Enhancement of Ultrasonic Non-Destructive Evaluation Technique for High Attentuation Composite Materials

摘要

Syntactic foams are hollow particle filled composite materials. The quality assessment and defect detection in polymeric syntactic foams through ultrasonic imaging (UI) poses severe challenges. Two main difficulties in using UI for syntactic foams are identified as (a) presence of numerous interfaces causing internal reflections and increasing the noise level and (b) presence of significant amount of air causing high attenuation. The present paper takes the first step towards obtaining meaningful scans through UI. Solid particle filled composites have been fabricated and their ultrasonic signature response is analyzed. A totally blind novel signal processing non-destructive evaluation technique is introduced to automatically detect ridges in the ultrasonic response signature of the specimen. The results show that the new algorithm developed in this work is successful in detecting ridges at unequal intervals having a difference of over two orders of magnitude in the amplitudes. The detected ridges can be used to estimate the transmission and attenuation coefficients of the sample.