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134 Investigation to Local Defect Resonance for Non-Destructive Testing of Composites
* 1 , 1 , 1 , 1, 2 , 1 , 1
1  Department of Materials Science and Engineering, Ghent University, Technologiepark-Zwijnaarde 903, 9052 Zwijnaarde, Belgium
2  SIM Program M3 DETECT-IV, Technologiepark-Zwijnaarde 935, B-9052 Zwijnaarde, Belgium


Local defect resonance (LDR) makes use of high frequency vibrations to get a localized resonant activation of a defective region. In this study, the LDR behavior of carbon fiber reinforced polymer (CFRP) coupons with three different types of damages is investigated using broadband measurements obtained with a scanning laser Doppler vibrometer (SLDV). First, the LDR response of flat bottom holes of different depths and sizes is evaluated using a signal-to-noise ratio. Next, results are obtained for ETFE inserts where the difference between (artificial) delaminations and inserts is outlined. At last, the vibrational response of a CFRP coupon with barely visible impact damage is investigated. This type of damage has a more complex structure, and it is shown that frequency band data (an alternative to the single frequency LDR) performs well in identifying such complex damage.

Keywords: Local defect resonance (LDR); Frequency Band Data (FBD); Non-Destructive Testing (NDT); Composite materials, Laser Doppler Vibrometry (LDV)