scholarly journals Damage Propagation Analysis in the Single Lap Shear and Single Lap Shear-Riveted CFRP Joints by Acoustic Emission and Pattern Recognition Approach

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 3963
Author(s):  
Claudia Barile ◽  
Caterina Casavola ◽  
Giovanni Pappalettera ◽  
Paramsamy Kannan Vimalathithan
Keyword(s):  
Pattern Recognition ◽  
Acoustic Emission ◽  
Research Work ◽  
Amplitude Distribution ◽  
Acoustic Energy ◽  
Matrix Cracking ◽  
Cumulative Energy ◽  
Cfrp Laminates ◽  
Hybrid Joint ◽  
Lap Shear

An innovative way of using the Acoustic Emission (AE) technique is introduced in this research work. The ratio of recorded acoustic energy and the counts recorded for each acoustic event were used for characterizing Carbon Fiber Reinforced Plastic (CFRP) laminates adhesively bonded with and without mechanical fasteners. The cumulative counts and cumulative energy of the recorded acoustic events were used for identifying the critical points of failure under loading of these hybrid joint specimens. The peak amplitude distribution was used for identifying the different damage modes such as delamination, matrix cracking and fiber breakage, albeit, ineffectively. The new parameter energy per count was introduced in this work, which can successfully identify the different damage modes under loading. To differentiate the damage modes using the energy per count, they were clustered using k-means++ pattern recognition technique. The method introduced in this work can estimate the damage modes of the CFRP specimens.

Cumulative acoustic emission energy for damage detection in composites reinforced by carbon fibers within low-cycle fatigue regime at various displacement amplitudes and rates

2021 ◽  
pp. 096739112098570
Author(s):  
Mohammad Azadi ◽  
Mohsen Alizadeh ◽  
Seyed Mohammad Jafari ◽  
Amin Farrokhabadi
Keyword(s):  
Acoustic Emission ◽  
Carbon Fibers ◽  
Polymer Matrix Composites ◽  
Low Cycle Fatigue ◽  
Energy Parameter ◽  
Fatigue Tests ◽  
Matrix Cracking ◽  
Matrix Composites ◽  
Cycle Fatigue ◽  
Cumulative Energy

In the present article, acoustic emission signals were utilized to predict the damage in polymer matrix composites, reinforced by carbon fibers, in the low-cycle fatigue regime. Displacement-controlled fatigue tests were performed on open-hole samples, under different conditions, at various displacement amplitudes of 5.5, 6.0, 6.5 and 7.0 mm and also under various displacement rates of 25, 50, 100 and 200 mm/min. After acquiring acoustic emission signals during cycles, two characteristic parameters were used, including the energy and the cumulative energy. Obtained results implied that the energy parameter of acoustic emission signals could be used only for the macroscopic damage, occurring at more than 65% of normalized fatigue cycles under different test conditions. However, the cumulative energy could properly predict both microscopic and macroscopic defects, at least two failure types, including matrix cracking at first cycles and the fiber breakage at last cycles. Besides, scanning electron microscopy images proved initially such claims under all loading conditions.

scholarly journals Effect of the Reinforcement Phase on Indentation Resistance and Damage Characterization of Glass/Epoxy Laminates Using Acoustic Emission Monitoring

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
C. Suresh Kumar ◽  
K. Saravanakumar ◽  
P. Prathap ◽  
M. Prince ◽  
G. Bharathiraja ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Glass Fiber ◽  
Research Work ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Cumulative Energy ◽  
Static Indentation ◽  
Felicity Ratio ◽  
Woven Glass Fiber ◽  
Energy Absorbing

