Study of carbon-fibre strain in model composites by raman spectroscopy

Lévêque, David; Auvray, M.-H.

doi:10.1016/0266-3538(96)00016-4

Cited by 29 publications

(16 citation statements)

References 3 publications

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“…on stress [454,456e459,465,468,469]. The results fulfil relatively well the predictions of micromechanical models such as Cox's (axial stress for elastic fibre and matrix, the so-called ''shearlag'' model) [413,415], Piggott's (applies after fibre/matrix decohesion and for matrix creeping) [413,417,465,473], the friction model of Kelly and Tyson [415,459,473] or that of Cook and Gordon (stress concentration in the vicinity of cracks) [465].…”

Section: In-situ Micro-raman Extensometry Of Ceramic Fibre-reinforcedsupporting

confidence: 61%

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Raman Spectroscopy of nanomaterials: How spectra relate to disorder, particle size and mechanical properties

Gouadec

Colomban

2007

Progress in Crystal Growth and Characterization of Materials

945

724

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The purpose of this review is to provide non-specialists with a basic understanding of the information micro-Raman Spectroscopy (mRS) may yield when this characterization tool is applied to nanomaterials, a generic term for describing nano-sized crystals and bulk homogeneous materials with a structural disorder at the nanoscale e typically nanoceramics, nanocomposites, glassy materials and relaxor ferroelectrics. The selected materials include advanced and ancient ceramics, semiconductors and polymers developed in the form of dots, wires, films, fibres or composites for applications in the energy, electronic and aeronauticseaerospace industries. The text is divided into five sections:

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Section: In-situ Micro-raman Extensometry Of Ceramic Fibre-reinforcedsupporting

confidence: 61%

“…22 and Ref. [458]), stress concentration factors [454,456e 458,460,462,468]), ineffective lengths 33 (IL) [458], the interfacial fracture energy G i [462] or the Coulombian friction coefficient (the proportionality factor between s radial and t ci ) [415] can be derived.…”

Section: In-situ Micro-raman Extensometry Of Ceramic Fibre-reinforcedmentioning

confidence: 99%

Raman Spectroscopy of nanomaterials: How spectra relate to disorder, particle size and mechanical properties

Gouadec

Colomban

2007

Progress in Crystal Growth and Characterization of Materials

945

724

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“…The method is already used on model Carbon/Epoxy composites [35][36][37][38][39][40] and applicability to ceramic-and metal-matrix-composites has been demonstrated recently [41][42][43][44][45][46][47] despite the high consolidation temperatures which can induce significant structural evolution (by fiber/matrix interdiffusions) and complicate the study. Even though bonds anharmonicity is usually considered as a simple perturbation to the harmonic case, it has a very significant influence on the physical behavior of materials.…”

Section: Young's Modulus and "Raman Microextensometry"mentioning

confidence: 99%

“…If so, S should eventually be proportional to [50] and others [11,36,39,40,[51][52][53][54][55][56][57][58][59][60][61][62][63][64] ), as a function of E -1/2 .…”

