Detection of Fiber Cracking By Acoustic Emission

Harris, D.O.; Tetelman, A.S.; Darwish, FA

doi:10.1520/stp35391s

Cited by 25 publications

(12 citation statements)

References 3 publications

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“…Shortly before the composite fails all the fibres are close to their failure strain. Detection of fibre-cracking by optical microscopy and acoustic emission [14] shows that very few fibres are cracked prior to composite failure. Consequently, a small number of fibre breaks rapidly leads to composite failure, because of the stress concentration in regions close to them.…”

Section: Discussionmentioning

confidence: 99%

The tensile fracture behaviour of the aligned Al-Al3Ni and Al-CuAl2 eutectics at various temperatures

1973

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The tensile behaviour of single crystals of the unidirectionally-solidified AI-AI3Ni fibrous and AI-CuAI2 lamellar eutectics has been investigated at ambient and elevated temperatures. Fractured specimens have been studied directly by scanning electron microscopy, and longitudinal sections through each fracture surface by optical microscopy. At low temperatures, fracture of the AI-AIzNi eutectic is caused by the brittle failure of AI3Ni fibres. At intermediate temperatures broken fibres may be present without causing composite fracture, whilst at high temperatures fibre pull-out occurs. The properties of the AI-CuAI2 eutectic are controlled by the brittle CuAI2 phase, except when the temperature is such that both phases are plastic. During fracture at high temperature the AI-CuAI2 eutectic undergoes micromorphological degradation in the vicinity of the fracture surface. q. IntroductionUnidirectionally-solidified eutectics have been studied because their strength coupled with good thermal stability may well give advantages over more conventional materials. The high temperature strength of a number of systems has been measured [1][2][3][4][5] but no work has been done specifically on the fractography of eutectic composites at varying temperatures. Salkind and co-workers [6,7] have studied the tensile properties of aligned polycrystalline A1-AI~Ni fibrous and A1-CuA12 lamellar eutectics up to 773K (500~ They found that the strength of both materials was reduced at elevated temperatures and that the A1-CuAlz eutectic began to show large elongations at temperatures greater than approximately 623K (350~ Crossman et al [8] confirmed these results for the A1-CuA12 eutectic, as did Butcher et al [9] who also observed microstructural coarsening after fracturing at high temperatures. Fractographic techniques have been used to study the room-temperature fracture of aligned polycrystalline A1-A13Ni eutectic in tension [6,7,10] and aligned polycrystalline A1-CuA12 eutectic in tension [6,7,10] and compression [11]. Tidy and Chadwick [12] have used scanning electron microscopy to study fracture surfaces of aligned single crystals of the A1-CuA12 eutectic deformed in bending at various temperatures.The aim of the present work was to study the effect of temperature on the fracture characteristics of aligned single-crystal specimens of the AI-A13Ni eutectic and the A1-CuA12 eutectic. The fracture surfaces were studied by scanning electron microscopy and longitudinal sections were taken through the fracture surfaces and studied by optical microscopy. Experimental procedureAlloys of eutectic composition were made up from aluminium of 99.998 ~ purity and copper and nickel of 99.999 ~ purity. They were melted under argon in recrystallized alumina crucibles and cast into long flat ingots of rectangular cross-section. These ingots were placed singly in graphite moulds, enclosed in a silica tube, and directionally solidified horizontally under

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Section: Discussionmentioning

confidence: 99%

The tensile fracture behaviour of the aligned Al-Al3Ni and Al-CuAl2 eutectics at various temperatures

1973

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“…The energy E released during an AE event is proportional to the square of the initial voltage V 0 of the signal generated by the AE transducer [8]:…”

Section: Total Countsmentioning

confidence: 99%

Modeling and Experimental Analysis of Acoustic Emission from Metal Cutting

Teti

Dornfeld

1989

Journal of Engineering for Industry

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Testing parameters characterizing acoustic emission (AE) detected during metal cutting may be theoretically correlated, in a simple manner, to work material properites, cutting conditions, and tool geometry. Experimental results, obtained during turning by different researchers using different AE techniques, are presented and critically assessed with reference to their reciprocal agreement as well as their agreement with theoretical predictions. A review of current methods for AE analysis is also presented and the correlations between different AE parameters and energy and jkiwer of the detected signals are reported.

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“…If we assume that the acoustic emission signal is a damped sinusoid, then it can be shown [8] that the number of counts per event is proportional to the initial voltage intensity of the event. Since the transducer operates on the basis of the piezeolectric effect, this voltage is proportional to the energy released per event.…”

Section: Discussionmentioning

confidence: 99%

“…It has been observed by several investigators [8] that the magnitude of the acoustic signal emitted by fiber breakage is greater in magnitude than those generated by either matrix cracking or debonding. But, depending upon the material and damage circumstances, debonding can cause relatively large acoustic signals.…”

Section: Acoustic Emission Principalsmentioning

confidence: 96%

Investigation of Acoustic Emission During Fatigue Loading of Composite Specimens

Williams

Reifsnider

1974

Journal of Composite Materials

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Strain and load controlled fatigue tests were run on boron-aluminum and boron-epoxy angle-plied specimens. Acoustic emission data was recorded using a gating technique that eliminated most extraneous noise. Various material parameters were monitored during the test. A good correlation between acoustic emission and damage extent and propagation was obtained. This was evidenced by an apparent first order linear relationship between dynamic compliance and totalized acoustic emission. A basis for an energy based failure model is formulated and discussed.

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Detection of Fiber Cracking By Acoustic Emission

Cited by 25 publications

References 3 publications

The tensile fracture behaviour of the aligned Al-Al3Ni and Al-CuAl2 eutectics at various temperatures

The tensile fracture behaviour of the aligned Al-Al3Ni and Al-CuAl2 eutectics at various temperatures

Modeling and Experimental Analysis of Acoustic Emission from Metal Cutting

Investigation of Acoustic Emission During Fatigue Loading of Composite Specimens

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