the performance experiment of shear yield stress enhanced by compression of magnetorheological fluids.

The shear yield stress is an important parameter for the industrial application of magnetorheological (MR) fluids. A test equipment was designed and built to perform investigations on the behaviours of compression and shear after squeeze of MR fluids. Mathematical expression of magnetic flux density was further established. Furthermore, the magnetic field distribution of the test device based on two-coil mode and single-coil mode was simulated and compared using finite element analysis(ANSYS/Multiphysics). An experimental test system was fabricated and modified based on the final conditions and simulation results. The compression and shear after squeeze performances of MR fluids were tested. The results showed that a smaller initial gap distance or a larger compressive strain corresponds to a larger compressive stress under the same external magnetic field strength. The shear yield stress after the squeeze of MR fluids increases quickly with the increasing compression stress and the increasing magnetic flux density. This test equipment was thought to be suitable for studying the compression and shear after squeeze performances of MR fluids.