NDT inspection of aeronautical components by projected thermal diffusivity analysis

P Venegas,J Perán,R Usamentiaga,I Sáez De Ocáriz

doi:10.1080/17686733.2019.1665298

Abstract

ABSTRACT This paper analyzes the application of an innovative method for thermographic NDT data processing to inspections on real aeronautical components. The results provided by this method are related to thermal diffusivity values obtained by projecting the characteristics of a 3D thermal diffusion model onto one of the coordinate planes. In previous studies, laboratory experiments demonstrated that this method produces a higher increase in the signal-to-noise ratio (SNR) compared to conventional processing algorithms and it also provides a novel way of representing detected defects identifying the area affected by the lateral thermal diffusion effect.

Highlights

Infrared thermography (IRT) is becoming a well-known technology due to its broad application range and special features
The projected thermal diffusivity method has already been analysed with theoretical data computationally produced as well as with experimental data produced by thermographic inspections conducted on samples with calibrated defects [6]
Aeronautical components inspected by IRT nondestructive testing (NDT) and analysed with the Projected thermal diffusivity (PTD) method

Summary

Introduction

Infrared thermography (IRT) is becoming a well-known technology due to its broad application range and special features. Each processing algorithm provides different benefits and is usually more suitable for specific type of materials, defects or heat flow conditions They take the temperature raw data as input and produce output signals that depend on the processing procedure. Projected thermal diffusivity (PTD) analysis is a processing algorithm recently developed [6] that operates with temperature values as input data to produce an output related to diffusivity values. This algorithm has been analysed at laboratory level using specimens with intentionally induced defects. The results obtained were satisfactory with high detectability levels The application of this algorithm to the inspection on real components is the step in the evaluation process. This paper shows the results obtained in a preliminary inspection campaign on real aeronautical parts analysed with the PTD method

Infrared thermographic NDT modelling

Derivation of the projected thermal diffusivity method

Finite thickness without presence of defects c 0

Results in controlled samples

Results in real components

Conclusions and future work