Fail-safe, semi-active controllable magneto-rheological fluid (MRF) shock absorbers for automotive suspension systems

This work presents the theoretical and experimental studies of automotive size magneto-rheological fluid shock absorbers. The theoretical study consists of: development of a fluid model, design of an electromagnet, and development of a heat transfer model for MRF dampers. To characterize the non-Newtonian behavior of the fluid, a theoretical model was developed utilizing a Herschel-Bulkley approach. An electromagnetic finite element analysis was performed to design the electromagnet. Since damping capacity of MRF dampers reduces with heating, a theoretical model was developed to predict the temperature of the prototype devices. Additionally, a fin system was designed to enhance heat transfer from the system.; Two prototype dampers, one without and the other with fins, were constructed to investigate the fin contribution. It was shown that the experimental data matched well with theoretical predictions and fins demonstrated a significant contribution to attenuate temperature rise and, thus, peak force of the prototype MRF dampers.