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Experimental investigation on improving electromechanical impedance based damage detection by temperature compensation

: Siebel, Thomas; Lilov, Mihail


Basu, B.:
Damage Assessment of Structures X : 10th International Conference on Damage Assessment of Structures, DAMAS 2013 held at Trinity College Dublin, Ireland from 8-10 July 2013
Dürnten: Trans Tech Publications, 2013 (Key engineering materials 569-570)
ISBN: 978-3-03785-796-0
International Conference on Damage Assessment of Structures (DAMAS) <10, 2013, Dublin>
Fraunhofer LBF ()
experimental investigation; electromechanical impedance; based damage detection; temperature compensation

The sensitivity of the electromechanical impedance to structural damage under varying temperature is investigated in this paper. An approach based on maximizing cross-correlation coefficients is used to compensate temperature effects. The experiments are carried out on an air plane conform carbon fiber reinforced plastic (CFRP) panel (500mm × 500mm × 5mm) instrumented with 26 piezoelectric transducers of two different sizes. In a first step, the panel is stepwise subjected to temperatures between -50 °C and 100 °C. The influence of varying temperatures on the measured impedances and the capability of the temperature compensation approach are analyzed. Next, the sensitivity to a 200 J impact damage is analyzed and it is set in relation to the influence of a temperature change. It becomes apparent the impact of the transducer size and location on the quality of the damage detection. The results further indicate a significant influence of temperature on the measured spectra. However, applying the temperature compensation algorithm can reduce the temperature effect - at the same time increasing the transducer sensitivity within its measuring area. The paper concludes with a discussion about the trade-off between the sensing area, where damage should be detected, and the temperature range, in which damage within this area can reliably be detected.