Application of Pulsed Thermography and Post-processing Techniques for CFRP Industrial Components

F W Panella,A Pirinu

doi:10.1007/s10921-021-00776-8

Abstract

Several studies demonstrate the effectiveness of pulsed thermography for detection and visualization of sub-superficial flaws in composites. Continuous improvement of thermal data manipulation makes active thermography an attractive and powerful inspection method for industrial process control and maintenance aims. Therefore, temperature image-processing is the major ongoing challenge in the thermographic research field. However, the particular interest for thermographic inspections is to be more addressed to its simple and relatively fast industrial application; an appropriate image processing tool should be implemented and verified on industrial components, containing manufacturing and in-service defects. In the proposed research, well-established and previously proposed methods were analysed and compared for different defect typology inside three CFRP components. The main goal is not solely focused on establishing the suitable data processing approach, providing detection limits of processed data in terms of damage type, size and distribution. The aim of proposed work is to present detailed examples of thermal imaging methods applied on similar critical defects, evaluating different results among methods in terms of defects mapping capabilities and Tanimoto evaluation criterion, coupled also with the signal-to-noise ratio as assessment of defect detectability.

Highlights

In recent years, ecological efficiency of aerospace manufacturing and sustainability economic aspects provide a significant incentive for increasing implementation of Carbon Fiber Reinforced Polymers (CFRP) in industrial structures [1, 2]
The computation limit of previous equation clearly occurs in case processing methods provided one single map of results; for these cases, the resulting image computed normalized contrast can be given by difference of two Regions of Interest (ROIs) values from the same map, as in the follows: kn = kd − ki
Based on the previous principles, the second Local Boundary Contrast (LBC) approach has been introduced when only a single map is post-processed by 3D thermal matrix, as seen in statistical methods based on standardization

Summary

Introduction

Ecological efficiency of aerospace manufacturing and sustainability economic aspects provide a significant incentive for increasing implementation of Carbon Fiber Reinforced Polymers (CFRP) in industrial structures [1, 2]. A suitable ND control approach is the critical aspect for component inspection to certain integrity assessment [10]. Pulsed thermography (PT) represents a no-contact and full-field ND technique, widely used for the industrial controls of large composite surfaces due to wide detection area, fast and relatively simple detection [11, 12]. The enhancement of visual image modality, combined with fast and robust temperature processing strategy has significantly grown for a multi-functionality of Infrared thermography for specific industrial applications, characterized by difficult to inspection components or as requirement of faster inspection [13,14,15,16]. The image-processing methods and their continuous improvement make the thermographic inspection even more suitable alternative to popular ND controls, as ultrasonic testing, for different production environments [12, 16]. Different algorithms were proposed to enhance defect detection in terms of dimension, depth and shape [15, 17, 18]

Methods

Results

Conclusion