Assessment of uncertainty in damage evaluation by ultrasonic testing of composite structures

Wronkowicz, Angelika; Dragan, Krzysztof; Lis, Krzysztof

doi:10.1016/j.compstruct.2018.06.109

Cited by 73 publications

(39 citation statements)

References 5 publications

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“…On the other side, it can be noticed that some parts of damage near the bottom surface of the specimens were also not detected using UT methods, which is due to a reduction of heights of echoes from these damage regions resulting from the distance traveled by the ultrasonic wave as well as resulting from a reflection of the most part of this wave from delaminations located above. More details on these effects one can find in [30]. However, comparing the results obtained for B-and C-Scans one can state that the dead zone in the case of B-Scans is lower with respect to C-Scans, which has a confirmation in all other obtained results.…”

Section: Results Of Fusionsupporting

confidence: 72%

“…However, taking into account also the shape of detected damage, it can be stated that C-Scans brought more accurate information, but with the damage overestimation of about 2.27 mm in each direction. These damage size differences can be explained by many factors influencing on the measurement uncertainty using ultrasonic testing techniques, such as an applied transducer frequency and a beam diameter, which was described in detail in a previous authors' work [30].…”

Section: Evaluation Of Estimation Accuracy Of Bvid Based On Utmentioning

confidence: 99%

“…Due to the fact that UT results usually present under-or over-estimated damage with respect to true damage [30], the damage extent estimation is difficult, since this misestimation introduces uncertainty in the evaluation process. Therefore, it is important to characterize damage mechanisms typical for CFRP structures subjected to low-velocity impact loading depending on specific conditions of such loading as well as to evaluate the amount of misestimation which allows for a minimization of errors in damage extent estimation based on solely UT results.…”

Section: Introductionmentioning

confidence: 99%

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Impact Damage Evaluation in Composite Structures Based on Fusion of Results of Ultrasonic Testing and X-ray Computed Tomography

Katunin

Wronkowicz-Katunin

Dragan

2020

Sensors

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Barely visible impact damage (BVID) is one of the most dangerous types of structural damage in composites, since in most practical cases the application of advanced non-destructive testing (NDT) methods is required to detect and identify it. Due to its character of propagation, there are minor signs of structural damage on a surface, while the internal damage can be broad and complex both in the point of view of fracture mechanisms and resulting geometry of damage. The most common NDT method applied e.g., in aircraft inspections is ultrasonic testing (UT), which enables effective damage detection and localization in various environments. However, the results of such inspections are usually misestimated with respect to the true damage extent, and the quantitative analysis is biased by an error. In order to determine the estimation error a comparative analysis was performed on NDT results obtained for artificially damaged carbon fiber-reinforced composite structures using two UT methods and X-ray computed tomography (CT). The latter method was considered here as the reference one, since it gives the best spatial resolution and estimation accuracy of internal damage among the available NDT methods. Fusing the NDT results for a set of pre-damaged composite structures with various energy values of impact and various types of impactor tips applied for introducing damage, the evaluation of estimation accuracy of UT was possible. The performed analysis allowed for evaluation of relations between UT and X-ray CT NDT results and for proposal of a correcting factor for UT results for BVID in the analyzed composite structures.

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Section: Results Of Fusionsupporting

confidence: 72%

Section: Evaluation Of Estimation Accuracy Of Bvid Based On Utmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Impact Damage Evaluation in Composite Structures Based on Fusion of Results of Ultrasonic Testing and X-ray Computed Tomography

Katunin

Wronkowicz-Katunin

Dragan

2020

Sensors

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“…Finally, tqi* is the lifetime value belonging to the peak of the density function of i. The decomposition results make it possible to calculate the reliability and failure mode characteristics according to Equations (41)- (44). Figure 9 shows the fraction of the AE events according to Equation (43) belonging to the four damage modes (D1,…,D4) at different load times.…”

Section: Glass Fiber Reinforced Pp Compositementioning

confidence: 99%

Novel evaluation method of acoustic emission data based on statistical fiber bundle cells

