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Indexed by:会议论文

Date of Publication:2012-03-12

Included Journals:EI、CPCI-S、Scopus

Volume:8348

Key Words:Thermal insulation system; guided wave; damage detection; disbond defect; integrity monitoring

Abstract:The integrity monitoring of foam based thermal insulation systems is investigated under a load-temperature environment. Guided wave propagation studies are conducted on two specimens using the pitch-catch approach. To receive only the guided wave, the interval distance is 15mm and 20 mm between two adjacent sensors for specimens. The appropriate guided wave modes are generated by changing the excitation signal. To simulate the thermal and load environment of the thermal insulation system, the test piece is assembled on the load-temperature test machine, where the compression load gradually up to 3 tons is applied to the test piece along its axial direction. Different temperatures are applied to two sides of the test piece. The side without the foam is cooled using Liquid nitrogen to -196 degrees C, while the other side with the foam is heated by the thermocouple to 120 degrees C. The guided wave signals are obtained before/after the experiment begins/ends, and also received periodically in the joint work process of the pressure and the different temperatures. Signals processing and damage imaging techniques are combined to demonstrate the possible disbond defect. Experimental results show that the disbond defect between the foam and the substrate can be qualitatively detected, and its expansion could be identified.