Analysis of the Single‐Fiber Pullout Test Using Raman Spectroscopy: Part III, Pullout of Nicalon Fibers from a Pyrex Matrix

Abstract

Single‐fiber pullout specimens consisting of Nicalon fibers and a Pyrex‐glass matrix were fabricated using a specially designed, simple mold. Raman spectroscopy was used to map the distribution of fiber strain within the glass matrix following deformation of the fiber section in air, and the results were compared with those predicted by theoretical analyses. It was demonstrated that the behavior also could be modeled using a partial debonding theory and that the force balance equilibrium allowed the variation of inter‐facial shear stress along the interface to be derived. The partial debonding theory showed that debonding occurred at an interfacial shear stress of 60 ± 20 MPa and that the friction shear stress following debonding was 23 ± 8 MPa for the specimen investigated. Furthermore, it was shown that the fracture toughness of the fiber‐matrix interface was 1.8 ± 0.6 J·m–2.

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

“…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].…”

“…Given the much higher Young's modulus of such matrices with respect to resins, Ineffective Lengths (ILs) are small enough (a few micrometers only instead of hundreds [458]) for a cross-section analysis to give results close to those obtained with longitudinal probing [90,389,392,474,475]. Yang and Young [473,476,477] studied 3 f (l) in model single fibre NLM/pyrex and NLM/SiC [478] composites. Bollet et al [479] measured the influence of micro-cracking in SiC/glasseceramic composites.…”

Analysis of Strain and Stress in Ceramic, Polymer and Metal Matrix Composites by Raman Spectroscopy

“…Raman spectroscopy micron scale resolution makes it possible to assess the so called ªenvironment effectº on stress in composites (fibre volume fraction and/or neighbouring damaged fibre, [38±42] cracks/holes, [44] sizing [45] or water absorption). [46] Experimental results are in reasonable agreement with the micro-mechanical models of Cox (the so-called ªshear-lagº model measuring axial stress in the elastic domain), [2,12] Piggott (after fibre/matrix debonding), [45,47,48] Kelly-Tyson (friction) [35,45,48] or Cook and Gordon (stress around a crack). [44] The ability of measuring the strain profile along a fibre adjacent to a broken one inside a composite gives a direct measure of the stress concentration factor for the intact fibre.…”

“…[42] The cross section analysis then gives a result close to the ªlongitudinalº one. [13] Model ªsingle fibreº NLM TM /Pyrex TM , [48,54,55] NLM TM /SiC, [56] SiC Tyranno TM /glassy matrix, [57] C/C, [58] C Graphil TM /mullite, NLM TM /mullite [13] or Hi-Nicalon TM /mullite, [53] Hi TM (BN/SiC)/celsian and SCS-6 Textron TM /Ti6242 [52] composites were studied.…”

Non-destructive mechanical characterization of SiC fibers by Raman spectroscopy

“…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 .…”