Section: Young's Modulus and "Raman Microextensometry"mentioning

confidence: 99%

Non-destructive mechanical characterization of SiC fibers by Raman spectroscopy

Gouadec

Colomban

2001

Journal of the European Ceramic Society

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The paper provides a comprehensive study on Raman spectroscopy versatility as a fast and non destructive tool for the prediction of the mechanical properties of SiC fibers derived from a polymeric precursor (NLM™, Hi™, Hi-S™, SA™ and Sylramic™ grades) or produced by CVD (SCS-6™ fiber), including in situ analysis in CMCs or MMCs. We show how the results of very simple spectra fitting are correlated with Young's modulus, tensile strength and microhardness. The reason why such a correlation exists, the common dependency of Raman signal and mechanical behavior to the micro/nanostructure of ceramics, is discussed. Keywords :SiC-fibers / Raman spectroscopy / Mechanical properties / Microstructure / Carbon ∂ Author to whom correspondence should be addressed Fax : 33 (0) 1 49 78 13 18 e-mail : colomban@glvt-cnrs.fr IntroductionThe reinforcement of ceramic materials by long ceramic fibers leads to low density and refractory materials, of high damage tolerance, that should be appropriate for metal alloys substitution in advanced engines (turbines) and waste treatment energy plants [1] . Ceramic fibers can also be incorporated directly in metal matrices to increase their high temperature mechanical properties [1] .SiC fibers, which are among the most stable fibers, have always been produced by the 3D reticulation of a polymeric precursor. This synthesis route leads to a high matter homogeneity and very smooth surfaces, the lack of defects explaining tensile strengths σ r as high as 3 GPa. SiC fibers have been widely studied, especially their aging [2][3][4][5][6][7] which evidenced that densification is linked to compositional changes (for instance the loss of some residual hydrogen [8] ). A peculiarity of ceramics issued from polymeric precursors is no impurities are concentrated at the grains boundaries. Abnormal grain growth is very common in the lack of such usual diffusion regulators [9] and the know-how of SiC fibers manufacturers consists in postponing the onset of SiC crystallization and grain growth, since a high correlation is anticipated with mechanical degradation. A close relationship has been evidenced, for instance, between the micro-hardness and short-range ordering in sol-gel prepared nanocrystalline oxides [10] and some authors have already pointed out fibers overall mechanical ability is governed by their microstructure [5,7,11] .The purpose of this paper is to try correlating, to the best extent possible, the tensile strength (σ r ), the Young's modulus (E) and the micro-hardness (μH) of different SiC fibers, either to Raman spectra or to "Raman Extensometry" S coefficient (measuring the straininduced shifts of Raman bands). Unlike most experimental methods intended to measure directly σ r and E, Raman analysis does not require extracting fibers from the matrix, either by mechanical grinding/crushing [12] or by chemical attack [13] . Only the most resistant fibers are extracted in the former case while fibers surface might be altered in the latter. Besides, it will always be difficult to extract...

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“…epoxy resins), which enables the tensile load to be transferred by the elastic shear deformation at interfaces (Huang and Young, 1996;Leveque and Auvray, 1996). In the composite system, Young's modulus of the interphase varies continuously in the radial direction (Liu et al, 2008;Yang and Pitchumani, 2004).…”

Section: Resultsmentioning

confidence: 99%

The effect of a graded interphase on the mechanism of stress transfer in a fiber-reinforced composite

Yin

Chen

2013

Mechanics of Materials

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a b s t r a c tBased on an improved shear-lag model, the effect of an inhomogeneous interphase on the mechanism of stress transfer in fiber-reinforced composites is investigated. The inhomogeneity of the interphase is represented by the graded feature of the Young's modulus varying according to a power law or a linear one in the radius direction, while the Poisson's ratio and thermal expansion coefficient are assumed to be constants. Considering the effects of the inhomogeneous interphase as well as the Poisson's contraction and thermal residual stress, closed-form solutions to the axial fiber stress and interfacial shear stress are obtained analytically. Comparing the case with a power law to that with a linear one, we find that the fiber stress increases significantly in the former case, while it decreases slightly in the latter one with an increasing interphase thickness. With the same external tensile load and interphase thickness, it is found that the fiber in the power law case is subjected to a larger tensile stress than that in the linear variation one. However, the interfacial shear stress is not sensitive to the interphase thickness in both cases, except that near the two ends of fiber. Under the same external load, the maximum shear stress in the interphase is much smaller in the latter than that in the former. All the phenomena can be characterized by one parameter, i.e., the average Young's modulus of interphase, and denote that an interphase with a power variation law is more effective for stress transfer while the linearly graded one is more advantageous to avoid shear failure. The results should be helpful for engineers to properly design the interphase in novel composites, e.g. a carbon-fiber reinforced epoxy one.

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Study of carbon-fibre strain in model composites by raman spectroscopy

Cited by 29 publications

References 3 publications

Raman Spectroscopy of nanomaterials: How spectra relate to disorder, particle size and mechanical properties

Raman Spectroscopy of nanomaterials: How spectra relate to disorder, particle size and mechanical properties

Non-destructive mechanical characterization of SiC fibers by Raman spectroscopy

The effect of a graded interphase on the mechanism of stress transfer in a fiber-reinforced composite

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