Bond Quality Inspection of Bonded Surfaces using Microwave NDE

Abstract

Solid rocket motor is an essential component of an aerospace structure. Bond quality of motor casing and insulation layer plays an important role in the mission performance. Different NDE techniques, such as ultrasonics, thermography, X-ray radiography are employed for evaluating the bond quality of the casing. Depending on the type of material, their characteristic features and accessibility of the test object, suitable technique is employed. Microwave non-destructive evaluation (MWNDE) is an emerging NDE technique for characterizing and inspecting dielectric structures. Microwave NDE finds application in the areas of dielectric material characterization, determining thickness variation, defect detection and bond quality inspection. Bond quality of fiber reinforced polymer (FRP) composite or metal with insulation layer inspected by near-field reflection microwave NDE technique is presented in this paper. Results of inspected structures by swept frequency reflection microwave NDE technique in the frequency range 8.2-12.4GHz (X-band) and 12.4-18GHz (Ku-band) respectively are presented.