The effect of reinforcement phases on indentation resistance and damage behavior of glass/epoxy laminates was investigated in this research work. Woven glass fiber mat and nonwoven chopped glass fiber mat were used as fiber reinforcement phases for fabricating the laminates. Low-velocity impact and quasi-static indentation tests were performed on both laminates to investigate the contact behavior and energy-absorbing capability. Moreover, the acoustic emission (AE) technique was employed to monitor the indentation damage resistance. AE parameters including normalized cumulative counts (NCC), normalized cumulative energy (NCE), rise angle (RA), and felicity ratio (FR) were analyzed. The bidirectional laminates showed premature load drops and drastic changes in the normalized cumulative counts/energy profile in the beginning of loading cycles, indicating the development of macrodamage such as debonding/delamination. AE sentry function results of bidirectional laminates show longer PII function at the earlier stages, associated with minor PIII function and greater PIV function, indicating the continuous degradation and progression of damage. In contrast, the chopped laminates exhibited superior postimpact performance than the bidirectional laminates. The presence of randomly oriented fibres prevents the delamination crack propagation during compression loading, which was attributed with the increased residual compressive strength.

Damage assessment of carbon fibre reinforced plastic using acoustic emission technique: experimental and numerical approach

2020 ◽  
pp. 147592172094643
Author(s):  
Claudia Barile ◽  
Caterina Casavola ◽  
Giovanni Pappalettera ◽  
Vimalathithan Paramsamy Kannan
Keyword(s):  
Finite Element ◽  
Acoustic Emission ◽  
Carbon Fibre ◽  
Crack Length ◽  
Research Work ◽  
Numerical Approach ◽  
Acoustic Energy ◽  
Reinforced Plastics ◽  
Reinforced Plastic ◽  
Carbon Fibre Reinforced Plastic

In this research work, the acoustic emission results obtained from testing double cantilever beam specimens with carbon fibre reinforced plastic laminates are analysed. The acoustic emission descriptors such as amplitude, frequency centroid, counts, duration and risetime are clustered using k-means++ algorithm. An unconventional and innovative way of using the acoustic emission descriptors, after the clustering, is introduced. This method can favourably be used for relating the different damage progression modes in fibre reinforced plastics. Apart from this, the cumulative acoustic energy is used for predicting the crack length of the specimens. The predicted crack length is almost identical to the actual crack length opening recorded in each specimen. Finally, analytical and finite element models are used for validating the experimental results under the mode I delamination. The finite element studies are carried out using cohesive zone modelling in Comsol Multiphysics® platform.

Health monitoring of sandwich composites with auxetic core subjected to indentation tests using acoustic emission

2021 ◽  
pp. 147592172110539
Author(s):  
Khawla Essassi ◽  
Jean-Luc Rebiere ◽  
Abderrahim EL Mahi ◽  
Mohamed Amine Ben souf ◽  
Anas Bouguecha ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Experimental Tests ◽  
Damage Mechanism ◽  
Recognition Algorithm ◽  
Acoustic Energy ◽  
Matrix Cracking ◽  
Sandwich Composite ◽  
Cumulative Number ◽  
The Core ◽  
Number Of Cells

The quasi-static indentation behavior of an eco-sandwich composite with auxetic core consisting of polylactic acid reinforced with flax fibers will be discussed in this article. The structures involved in the test were manufactured using 3D printing technique. Four configurations with different number of cells in the core, were tested. It is found that sandwiches with high number of cells are stiffer and dissipate more energy. Experimental tests were monitored with acoustic emission technique in order to detect the appearance and the evolution of damage behavior. An unsupervised pattern recognition algorithm was used to post process the acoustic emission signals. The classification is conducted using k-means algorithm. Results show that there are three different classes of events for each configuration, which are the core cracking, the matrix cracking and the fiber/matrix debonding. The evaluation of the contribution of each damage mechanism on the total amount of failure was deduced according to the amplitude range, the cumulative number of hits and the acoustic energy activity. Furthermore, macroscopic and microscopic observations were performed in order to correlate acoustic emission classes with the damage mechanisms observed.

