scholarly journals Investigation on the Behavior of Tensile Damage Evolution in T700/6808 Composite Based on Acoustic Emission Technology

2016 ◽  
Vol 2016 ◽  
pp. 1-9
Author(s):  
Weihan Wang ◽  
Weifang Zhang ◽  
Shengwang Liu ◽  
Xiaoshuai Jin
Keyword(s):  
Acoustic Emission ◽  
Damage Evolution ◽  
Tensile Loading ◽  
Matrix Cracking ◽  
Composite Analysis ◽  
Fiber Breakage ◽  
Interface Damage ◽  
Initial Stage ◽  
The Matrix ◽  
Acoustic Emission Technology

T700/6808 composite has been widely used in aerospace field and the damage in composite will seriously influence the safety of aircraft. However, the behavior of damage evolution in T700/6808 composite when it suffered from tensile loading is seldom researched. In this paper, the acoustic emission (AE) technology is employed to research the process of damage evolution in T700/6808 composite under tensile loading. Results show that the damage in T700/6808 composite is small in the initial stage of tensile loading, and main damage is the matrix cracking. The composite has serious damage in the middle stage of tensile loading, which mainly includes the matrix cracking and the interface damage as well as the fiber breakage. The number of fiber breakages decreases rapidly in the later stage of tensile loading. When it comes into the stage of load holding, the composite has relatively smaller damage than that in the stage of tensile loading, and the fiber breakage rarely occurs in the composite. Analysis of damage modes shows that the criticality of the matrix cracking and the interface damage is higher than the fiber breakage, which illustrates that the reliability of T700/6808 composite could be improved by the optimization of matrix and interface.

Cluster analysis of acoustic emission signals and tensile properties of carbon/glass fiber–reinforced hybrid composites

2019 ◽  
Vol 18 (5-6) ◽  
pp. 1686-1697 ◽  
Author(s):  
Wen-zheng Zhao ◽  
Wei Zhou
Keyword(s):  
Acoustic Emission ◽  
Digital Image Correlation ◽  
Glass Fiber ◽  
Digital Image ◽  
Hybrid Composites ◽  
Correlation Method ◽  
Tensile Loading ◽  
Image Correlation ◽  
Matrix Cracking ◽  
Woven Composites

Understanding the damage and failure of carbon/glass epoxy hybrid woven composites under tensile loading based on acoustic emission signals is a challenging task in their practical uses. In this study, an approach based on fuzzy c-means algorithm is proposed to process the acoustic emission signals from tensile loading of composites monitored by combining acoustic emission technology and digital image correlation method. The results show that the acoustic emission signals from tensile loading can be divided into three clusters. The three clusters correspond to three kinds of damage modes including matrix cracking, fiber/matrix debonding, delamination, and fiber breakage. By comparing the acoustic characteristics of these classes, a correlation procedure between the clusters and the damage mechanisms observed is proposed. Meanwhile, it can be found that debonding and fiber break signals for glass fiber correspond to a lower frequency range than that for carbon fiber. Moreover, the method combining acoustic emission and digital image correlation can effectively monitor the damage process of the specimen both on the inside and outside, which can provide a reference for the health monitoring of composite structure.

Acoustic Emission Test for the Gradual Damage Process of Unidirectional Composites

2013 ◽  
Vol 341-342 ◽  
pp. 105-108
Author(s):  
Xiao Tong Fang ◽  
Wei Fang Zhang ◽  
Deng Jiang Wang ◽  
Sheng Wang Liu
Keyword(s):  
Acoustic Emission ◽  
Matrix Crack ◽  
Interface Fracture ◽  
Fiber Breakage ◽  
Cumulative Impact ◽  
Damage Models ◽  
Impact Rate ◽  
Initial Stage ◽  
Damage Process ◽  
Acoustic Emission Test

The gradual damage progress of unidirectional laminate T700/ epoxy 6808 is investigated by acoustic emission test, and impact rate, impact amplitude, cumulative impact and impact energy in different test stages are measured. The results indicate that the sample suffers from diverse damage models in different loading stages. In the initial stage, damage mode is matrix crack, while other modes like matrix crack/ crack propagation, interface fracture and fiber breakage can be successively detected in the test.

