Theoretic And Experimental Study Of Electro-rheological Damper

Electric-Rhological(ER) fluid is a smart material. When it is applied electric field, its viscosity, modulus and yield stress rapidly change and return an original state as electric field canceled. ER technology develops a new path for automotive semi-active intelligent suspension system. Since ER damper has not disadvantage of passive suspension system for a constant damping, complex structure and slow response of mechanical or electrical adjustable damper, active suspension system for complex manufacture, larger energy consumption, high cost. It has rapid response, stepless damping change, lower energy consumption and structure vibration can be optimized controlled. To focus manufacture of ER fluid and development of ER damper, following works have been completed. 1. The material of ER, dispersing particle, is key of ER fluid's performance. This paper analyzes synthetic condition of polyaniline particle. The polyaniline particle synthesized at low temperature has larger molecular weight and higher electro-conductivity , electro-conductivity mismatching constant of polyaniline and silicon oil is larger, ER effect strengthen. Other factors of influencing ER effect such as size and shape of particle, volume fraction, electric field strength, shear rate, temperature are discussed.2. Although there are some theories which interprete the mechanism of ER effect,exact model is not gotten now. Several theories of interpreting the mechanism of ER effect are introduced, polarization mechanism of particle is analyzed.Through test, ER performance is better when polar liquid is added into polyaniline/silicon oil. We analyze chain-formating process of polyaniline/silicon oil/polar liquid and build up chain-forming, net-forming model of double dispersing system through observation of microstructure and induce a new model.3. It is important to set up a mathematic model for an ER damper. There are four working modes of ER damper, flow mode of fixed electrode, shear mode of slide electrode, mixer mode of slide electrode and squeeze damper. The fluid's rheological behavior in cylinder ER damper has been analyzed. Applying the theory of rheodynamics and hydraulic theory, a relationship of damping vs. vibration velocity, electric field strength and gas-filled pressure has been set up. There are three sections of damping force, background damping force of a fluid viscosity, electric damping force ofapplied electric field and pressure of gas. 4. A new gas-filled ER damper is developed. The main structure parameter of influencing ER damper performance are discussed, some design principles of ER damper are given.5. The ER damper is tested in bench test according to national standard, including schematics of damping force vs. displacement of piston, damping force vs. velocity of piston ,etc. for different composition of ER fluids, gas-filled pressure, gap between inner and outside cylinder and temperature. The error of damping force between calculation and test is analyzed. When temperature of ER fluid increases, damping force of damper will decreases. There are two ways to solve this problem, first compensation for higher electric field strength, second improvement of ER fluid.