A coefficient clustering analysis for damage assessment of composites based on pulsed thermographic inspection

Abstract

This paper introduces a coefficient clustering analysis method to detect and quantitatively measure damage occurring in composite materials using pulsed thermographic inspection. This method is based on fitting a low order polynomial model for temperature decay curves, which (a) provides an enhanced visual confirmation and size measurement of the damage, (b) provides the reference point for sound material for further damage depth measurement, (c) and reduces the burden in computational time. The performance of the proposed method is evaluated through a practical case study with carbon fibre reinforced polymer (CFRP) laminates which were subjected to a drop impact test with varying energy levels. A novel method for reducing an entire thermogram sequence into a single image is introduced, which provides an enhanced visualisation of the damage area

Recent Advances in Active Infrared Thermography for Non-Destructive Testing of Aerospace Components

“…The experimental results, achieved with a FPA SBF125 IR camera (Santa Barbara, Lowell MA, USA) and two photographic flash lamps (FX60, Glamox, Borehamwood, UK) powered at 6.4 kJ, showed an increase in the SNR for 96% of defects after processing the images with the PLST technique. Zhao et al [ 52 ] used the Coefficient Clustering Analysis (CSA) method coupled to PT, whilst Chang et al [ 49 ] employed the Multi-dimensional Ensemble Empirical Decomposition (MEEMD) algorithm to quantify material damage in impacted CFRP composites. Pawar and Vavilov [ 48 ] used a 3D Normalisation Algorithm (3DNA) for PT to compensate the background non-uniformity in both damaged glass and carbon fibre reinforced composites.…”

Diagnosis of Composite Materials in Aircraft Applications–Brief Survey of Recent Literature

“…[36] used the Multi-Dimensional Ensemble Empirical Decomposition (MEEMD) algorithm. Also for CFRP subjected to impact test, the Coefficient Clustering Analysis (CSA) method integrated with PT was applied [37]. Initiation and propagation of fatigues were monitored using Pulsed Phase Thermography (PPT) method.…”

Quantifying Uncertainty in Pulsed Thermographic Inspection by Analysing the Thermal Diffusivity Measurements of Metals and Composites

“…With concepts such as digital maintenance, design for service, and improvements in computing power, it has become even more important to develop new and powerful tools such as the digital twin that are capable of calculating the remaining useful life based on the current health of the component estimated from the NDT data, together with advanced and predictive data analytics, the sources of which come from the historical and general overall knowledge on the behaviour of the component [ 6 ]. Methods such as the principle component analysis, confidence-based data mapping, and the measurement of the actual material property lead to a more accurate level of sentencing the part, ensuring both design conformity and enhancing the reliability of the overall performance of the asset [ 7 , 8 ]. The challenge still remains in providing an understanding of uncertainty that occurs at the process level that makes an impact on the overall measurement itself [ 9 ].…”