ON THE APPLICATIONS OF ELECTRORHEOLOGICAL FLUIDS TO THE DEVELOPMENT OF SEMIACTIVE SUSPENSION SYSTEMS FOR GROUND VEHICLES

The resistivity, dielectric constant, response time and shear strength of two types of electro-rheological fluid were measured under various electric field strengths, shear rates and operating temperatures. It is found that the ER fluids tested have fast response suitable for con tinuously adjustable dampers. However, their electrical and mechanical properties are highly dependent on operating temperature. They are fo und to be unsuitable for use in sub-zero temperatures. Various design configurations of ER dampers were examined. ER dampers based on the fl ow-mode and multi-step control principles were tested using a model te st facility. It is shown that these ER dampers can provide a wide rang e of damping ratios between approximately 0.1 and 1.5. The control str ategies, including on-off control, discrete damping control and contin uous control, for active dampers were investigated using computer simu lation techniques, as well as experimentally. It is found that a semi- active suspension system with ER dampers employing the continuous cont rol strategy has the potential of providing ground vehicles with signi ficantly improved ride comfort, in comparison with the conventional pa ssive suspension.