Using Hysteretic Energy to Evaluate Damping Characteristics of Hard Coating on Titanium.

摘要

Current methods of material damping evaluation consist of bending tests involving half-power bandwidth base excitation or free decay methods measured by laser vibrometer. These methods are accompanied by complex, nonlinear strain evaluation; they are vulnerable to undesired air damping; and they require less than commonplace equipment. The measurement of hysteretic energy loss in axial cyclic loading alleviates these difficulties. By using common tensile testing machines, strain is kept linear and air damping is of no concern. Furthermore, the static test section allows for simplified environmental variation for high temperature or high humidity testing. This study set forth to advance and refine the hysteretic energy method for determining material damping properties. Convergence studies were conducted to determine test parameters which produced the most accurate results. Bare titanium bars were tested to compare damping values to current measurement techniques. Boundary conditions were studied to determine the effects of losses for different grip mechanisms. Hard coatings were applied to titanium and tested to determine the feasibility of extracting coating properties using this method.