Experimental Characterization of Matrix Cracking Behavior in Thermally Cycled CFRP Laminates

2002 ◽  
Vol 11 (3) ◽  
pp. 287-305 ◽  
Author(s):  
Shinji Ogihara ◽  
Akira Kobayashi ◽  
Takamoto Ishiguro ◽  
Nobuo Otani
Keyword(s):  
Thermal Cycling ◽  
Crack Density ◽  
Tensile Loading ◽  
Matrix Crack ◽  
Matrix Cracking ◽  
Thermal Cycles ◽  
Critical Energy Release Rate ◽  
Cracking Behavior ◽  
Cfrp Laminates ◽  
The Matrix

The effect of thermal cycling on the mechanical properties of composite materials is an important issue in engineering, especially in their applications to the space environment. The present study concerned with the experimental study of both the thermal cycling induced matrix cracking and the effect of thermal cycling on the matrix cracking behavior under tensile loading in CFRP laminates. Two kinds of carbon/epoxy systems, T800H/3631 and T300/2500, are used for the laminate configurations of (0/90)s and (90/0)s. The specimens are thermally cycled between −196 and 100°C. Thermal cycling tests are performed up to 1000 cycles. The polished edge surfaces of specimens are examined by the replica technique, and then the matrix crack density is measured as a function of the number of thermal cycles. It is found that the first matrix cracking in (0/90)s and (90/0)s laminates occurs at almost the same numbers of thermal cycles. It is also found that the matrix crack density increases more rapidly in (0/90)s laminates than in (90/0)s laminates in both material systems. To investigate the effect of thermal cycling on matrix cracking behavior under tensile loading, a series of tensile tests on thermally cycled specimens are performed. The effect of thermal cycling on matrix cracking under tension is evaluated in terms of the change in the critical energy release rate and the critical stress for matrix cracking.

EFFECTS OF HEAT TREATMENT ON THE TENSILE BEHAVIOR AND DAMAGE EVOLUTION OF A 3D C/SIC COMPOSITE

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2591-2596
Author(s):  
YIQIANG WANG ◽  
LITONG ZHANG ◽  
LAIFEI CHENG
Keyword(s):  
Heat Treatment ◽  
Acoustic Emission ◽  
Damage Evolution ◽  
Tensile Behavior ◽  
Matrix Cracking ◽  
Lower Strength ◽  
Strain Behavior ◽  
Pull Out ◽  
Final Failure ◽  
Fiber Preforms

The tensile responses and the associated damage evolutions of a 3D C / SiC composite with and without heat treatment on the fiber preforms were compared. The results show that the composite without heat treatment exhibits a largely non-linear stress-strain behavior up to rupture as well as a lower strength and a strain-to-failure. The damage evolution characterized by acoustic emission indicates the composite failures in the region of matrix cracking multiplication. However, the composite with heat treatment has a larger strength and a strain-to-failure, and the damage evolution indicates that the composite had experienced the region of matrix cracking saturation and then fiber bundle pull-out just prior to final failure. Microstructural observations on the fractured specimens revealed the interfacial bonding between fibers and matrix becomes weaker after heat treatment.

scholarly journals Prediction of fiber breakage and matrix cracking in polymeric composites under low-cycle fatigue regimes by fuzzy and wavelet clustering of acoustic emission signals

2021 ◽  
Author(s):  
Sattar Mohammadi Esfarjani ◽  
Mohammad Azadi ◽  
Mohsen Alizadeh ◽  
Hassan Sayar
Keyword(s):  
Acoustic Emission ◽  
Composite Structures ◽  
Mechanical Test ◽  
Low Cycle Fatigue ◽  
Polymeric Composites ◽  
Matrix Cracking ◽  
Fiber Breakage ◽  
Cycle Fatigue ◽  
Emission Data ◽  
Pull Out

Abstract One of methods for detecting cracks and estimating their growth in materials such as composites is the acoustic emission technique. The detection of damages, cracks and their growth in industrial composite structures, under static and dynamic loads, has a significant importance, in order to prevent any damages and increase the reliability. Therefore, achieving required technical knowledge in this field, can be helpful in repairing and the maintenance of the part in industries. The prediction of the damage in polymeric composites under static loads has been already investigated by researchers; however, under cyclic loadings, researches about this behavior are still rare. In this study, by acoustic emission sensors and analyzing experimental data, the damage, including matrix cracking, the fiber breakage and other damages (debonding, fiber pull-out and delamination) during dynamic loading was investigated. At the first stage, standard specimens were made by the pure resin epoxy and the pure carbon fiber, subjected to monotonic tensile loading and then, the frequency of the failure was extracted. Then, composite specimens were loaded in the low-cycle fatigue regime. Mechanical test results and acoustic emission data were analyzed by fuzzy C-Means and wavelet transform methods and then compared to each other to find the percentage of failures in first, mid- and last cycles by the differentiation of failure types. Results clearly indicated that the acoustic emission approach is useful and an effective tool for identifying and detecting damages in polymeric composites.

Monitoring of Failure Mechanisms in Fiber Reinforced Composites During Cryogenic Cooling by Acoustic Emission

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1763-1769 ◽  
Author(s):  
Nak Sam Choi ◽  
Sung Choong Woo ◽  
Tae Won Kim ◽  
Kyong Y. Rhee
Keyword(s):  
Acoustic Emission ◽  
High Frequency ◽  
Composite Laminates ◽  
Low Frequency ◽  
Cryogenic Cooling ◽  
Reinforced Composites ◽  
Frequency Bands ◽  
Initial Stage ◽  
The Matrix ◽  
Ae Signals

Microfractures in composite laminates during cryogenic cooling were monitored employing thermo-acoustic emission(AE). During the initial stage of cryogenic cooling, very strong AE signals with low and high frequency bands were dominantly detected showing a development of large cracks accompanying fiber breakages. After that, weak emissions with low frequency bands became prevalent indicating the propagation of microfractures in the matrix and/or fiber-matrix interface. It was concluded that the breakage of bridged-fibers hindering the macroscopic cracking in the initial stage might be the representative cryogenic damage of composite laminates.

