Non-Destructive Evaluation of Material Properties as Function of

The Impulse Excitation Technique (IET) is presented as a non-destructive evaluation technique to measure a wide range of material properties as function of temperature. The IET is based on the accurate measurement of the resonant frequency (fr) and internal friction (Q-1) of a vibrating specimen after it has been mechanically excited by a simple tap. For complex samples multiple resonant frequencies can be detected and analysed from the same excitation: The IET is widely recognized as a one of the most reliable standard techniques for measuring the dynamic elastic properties of Youngs Modulus, Shear Modulus and Poissons ratio. Advanced digital signal analysis and data-mining combined with a dedicated build furnace system makes it possible to use this technique for internal friction measurements as well as for elastic properties determination in a wide temperature range (193 K up to 2,200 K). The non-destructive character of the IET makes it possible to measure the evolution of fr and Q-1 over the complete temperature range. Except for the elastic properties and Q-1 at a temperature, the slope of the curve gives information about phase transformations, glass transition temperature, defect analysis (dislocations, interstitials etc.). The IET presented is very useful for quantifying the deterioration of a material due to thermal shock cycles, aging or fatigue tests. Keywords: Impulse Excitation Technique, resonant frequency, internal friction, elastic properties, data-mining