Mechanics of the push-out process from in situ measurement of the stress distribution along embedded sapphire fibers

Ma, Qing; Liang, Lei; Clarke, David R.; Hutchinson, John W.

doi:10.1016/0956-7151(94)90462-6

Cited by 47 publications

(8 citation statements)

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“…Using R-line essential to determine the stress distribution. The small cross fluorescence, evaluation of the axial and radial stress composection of the fibers useful for reinforcement (typically d Ϸ nents in c-axis sapphire fibers in various matrix materials has 100 m or smaller) precludes standard X-ray analysis, and, in been demonstrated elsewhere to be possible in conjunction with addition, analysis of individual fibers identified in a microscope elasticity calculation 10,17 or by the use of the full piezospectrois generally desirable. As a specific example, in Fig.…”

Section: ⌬I ϭmentioning

confidence: 99%

“…Because of the nature of the holovariety of residual stress problems, as well as the response to graphic gratings in the spectrometer, the collection efficiency is applied stresses, has been studied in Al 2 O 3 -containing monohighly polarized, with the efficiency reaching a maximum when lithic and multiphase materials. [10][11][12] As shown in Fig. 1, the two the E vector of the fluorescence is parallel to the opening closely spaced R lines result from nonphonon radiative trandirection of the entrance slit, and it reduces to zero when E is sitions from its first excited state (2A and E doublet) to its perpendicular to the slit opening.…”

Section: Introductionmentioning

confidence: 97%

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Polarization Dependence of the Cr³⁺ R‐Line Fluorescence from Sapphire and Its Application to Crystal Orientation and Piezospectroscopic Measurement

Clarke

1997

Journal of the American Ceramic Society

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unless microfocus facilities are available. One motivation of The room-temperature polarization characteristics of the the present study is to develop a technique to determine the ruby R lines have been studied by monitoring the fluorescrystallographic orientation of small regions of Al 2 O 3 by studycence intensity as a function of excitation direction relative ing the polarization characteristics of their R-line fluorescence. to the crystallographic axes of the ruby crystal. The R linesAdditionally, precise knowledge of the fluorescence polarizaare strongly polarized in the basal plane but have no pretion is important in stress measurements in polycrystalline ferred vibration direction within the basal plane. However, materials, in which the stress-induced line shifts are averaged the degree of polarization, P, of the R1 and R2 lines is not over all possible crystallographic orientations and a weighting the same, being P R1 ‫؍‬ 87% and P R2 ‫؍‬ 62%. The phenomefunction resulting from the polarization dependence may need non is explained in terms of the absorption anisotropy and to be included. the probability of spontaneous emission. The findings pro-The anisotropic absorption properties have been commonly vide the basis for a high-spatial-resolution spectrophotoused to align optically uniaxial crystals with their optical axes, metric method to determine the optical c-axis of chromiumat least qualitatively. Although the emission process is more doped Al 2 O 3 crystals using the angular dependence of the complex than that of the absorption, the ruby fluorescence intensity ratio of the R2 line to the R1 line. The application should inherit the optically uniaxial properties from the corunto the orientation determination of sapphire fibers embeddum structure. In this work, a series of experiments were perded in composites and the corresponding residual stress formed to study the polarization characteristics of R-line components are discussed together with the possibility of fluorescence. As a result, the intensity ratio (R2/R1) is determeasuring the texture in the Al 2 O 3 polycrystalline thin films mined as a function of the angle between the optical c-axis of such as oxidation scales. Furthermore, the consequences of the crystal and the direction of the E vector of the incident light polarization orientation on piezospectroscopic measureso that it can be used to measure the c-axis orientation in Al 2 O 3 ments are discussed.quantitatively. After a brief description of the experimental procedures, the results obtained are presented in Section III. I. IntroductionThe theoretical interpretation described in Section IV, along with a comparison with previous literature data, is then fol-T HE optical spectra of ruby (Cr 3ϩ -doped sapphire) have been lowed by examples of application of this phenomenon. studied extensively since the late 1950s and are generally considered to be well interpreted in terms of ligand field theory. 1-5 As a result, the polarization of ruby absorption is well under-II. Experimental Details sto...

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Section: ⌬I ϭmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Polarization Dependence of the Cr³⁺ R‐Line Fluorescence from Sapphire and Its Application to Crystal Orientation and Piezospectroscopic Measurement

Clarke

1997

Journal of the American Ceramic Society

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“…It is well known that the fiber/matrix interfacial behavior critically influences the thermomechanical behavior of TMCs. Various examinations have been developed to evaluate mechanical properties of the fiber/matrix interface, such as pull-out test [3,4], fragmentation test [5,6] and push-out test [7,8]. Among these methods, push-out test has been emerging as an important experimental technique for characterizing the interfacial performance of this kind of composites owing to the relative simplicity of preparing specimens and conducting the experiments.…”

Section: Introductionmentioning

confidence: 99%

Analysis on the interfacial shear strength of fiber reinforced titanium matrix composites by shear lag method

