Intrinsic parameters in the fracture of carbon/carbon composites

Dassios, Konstantinos G.; Kostopoulos, V.; Steen, Marc

doi:10.1016/j.compscitech.2004.10.021

Cited by 18 publications

(8 citation statements)

References 13 publications

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“…Damage in brittle matrix composites is concentrated around propagating matrix cracks; their formation and propagation, most frequently, appears first during testing as a result of the low strength and modulus of the continuous medium compared to the reinforcements. All major CMC damage mechanisms such as interfacial debonding, fiber sliding, bridging, and pull‐out are, in one way or another, a result of crack formation and propagation . Accepting that crack growth is the most severe CMC damage mechanism, hence also the energetically most prominent, a direct quantitative measure of the extent of cracking can be obtained by capturing the energy dissipated during CMC testing.…”

Section: Resultsmentioning

confidence: 99%

“…All major CMC damage mechanisms such as interfacial debonding, fiber sliding, bridging, and pull-out are, in one way or another, a result of crack formation and propagation. 32,33 Accepting that crack growth is the most severe CMC damage mechanism, hence also the energetically most prominent, a direct quantitative measure of the extent of cracking can be obtained by capturing the energy dissipated during CMC testing. Herein, measurement of crack growth in SiC/BMAS composites was made possible by adopting a novel methodology for analyzing the thermal energy dissipated by the material during testing and captured via IRT.…”

Section: Resultsmentioning

confidence: 99%

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Crack Growth Monitoring in Ceramic Matrix Composites by Combined Infrared Thermography and Acoustic Emission

et al. 2013

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The current study proposes a novel methodology for measuring crack growth in composite materials using combined infrared thermography (IRT) and acoustic emission (AE). The technique is tested across a SiC‐fiber‐reinforced ceramic matrix composite while no apparent factor is limiting its usage on composite materials of different nature as well. Compact tension specimens were loaded in tension with unloading/reloading loops and the thermally dissipated energy due to crack growth and other damage mechanisms was captured by IRT with a 100 Hz sampling rate. Crack growth was established by identifying the time instances where the maximum temperature, hence also damage, occurred and then quantifying, by means of control lines, the damage span within the thermograph corresponding to the specific instance. The high accuracy of the proposed technique was validated against optical measurements of crack length. The theoretical crack length predicted by the elastic compliance technique was found to overestimate the experimental findings by at least 25%. Knowledge of the critical level of damage accumulation for material structural health was made possible from AE descriptors such as activity during the unloading part of the cycles. In this study, AE was particularly successful in closely following the actual crack growth measured by IRT, an observation that brings out the potential of the technique for quantitative measurements.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Crack Growth Monitoring in Ceramic Matrix Composites by Combined Infrared Thermography and Acoustic Emission

et al. 2013

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“…During hot-pressing, a carbon-rich layer is formed at the fibers' surface due to the reaction of SiC with the oxides in the matrix [ 30 , 31 ]. This layer provides a weak fibre/matrix interface that is responsible for the development of important energy dissipation mechanisms during loading, such as interfacial debonding, fiber sliding, fiber bridging, and pull-out [ 32 ].…”

Section: Methodsmentioning

confidence: 99%

Damage Accumulation in Cyclically‐Loaded Glass‐Ceramic Matrix Composites Monitored by Acoustic Emission

Aggelis

Dassios

Kordatos

et al. 2013

The Scientific World Journal

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Barium osumilite (BMAS) ceramic matrix composites reinforced with SiC-Tyranno fibers are tested in a cyclic loading protocol. Broadband acoustic emission (AE) sensors are used for monitoring the occurrence of different possible damage mechanisms. Improved use of AE indices is proposed by excluding low-severity signals based on waveform parameters, rather than only threshold criteria. The application of such improvements enhances the accuracy of the indices as accumulated damage descriptors. RA-value, duration, and signal energy follow the extension cycles indicating moments of maximum or minimum strain, while the frequency content of the AE signals proves very sensitive to the pull-out mechanism.

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“…The fatigue limit stress at room temperature is about 60%‐80% of tensile strength (for metal materials, the fatigue limit stress is about 50% of tensile strength), which is much larger than the first cracking stress of matrix. In order to cause fatigue damage of fiber‐reinforced CMCs, matrix cracking needs to appear during the initial cycle, and the fatigue peak stress must be greater than the first matrix cracking stress . During the cyclic loading, the composite modulus decreases, and the width of stress‐strain hysteresis loop and the residual strain increase.…”

Section: Introductionmentioning

confidence: 99%

Mechanical hysteresis and damage evolution in C/SiC composites under fatigue loading at room and elevated temperatures

Reynaud

Fantozzi

2019

Int J Applied Ceramic Tech

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In this paper, the mechanical hysteresis and damage evolution in C/SiC ceramic matrix composites (CMCs) under cyclic tension-tension fatigue loading at room and elevated temperatures in air and in inert atmosphere and different loading frequencies are investigated. The fatigue hysteresis loops models considering multiple matrix cracking modes are developed to establish the relationships between fatigue hysteresis loops, fatigue hysteresis dissipated energy, and fiber/ matrix interface shear stress. The evolution of fatigue hysteresis dissipated energy and interface shear stress vs applied cycles is analyzed. It was found that the interface shear stress degradation rate increases with fatigue peak stress, and loading frequency from 40 to 375 Hz. K E Y W O R D Sceramic matrix composites (CMCs), fatigue, hysteresis loops, interface debonding, interface shear stress, matrix cracking

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Intrinsic parameters in the fracture of carbon/carbon composites

Cited by 18 publications

References 13 publications

Crack Growth Monitoring in Ceramic Matrix Composites by Combined Infrared Thermography and Acoustic Emission

Crack Growth Monitoring in Ceramic Matrix Composites by Combined Infrared Thermography and Acoustic Emission

Damage Accumulation in Cyclically‐Loaded Glass‐Ceramic Matrix Composites Monitored by Acoustic Emission

Mechanical hysteresis and damage evolution in C/SiC composites under fatigue loading at room and elevated temperatures

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