Unsteady flow modeling of an electrorheological valve system with experimental validation

This paper presents an unsteady flow modeling of an electrorheological (ER) valve system and verifies its effectiveness through experimental investigation. After designing a cylindrical ER valve, a dynamic model for unsteady flow of ER fluid is derived by considering the fluid inertia. The field-dependent pressure drop of the unsteady flow is then calculated and validated with the experimental result. In order to clearly observe the difference between the unsteady flow model and the steady model, the flow rate of the ER valve is analyzed under low frequency and high frequency sinusoidal inputs. In addition, in order to demonstrate the effectiveness of the proposed unsteady flow model, a position control system activated by ER valves is constructed. The dynamic model of the control system is formulated on the basis of the unsteady flow analysis, and control responses such as flow rate, pressure drop and displacement are compared between the unsteady flow and the steady flow models.