Papers by Author: Xian Zhou Zhang

Abstract: This paper presents the development of a variable stiffness and damping isolator using magnetorheological (MR) fluid technology. The MR fluid isolator is composed of two variable volume rubber bladder filled with MR fluid, a pipe and a MR valve connecting them. One of the bladders supports disturbance force and the MR fluid flows between two bladders because of the variation of bladder volume due to deformation. The shear stress of the MR fluid in MR valve is varied by an applied magnetic field, which thereby varies the characteristics of the isolator, such as its stiffness and damping. A mathematical model of the isolator was derived, and a prototype of the MR fluid bladder spring was fabricated and its dynamic behavior was measured in vibration force for a wide range of frequencies under various applied magnetic fields. The parameters of the model under various magnetic fields were calculated and the bladder dynamic performances were evaluated. A non-resonant control was employed to minimize the vibration amplitude of the system. Numerical simulation results indicated that the semiactive control system produced much better isolation performance than a passive system.

Abstract: This paper presents both theoretical and experimental study of particle motion in a typical interdigitated electrode array. Both finite element method and numerical simulation were performed to predict the movement of particles. The simulation results indicated that the particle motion and separation behaviors strongly depend on the combined contributions of a number of parameters, such as the frequency of the electric field, applied voltage, dielectric properties of the particles and the surrounding medium.

Abstract: This paper presents the study of rheological and mechanical properties of MR elastomers fabricated using small and large particle. Analysis indicated that MR elastomers fabricated with bimodal particles at a specific particle ratio ingredient show enhanced MR effect compared with those fabricated with monoparticles. MR elastomer samples were fabricated by using small and large particles with sizes of 5m and 50m respectively. Their rheological and mechanical properties were characterized with a MR rheometer. Experimental results agree well with the analysis.

Abstract: This paper presents fabrication and characterizing of a new functional material, magnetorheological shear thickening fluid (MRSTF), by mixing micron-sized magnetizable particles with nano-sized silica particle based shear thickening fluid. Dynamic properties of the MRSTF were characterized by using a parallel-plate rheometer. The effects of steady-state shear rate and magnetic field on MRSTF rheological properties were addressed. The suspension shows an abrupt increase in complex viscosity beyond a critical dynamic shear rate and a magnetic field controllable characteristic, as well as reversible.