Vas

Kocsis²,

Czigány

et al. 2019

Journal of Composite Materials

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In general, the aim of acoustic emission (AE) assisted tensile tests of composite materials is to identify and characterize the damage and failure modes of the specimens. This paper presents a fiber-bundle-cells (FBC) based statistical model, which provides a possible solution to the problem of characterizing the mechanical and failure behavior of the material. The model, based on the results of mechanical tests and AE measurements, decomposes the measured AE event number and tensile force-load time processes into components corresponding to the different damage modes. The AE events belonging to different failure modes are described by inhomogeneous Poisson point processes, while failures are modeled with the breakage of fibers as elementary parts of the sample. Hence damage modes can be characterized with the number fraction, and the tensile strength and signal energy distributions of the components. Moreover, the variation of the number fraction of the intact or damaged fibers as a function of the load time can be calculated and depicted as well. As reliability function or a kind of damage map, it reveals the mechanical load-bearing ability of the material tested. The applicability of the model is demonstrated by compact tension testing and the comparison of short and long glass fiber reinforced VERTON PP sheets and injection molded wood fiber reinforced PP composites.With the help of fast Fourier transformation (FFT), the frequency components of the single AE signals can be characterized by the amplitude or power spectrum in the frequency domain. Their description parameters are the bandwidth (B), the mean frequency (fm), the frequency of the maximum amplitude component (fP), and the amplitude (AP) or energy (UP) of the maximum peak. Similar parameters can be obtained from the mean spectra of a series of AE signals, and histograms and/or cross-plots can be calculated from the data of single AE signals. 2,4 Special techniques can provide information in both the time and the frequency domain, resulting in time-dependent spectrum statistics. 2,4 The classic method is the short time FFT (SFFT) technique, which uses a moving time window. In the case of wavelet transformations (WT), AE signals are analyzed with the help of various wavelet components. The signal transformations mentioned above provide additional or in itself usable information about the sources and failure modes in the frequency domain [21][22][23][24][25][26] or both in the time and the frequency domains [27][28][29][30][31][32][33][34][35][36] . In the latter case, wavelet transformations based on Haar 28 or Gabor 27, 33 wavelet components as well as Hilbert-Huang transform 30 can be used to decompose the AE signals and calculate the energy of the components. [27][28][29][30][31][32][33][34][35][36] In the case of thin plates, modal analysis can be applied to study and separate extensional and flexural Lamb waves. 37,38 The finite element method (FEM) can give a good base for wave discrimination. 38 The localization of a single AE signal in the spe...

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“…However, there are numerous factors influencing on the damage detectability and the occurrence of measurement errors during performing ultrasonic inspections. In the paper [64], the authors presented a study on the uncertainty assessment connected with the selection of techniques and parameters of ultrasonic testing that affects the damage size estimation significantly. This paper is focused on the uncertainty assessment connected with the post-processing of ultrasonic data obtained after the inspection.…”

Section: Ultrasonic Testing Of Composite Materialsmentioning

confidence: 99%

Uncertainty Estimation for Ultrasonic Inspection of Composite Aerial Structures

et al. 2019

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Components made of polymeric composite materials, such as wings and stabilizers of aircrafts, are periodically inspected using non-destructive testing methods. Ultrasonic testing is one of the primary inspection methods applied in the aircraft/aerospace industry. Image processing methods have been developed for the purpose of ultrasonic data analysis and increasing the inspection efficiency. A critically important factor in damage sizing is appropriate processing of ultrasonic data in order to extract the damage region properly before calculation of its extent. The paper presents a comparative analysis of various image segmentation methods in the light of accuracy of damage detection in ultrasonic C-Scans of composite structures. A brief review of image segmentation methods is presented and their usefulness in the ultrasonic testing applications is discussed. The selected methods, namely the threshold-, edge-, region-, and clustering-based ones, were tested using ultrasonic C-Scans of a specimen with barely visible impact damage and aircraft panels with delamination, all made of CFRP composites. A problem with the selection of appropriate input parameters using most of the segmentation methods is discussed, and non-parametric histogram-based approaches are proposed. A quantitative analysis of the accuracy of damage detection using the segmentation methods is presented and the most suitable approaches are introduced. The proposed processing procedures may significantly improve the objectivity of inspections of composite elements and structures using ultrasonic testing.

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Assessment of uncertainty in damage evaluation by ultrasonic testing of composite structures

Cited by 73 publications

References 5 publications

Impact Damage Evaluation in Composite Structures Based on Fusion of Results of Ultrasonic Testing and X-ray Computed Tomography

Impact Damage Evaluation in Composite Structures Based on Fusion of Results of Ultrasonic Testing and X-ray Computed Tomography

Novel evaluation method of acoustic emission data based on statistical fiber bundle cells

Uncertainty Estimation for Ultrasonic Inspection of Composite Aerial Structures

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