Controllable Stress of Magnetorheological Fluid Elastomeric Encapsulations

This study experimentally investigated the different designs of magnetorheological fluid elastomeric encapsulations (MREEs) in order to improve their controllable mechanical properties range. To this end, four different MREE design samples were fabricated, and their stress-strain tests were conducted at constant strain rate conditions by using materials testing machines (i.e., Instron and MTS systems). A compact round electromagnet was used to produce four different magnetic field inputs to activate the MRF inside the MREEs. From the measured stress-strain hysteresis loops, the secant modulus and dissipated energy density of the MREEs were obtained, and their controllable ranges by applied current input were also determined. In addition, in order to evaluate the viscoelastic behavior of MREEs, a dynamic mechanical analysis (DMA) was conducted and the complex modulus was obtained under vibratory loading conditions. By comparing the mechanical properties obtained under constant strain rate conditions, as well as vibratory loading conditions, more effective MREE designs were developed to widen the range of controllable mechanical properties when current input was applied to the electromagnet.