Data-fitting reconstruction for defect inspection of airplane aluminum structure in infrared thermographic NDT

摘要

Infrared (IR) thermography has already demonstrated to be an effective tool for nondestructive testing and evaluation (NDT & E) applications. Pulsed thermography (PT) is such kind of technique often used in rapid and wide-area sub-surface inspection. In aviation industry, metal structures of aluminum, which has high thermal conductivity and diffusivity, usually need to be verified in material integrality both for manufacture and maintenance. And it is generally difficult to get sufficient noise-free sampling data for an accurate analysis due to swift heat conduction in material of high thermal conductivity, if the IR device is not good enough for a high sampling rate. So a data-fitting process is offered to reconstruct the sequence from a PT test for cost-effective detection by a commercial mediocre infrared imaging system. This method brings two evident advantages: increased image quality by reducing temporal stochastic noise, and discretionary number of reconstructed frame at any precision for quantitative analysis. A particular specimen of duralumin is machined to emulate airplane components. And experimental difference curves and images are given, behaving well to indicate the validity of this economical inspection.