Impact damage detection system for sandwich structures was developed by using a specific response of pre-pump pulse Brillouin optical time domain analysis (PPP-BOTDA) sensing system to non-uniform strain distribution along an optical fiber. The innovative PPP-BOTDA sensing system employs stimulated Brillouin scattering in the optical fiber and realizes distributed strain measurement with spatial resolution of 10 cm, sampling interval of 5 cm and sensing range of more than 1 km. First, it was revealed that strain gradient broadens a width of a Brillouin gain spectrum, which is a respondency of the PPP-BOTDA. Then the specific response of the PPP-BOTDA was employed to detect non-uniform strain distribution along a dent of the facesheet in a damaged area. As the damage became larger, the width of the Brillouin gain spectra became broader. Consequently, location and size of barely visible damage could be estimated. The developed system can be used in a first inspection of large sandwich structures in aerospace applications.
Barely visible impact damage detection in sandwich structures using non-uniform strain along optical fiber sensors
2007
7 Seiten, 14 Bilder, 14 Quellen
Conference paper
Storage medium
English
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