Experimental three-point bending test of glass fibre aluminium honeycomb sandwich panel with acoustic emission damage assessment

2021 ◽  
Vol 63 (12) ◽  
pp. 727-733
Author(s):  
A H Abdulaziz ◽  
J McCrory ◽  
K Holford ◽  
A Elsabbagh ◽  
M Hedaya
Keyword(s):  
Acoustic Emission ◽  
Glass Fibre ◽  
Sandwich Panel ◽  
Matrix Cracking ◽  
Bending Test ◽  
Cumulative Energy ◽  
Frequency Spectra ◽  
Test Load ◽  
Three Point Bending ◽  
Honeycomb Sandwich

Due to their complexity, detecting and analysing damage modes in composite honeycomb sandwich panels can be difficult. This article describes the way in which a three-point bending test (3PBT) was performed on a glass fibre aluminium honeycomb sandwich panel (HSP). Acoustic emission (AE) was used to identify damage signals, which were then analysed to determine the positions and characteristics of defects. To locate damage positions, Delta-T mapping was used. The test load was progressively applied in three phases, with the specimen being inspected visually during each phase. A scanning electron microscope (SEM) showed that the most significant damage was local crushing under the test load, which caused matrix cracking, fibre breakage and pull-out. Damage progression and the damage mode were detected using the cumulative energy and frequency spectra of the AE sources for each phase. Matrix cracking frequencies ranged from 30 kHz to 100 kHz, while fibre damage modes ranged from 157 kHz to 322 kHz. The findings highlighted the utility of Delta-T mapping in locating damage positions on sandwich structures under testing. The investigation also emphasised the value of studying frequency spectra and cumulative energy when analysing AE signals.

Acoustic Emission Characterization of Damage Patterns in Composite Scarf Joints Using Unsupervised Learning

2020 ◽  
Author(s):  
D. Xu ◽  
Z. P. Chen ◽  
P. F. Liu ◽  
J. H. Wu ◽  
P. Jiao ◽  
...  
Keyword(s):  
Pattern Recognition ◽  
Acoustic Emission ◽  
Composite Structures ◽  
Tensile Loading ◽  
Matrix Cracking ◽  
Interface Debonding ◽  
Engineering Structures ◽  
Damage Pattern ◽  
Damage Initiation ◽  
Non Destructive

Abstract Interest in damage detection and damage pattern recognition of engineering structures by non-destructive techniques has been increasingly growing. As a non-destructive technique, acoustic emission (AE) has developed rapidly to detect dynamic defects and their evolution behaviors of composite structures, based on the transient elastic waves produced by rapid energy release due to the geometry change of structures. In this paper, AE technology is utilized to monitor the real-time condition of the composite scarf joint (SJ) under tensile loading. First, after AE signal acquisition, dimensionality reduction of eight AE features is realized by employing principal component analysis such that the Curse of Dimensionality can be avoided. Second, feature selection is continued by introducing two evaluation indexes, i.e., correlation coefficient and Laplacian score. Third, after the optimal cluster number is determined, damage pattern recognition is accomplished by introducing k-means++ algorithm which explores the distribution of each pattern in the space constructed by four informative AE features. Based on the clustering results, damage initiation and evolution in SJ specimens under tensile loading are subsequently explored. The shear failure of the adhesive layer which is a characteristic damage pattern for SJ specimens shows a relatively-high activity after the early stage. Matrix cracking and fiber/matrix interface debonding are two fundamental damage patterns which keep active in the whole process.

Damage Characterisation of Carbon Fibre Reinforced Composite Plate Using Acoustic Emission

2013 ◽  
Vol 558 ◽  
pp. 184-194 ◽  
Author(s):  
Bizuayehu Y. Mohammed ◽  
Chee K. Tan ◽  
Steven J. Wilcox ◽  
Alex Z.S. Chong
Keyword(s):  
Acoustic Emission ◽  
Carbon Fibre ◽  
Composite Structures ◽  
Composite Plate ◽  
Broad Band ◽  
Research Work ◽  
Source Location ◽  
Matrix Cracking ◽  
Signal Features ◽  
Damage Types

