A New Method for Characterizing the Dynamic Properties of Electroviscoelastic Materials

摘要

A direct method for determining the dynamic stiffness properties of electroviscoelastic materials is described. Electroviscoelastic materials (EVEMs) are characterized as having stiffness and damping properties that vary with frequency, temperature, and applied voltage. The test system described allows the direct measurement of the complex stiffness (shear modulus, loss factor) of EVEMs at varying voltages and temperatures. Design of the test apparatus incorporates a double-lap shear type refrigerated test fixture utilizing a laser vibrometer to measure the dynamic response of the moving mass subjected to a periodic chirp excitation. A refrigeration system controls the temperature of the moving mass, stationary masses, and test specimens in order to study the effect of temperature on dynamic material property behavior. The test system is first validated by measuring the dynamic properties of a known viscoelastic damping material as function of frequency and temperature. Second the material properties of an EVEM are studied as a function of frequency only. The EVEM consists of poly (p-phenylenes) particles doped with FeCl_3 suspended in a blended silicone gel, which reacts to an electric field. Techniques addressing data reduction, mechanical compliance, and electrical insulation are discussed.