Quadratic frequency modulated thermal wave imaging for non-destructive testing

Abstract

Thermal non-destructive testing and evaluation of glass fibre reinforced plastic materials has gained more importance in aerospace industry due to low weight and high strength capabilities in severe environmental conditions. More recently, pulse compression favorable non-stationary excitation schemes have been exhibiting reliable defect detection capabilities in infrared non-destructive testing. This paper introduces a novel infrared non-destructive testing method based on quadratic frequency modulated thermal wave imaging with pulse compression for characterization of glass fibre reinforced plastic materials. Defect detection capability of the proposed method has been experimentally validated using a glass fiber reinforced plastic (GFRP) sample with embedded Teflon inserts. Experimental results proved the enhanced depth resolution capability of the proposed excitation method as compared to the linear frequency modulation with pulse compression.