Acoustic Emission (AE) is a sensitive technique which can be used to characterise damage in high strength composite plate. This paper describes an extension to an earlier piece of research work carried out by the ERC which resulted in the successful development of a novel source location methodology for the said material. The previous work concentrated on the source location in plate-like composite structures using acoustic emission. The work presented in this paper focuses on establishing the correlation between the different damage types suffered in the material namely de-lamination, matrix cracking, fibre rupture and stringer to skin debonding with key signal features of the AE activities. Controlled bending tests were initially carried out on laterally grooved slender composite specimens to progressively propagate damage in the weakened region of these specimens. The composite laminate plate itself is made from 16 plies of carbon fibre twill weaved in an epoxy matrix with bidirectional fibre alignments in the 0° and 90° directions with 60/40 fibre-matrix volume composition. These prepared samples were fully instrumented with broad band (100 kHz to 1MHz) Physical Acoustic AE sensors linked to the necessary signal conditioning hardware. The AE events were recorded using a high speed DAQ card accessed by customised software written in LabVIEWTM. Gathered raw data were analysed off-line for key signal features including energy and frequency contents and subsequently correlated to actual damage types. It can be concluded from the empirical evidence that feature vectors are distinct to the type of damage. Results gathered from additional test on the progressive skin-stringer debonding of the same material to failure confirmed the uniqueness of the AE feature trends. An integrated system which is capable of both in-situ location of compromised sites and the diagnostic of flaw types in composite plate can potentially find engineering applications including the structural health monitoring of composite aircraft parts.

Aspects of Strain Rate Effects on Some Composite Materials

2000 ◽  
Author(s):  
Emmanuel O. Ayorinde
Keyword(s):  
Acoustic Emission ◽  
Composite Materials ◽  
Strain Rate ◽  
Matrix Cracking ◽  
Epoxy Composites ◽  
Fiber Architecture ◽  
Strain Rate Effects ◽  
Rate Effects ◽  
General Strain ◽  
Ultrasonic Images

Abstract Effects of moderate straining speed on the material and damage characteristics of beam samples of graphite/epoxy and E-glass/epoxy composites were investigated. The basic fiber architecture utilized was unidirectional, axial layup, but data was also obtained for the 45-degree orientation. Ultrasonic and acoustic emission (AE) inspections were utilized. The acoustic emission records show matrix cracking. The ultrasonic images revealed the regions of failure. The results show that in general, strain rate notably affects material and damage properties.

Acoustic emission waveforms for damage monitoring in composite materials: Shifting in spectral density, entropy and wavelet packet transform

2021 ◽  
pp. 147592172110446
Author(s):  
Claudia Barile ◽  
Caterina Casavola ◽  
Giovanni Pappalettera ◽  
Vimalathithan Paramsamy Kannan
Keyword(s):  
Acoustic Emission ◽  
Spectral Density ◽  
Flicker Noise ◽  
Wavelet Packet ◽  
Research Work ◽  
Wavelet Packet Transform ◽  
Spectral Energy ◽  
Emission Data ◽  
Cfrp Composites ◽  
Damage Process

Signal-based acoustic emission data are analysed in this research work for identifying the damage modes in carbon fibre–reinforced plastic (CFRP) composites. The research work is divided into three parts: analysis of the shifting in the spectral density of acoustic waveforms, use of waveform entropy for selecting the best wavelet and implementation of wavelet packet transform (WPT) for identifying the damage process. The first two methodologies introduced in this research work are novel. Shifting in the spectral density is introduced in analogous to ‘flicker noise’ which is popular in the field of waveform processing. The entropy-based wavelet selection is refined by using quadratic Renyi’s entropy and comparing the spectral energy of the dominating frequency band of the acoustic waveforms. Based on the method, ‘dmey’ wavelet is selected for analysing the waveforms using WPT. The slope values of the shifting in spectral density coincide with the results obtained from WPT in characterising the damage modes. The methodologies introduced in this research work are promising. They serve the purpose of identifying the damage process effectively in the CFRP composites.

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