Qin

Yang

et al. 2015

Materials Science and Engineering: A

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“…In this contribution we use a piezospectroscopic technique, based on the photostimulated luminescence (fluorescence) from trace Cr 3+ impurities in CV-AI2O3 (Grabner 1978;, to determine the strength distribution of alumina fibres during the fibre bundle test. The piezospectroscopic technique has been developed in the last few years as a non-intrusive measurement of stresses and strains in aluminacontaining materials and structures (Ma Sz Clarke 1993;Sergo et al 1995;Lipkin &: Clarke 1996). We show that piezospectroscopic measurements performed during fibre bundle tests provides a convenient and reliable method for the rapid acquisition of statistical data of fibre strength distributions.…”

Section: Introductionmentioning

confidence: 99%

Mechanism-Based Design for High-Temperature, High-Performance Composites. Book 4

Evans¹,

Leckie²,

Hutchinson³

1997

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The paper describes a phase-sensitive photothermal technique for the determination of the thermal conductance of a crack or interface embedded within a plate of finite thickness. The technique involves sinusoidally-modulated heating at one point on the surface using a focused laser beam and measurement of the phase shift of the thermal wave at some other point. An analysis is presented for the relationship between the phase lag, the modulation frequency, the specimen geometry, and the thermal properties of both the interface and the solid. The technique is demonstrated using a model system comprising two stainless steel disks, with the "interfaces" between them being formed either by simply placing the two disks in contact with each another, or by placing thin layers of polyethylene sheets between the disks. The trends are rationalized on the basis of the thermal properties of the constituents.70:FZ6S(8/12/97)January 13. 1998-3:25 PM/mcf INTRODUCTIONThe present article describes a photothermal technique and the associated analysis for the determination of the thermal conductance of a crack or interface embedded within a plate of finite thickness. The technique is based on periodic heating at a point on one surface, using, for example, a focused laser beam, and measurement of the phase lag of the thermal wave at some other point. In the absence of an interface, the technique can be used to determine the thermal diffusivity of the material. The work is motivated by concurrent studies on the thermal conductance of delamination cracks in fiber-reinforced ceramic matrix composites (CMCs) and its effect on failure in the presence of a temperature gradient. An example of such a crack is shown in Fig. 1. Although the technique is being developed mainly to study CMCs, it can be applied readily to other problems involving interfaces or cracks in multilayered or coated systems.Photothermal techniques have been used extensively to study the thermal properties of materials [1][2][3][4][5][6][7][8][9][10][11][12]. A recent summary of these can be found in [12]. The techniques have been used also as nondestructive tools for detecting sub-surface defects [12][13][14][15][16][17][18]. The focus of the present work is on one specific subgroup of these techniques, notably, that based upon periodic heating and phase lag measurement.The main advantage of the present technique is that it provides quantitative information about the thermal conductance of cracks and interfaces, rather than simply identifying regions where such defects are present. This information is crucial for failure prediction in a broad range of technological systems, including delamination of thermally-loaded CMC structures, multilayered power electronic devices and thermal barrier coatings.In the past, thermal conductances have been measured predominantly by dc techniques [19][20][21][22]. These techniques require a heat flux, q, to flow through the 70:FZ6S(8/12/97)January 13, 1998*3:25 PM/mcf interface as well as through the bulk of the two contacting s...

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Mechanics of the push-out process from in situ measurement of the stress distribution along embedded sapphire fibers

Cited by 47 publications

References 10 publications

Polarization Dependence of the Cr³⁺ R‐Line Fluorescence from Sapphire and Its Application to Crystal Orientation and Piezospectroscopic Measurement

Polarization Dependence of the Cr³⁺ R‐Line Fluorescence from Sapphire and Its Application to Crystal Orientation and Piezospectroscopic Measurement

Analysis on the interfacial shear strength of fiber reinforced titanium matrix composites by shear lag method

Mechanism-Based Design for High-Temperature, High-Performance Composites. Book 4

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Mechanics of the push-out process from in situ measurement of the stress distribution along embedded sapphire fibers

Cited by 47 publications

References 10 publications

Polarization Dependence of the Cr3+ R‐Line Fluorescence from Sapphire and Its Application to Crystal Orientation and Piezospectroscopic Measurement

Polarization Dependence of the Cr3+ R‐Line Fluorescence from Sapphire and Its Application to Crystal Orientation and Piezospectroscopic Measurement

Analysis on the interfacial shear strength of fiber reinforced titanium matrix composites by shear lag method

Mechanism-Based Design for High-Temperature, High-Performance Composites. Book 4

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Product

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Polarization Dependence of the Cr³⁺ R‐Line Fluorescence from Sapphire and Its Application to Crystal Orientation and Piezospectroscopic Measurement

Polarization Dependence of the Cr³⁺ R‐Line Fluorescence from Sapphire and Its Application to Crystal Orientation and Piezospectroscopic Measurement