Comparison of Cooled and Uncooled IR Sensors by Means of Signal-to-Noise Ratio for NDT Diagnostics of Aerospace Grade Composites

Abstract

This work aims to address the effectiveness and challenges of non-destructive testing (NDT) by active infrared thermography (IRT) for the inspection of aerospace-grade composite samples and seeks to compare uncooled and cooled thermal cameras using the signal-to-noise ratio (SNR) as a performance parameter. It focuses on locating impact damages and optimising the results using several signal processing techniques. The work successfully compares both types of cameras using seven different SNR definitions, to understand if a lower-resolution uncooled IR camera can achieve an acceptable NDT standard. Due to most uncooled cameras being small, lightweight, and cheap, they are more accessible to use on an unmanned aerial vehicle (UAV). The concept of using a UAV for NDT on a composite wing is explored, and the UAV is also tracked using a localisation system to observe the exact movement in millimetres and how it affects the thermal data. It was observed that an NDT UAV can access difficult areas and, therefore, can be suggested for significant reduction of time and cost.

A Review of Modern Thermal Imaging Sensor Technology and Applications for Autonomous Aerial Navigation

“…Uncooled sensors, on the other hand, are smaller in both size and weight at the cost of inferior all-around performance. However, the study in [ 31 ], which compared a high-end cooled FLIR Phoenix to the more affordable uncooled system Variocam, showed that the uncooled thermal system could compensate for its lower resolution sensitivity via further image processing. Furthermore, the study also showed that the uncooled thermal sensor was still suitable for use in UAVs for navigation applications by analysing SNR data.…”

Fast, Accurate, and Reliable Detection of Damage in Aircraft Composites by Advanced Synergistic Infrared Thermography and Phased Array Techniques

“…The limitations in available IRT techniques restricted their ability to perform fast and, at the same time, reliable quantitative inspections [30]. The recent development of an advanced variant of IRT, termed Pulsed Phase-informed Lock-in Thermography (PPI-LT), lifted this limitation [20].…”

Wind Turbine Gearbox Condition Monitoring Based on Class of Support Vector Regression Models and Residual Analysis

“…Basic CM techniques include vibration analysis (wheels and bearings of the gearbox, generator bearings), oil analysis, thermography and acoustic monitoring (sensors mounted on the turbine equipment) [8]. Nondestructive testing (NDT) is a common way to evaluate the structural integrity of several underground structures [9,10] and aerospace applications [11]. Furthermore, integration of sensors and data mining based technologies has enabled a reliable monitoring process [12].…”