Advanced NDT Methods and Data Processing on Industrial CFRP Components

Abstract

In this work, enhanced thermal data processing is developed with experimental procedures, improving visualization algorithm for sub-surface defect detection on industrial composites. These materials are prone to successful infrared nondestructive investigation analyses, since defects are easily characterized by temperature response under thermal pulses with reliable results. Better defect characterization is achieved analyzing data with refined processing and experimental procedures, providing detailed contrasts maps where defects are better distinguished. Thermal data are analyzed for different CFRP specimens with artificial defects and experimental procedures are verified on real structural aeronautical component with internal anomalies due to impact simulation. A better computation method is found to be useful for simultaneous defect detection by means of automatic mapping of absolute contrast, optimized to identify defect boundaries.

A Brief Review and Advances of Thermographic Image - Processing Methods for IRT Inspection: a Case of Study on GFRP Plate

“…The selected processing methods represent the reference established techniques for evaluation of IRT measurements for detect artificial defects in a GFRP component. As demonstrated in previous works [31,51,52], a recent image processing was proposed by authors as different approach that combines thermal contrast theory equations (1) and (4). The suggested processing method elaborates acquired thermal sequence in contrast images where defect boundaries are automatically visualized on modified thermal contrast maps [52], optimized to facilitate inspections on large areas even for small defects at critical depths and developed for better defect shape reconstruction, using thermal contrast thresholds in similar way of ultrasonic c-scans [53,54].…”

“…These well-established processing methods guarantee robust references for an innovative promising approach, a different contrast processing method, where defect boundaries are automatically visualized on modified thermal contrast maps, optimized to facilitate inspections on large areas even for small defects and developed for better defect shape reconstruction, using thermal contrast thresholds in similar way of ultrasonic c-scans. The main goal of this paper consists of improving and evaluating the proposed processing approach [31] implemented on different material, to be verified with respect to actual reference methods; the proposed algorithm is based on thermal contrast evaluation and subset calculation in a correlation zone, whose main goal consists of improving and evaluating the proposed approach introduced previously by authors on GFRP material, performing deep comparison with different well-established procedures, more suitable defect detection, reducing problematics in terms of cost and longer computing times.…”

Numerical and experimental validation of SMArt thermography for the inspection of wind blade composite laminate

“…The surface temperature contrast is therefore used to investigate the defect detectability, using pulsed transient thermography [25]. A Matlab algorithm that has been previously developed by authors [26] has been used to upload the 3-dimensional matrix of thermal frames and to return selected thermal maps of specimen for various tests, detecting in particular various heat accumulation zones obtained over time, between intact and damaged areas [27]. The basic principles of this algorithm are here recalled in the following to describe the procedure adopted for the data elaboration.…”

“…Moreover, a single defect at a time can be analysed. In order to overcame these difficulties and to enhance the better individuation of defects, a new contrast algorithm has been proposed by authors [24,26], that automates the detection and mapping simultaneously of the local contrast to identify defect boundaries onto the whole surface. In other words, the local contrast is automatically determined investigating the zone with highest temperature in pre-defined areas.…”

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

“…Therefore, a comparative analysis of different methods is preferred to include example results on real parts. In the present paper, a comparative analysis for detectability enhancement is performed on three different cases of study with CFRP elements containing artificial and real production defects and delaminations created also by static load [26,27]. Both standard processing techniques (statistical, contrast and methods based on transforms) and the present author suggested method are evaluated in terms of defect mapping characteristics, using Tanimoto criterion [28] and signal to noise ratio (SNR) [29].…”