Study of hysteretic damping in small elastomeric structures

This thesis investigates the damping coefficient for silicone rubber micro structures under oscillating applied stresses. These small elastomeric structures are important to the development of Elastomeric Micro Electro Mechanical Systems, or EMEMS, which has recently become a field of interest. Since energy is lost in a damped system, it is generally desirable to minimize the effect of the damping. Although often overlooked, the primary mechanism of this damping results from the hysteresis effect. This complicated phenomenon cannot be described analytically, and it is a primary objective of this thesis to develop a computational algorithm to determine the hysteretic force based on a sequence of past displacements of the rubber. The extent of the damping can be determined by measuring the resonance response of a silicone structure when an oscillating displacement is applied. It is shown that these small silicone rubber structures exhibit the unique characteristic that the damping coefficient is independent of both the amplitude and frequency of the oscillation. This apparent independence of this damping coefficient of small silicone structures makes the use of the elastomer in EMEMS devices look promising. The ability to predict the effect of damping on the behaviour of these structures is crucial to device design, and its independence over a wide range of operating parameters bodes well for widespread use of elastomeric microstructures.Science, Faculty ofPhysics and Astronomy, Department ofGraduat