In situ x-ray CT under tensile loading using synchrotron radiation

1995 ◽  
Vol 10 (2) ◽  
pp. 381-386 ◽  
Author(s):  
T. Hirano ◽  
K. Usami ◽  
Y. Tanaka ◽  
C. Masuda
Keyword(s):  
Synchrotron Radiation ◽  
Tensile Loading ◽  
Ct Images ◽  
Matrix Cracking ◽  
Alloy Matrix ◽  
X Ray ◽  
Sic Fibers ◽  
Matrix Cracks ◽  
The Matrix

Internal damage in metal matrix composite (MMC) under static tensile loading was observed by in situ x-ray computed tomography based on synchrotron radiation (SR-CT). A tensile testing sample stage was developed to investigate the fracture process during the tensile test. Aluminum alloy matrix composites reinforced by long or short SiC fibers were used. The projection images obtained under tensile loading showed good performance of the sample stage, and matrix deformation and breaks of the long SiC fibers could be observed. In the CT images taken at the maximum stress just before failure, debondings of the short SiC fibers to the matrix, many pullouts of the fibers, and matrix cracking could be clearly observed. The in situ SR-CT allowed the observation of generation and growth of such defects under different tensile stress levels. The results from the nondestructive observation revealed that the MMC was broken by propagation of the matrix cracks which might be caused by stress concentration at the ends of the short fibers. A three-dimensional CT image reconstructed from many CT images provided easy understanding of the fiber arrangement, crack shape, and form of the void caused by fiber pullout. In situ SR-CT is a useful method for understanding failure mechanisms in advanced materials.

Analysis of Formation of the Critical State in Tensile Failure of Unidirectional Composites

2015 ◽  
Author(s):  
Linqi Zhuang ◽  
Ramesh Talreja
Keyword(s):  
Tensile Loading ◽  
Matrix Cracking ◽  
Fracture Plane ◽  
Fe Model ◽  
Load Bearing Capacity ◽  
Fiber Failure ◽  
Load Bearing ◽  
Critical Fracture ◽  
The Matrix ◽  
Fiber Breaks

Unidirectional (UD) composites are building blocks in most load bearing structural components for lightweight applications in aerospace, automotive and wind energy industries. The loss of the structural load bearing capacity is governed by the instability of the fiber breakage process in the UD composites. When subjected to increasing or repeated tensile loading along fiber direction, the first failure event within these composites occurs as discrete fibers break at weak points followed by fiber/matrix debonding due to high stress concentration caused by fiber breaks. Upon further loading, or on repeated loading, more fiber breaks occur along with other accumulated damage events such as debond growth and matrix cracking. Final failure of a UD composite occurs when a critical fracture plane is formed by interconnecting individual broken fibers and associated debonding through matrix cracking. This failure process has emerged from numerous experimental studies, which also suggest that the critical fracture plane contains only a small number of broken fibers for commonly used composites such as glass/epoxy and carbon/epoxy. However, the mechanisms underlying the critical fracture plane formation are not clear. As the first step to clarify the creation of a critical fracture plane, the conditions for connectivity of a broken fiber end with neighboring broken fibers is studied in this work. In order to investigate the local stress field surrounding the broken fiber, a finite element (FE) model is constructed in which six neighboring fibers are placed as a ring of concentric axisymmetric cylinder embedded in the matrix. The discrete fiber region is surrounded by a concentric outer cylinder ring of homogenized composite. The entire FE model is subjected to axial tensile loading. To account for the consequence of the stress enhancement at the broken fiber end, a debond crack at the fiber/matrix interface extending a short distance from the fiber end is included in the analysis. Realizing that the debond crack by itself would not connect with other fiber failures, focus of the stress and failure analysis is placed on deviation of the debond crack laterally into the matrix. For this purpose, matrix cracking in two possible modes — ductile and brittle — is considered, Energy based criteria are used to study the competition between the cracking modes and the crack path into the matrix from the end of debond to the neighboring fibers is determined. Next the failure of the neighboring fibers caused by the intense stress field accompanying the matrix cracks is studied. The conditions for generating a plane connecting the initially broken fiber end to subsequent fiber failures are finally determined. Further ongoing studies are aimed at clarifying the limiting conditions for avoiding the fiber failure criticality, and thereby improving the load bearing capacity of UD composites. The statistical considerations regarding fiber failure will also be incorporated in these studies.

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