The Temperature Dependent Damping Behavior of Novel Nanocomposites for Structural Materials Applications
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The Temperature Dependent Damping Behavior of Novel Nanocomposites for Structural Materials Applications Ramazan Asmatulu,1 Rick Claus,1,2 Jeff Mecham,2 and Dan Inman,3 1
Fiber & Electro Optics Research Center, Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, VA 24061, 2 NanoSonic Inc., 1485 South Main Street, Blacksburg, VA 24060, 3 Center for Intelligent Materials, Virginia Tech, Blacksburg, VA 24061. ABSTRACT Near nanoscale fine particles including vanadium dioxide (VO2) and zinc oxide (ZnO) were incorporated into matrix materials (tin and polymer adhesives). A number of mechanical damping tests were conducted on the prepared composite materials at frequency ranges of 0 - 2 kHz and over a broad temperature range. The mechanical vibration test results showed that VO2 and ZnO gave significantly higher negative-stiffness (or damping) at approximately 68 °C (155 F) and 29 °C (85 F). For example, approximately 15% and 12% damping values were achieved at first and second resonance frequencies, respectively, which can potentially prevent vibration on the materials. This significant improvement on the damping of the nanocomposite material may be because of the ferroelasticity, viscoelasticity and/or interfacial sliding at those particular temperatures. It was also observed the etching of substrate surfaces improved adhesion and contributed consistent results to vibration testing reproducibility. Thus, it is concluded that nanocomposite existing damping properties can be an important method to achieve large damping responses over a broad temperature range. INTRODUCTION The developments of stable and cost effective high performance materials and systems are essential for spacecraft and aircraft, transportation vehicle, marine, building (for earth quake) and other constructions industries [1-4]. In order to obtain such materials, research is very important on smart nanocomposites materials, which can provide promising results in many fields. In the nanocomposite production, individual materials are combined each other to exhibit substantially better properties of composites. As stated, there are two main elements in a nanocomposite material: reinforcement (i.e., fibers, whiskers, particles, flakes, filler and laminar) and matrix materials (i.e., metals and alloys, polymer and ceramics), which can greatly improve the mechanical properties of the materials as well as other physical and chemical properties. For example, the composite materials can be vibration eliminators for damping, corrosion, oxidation and wear resister and thermally and electrically conductor/isolator [2,3]. As known, some of the mechanical failures of materials come form mechanical vibration because of the fatigue and crack propagation on the materials. For this reason, several fatal accidents can take place, and also cause billions of dollars damages annually. Recently, it is stated that many of the damping materials have multi-phase structures. The basic concept of damping is to absorb the external energy th
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