Fibers fractography

Fiber Fractography and Morphology. Fibers broken in tensile tests were examined in the scanning electron microscope to gain a better understanding of their failure mechanism. Such insight can be used to guide the development of consolidants that prevent such failures. 

SEM is a valuable tool for carbon fiber fractography, with no sample preparation required, but polished sections exhibit no structural information and it is necessary to etch the surface. For this purpose, Manders [13] employed electrolytic etching. 

Textile fiber fractography was initially developed at UMIST (University of Manchester Institute of Science and Technology), especially by Hearle. Fiber fractography and the classes of fracture were reviewed by Hearle and Simmens [15] and further defined later [29, 30]. These classes are shown in Table 5.1 with examples and appropriate references. The mechanism of fiber failure can be determined by fractography studies (Section 4.8.1) in the SEM. Typically, fibers broken during a standard physical test, such as... 

Friedrich, K. and Karger-Kocsis, J. (1989). Unfilled and short fiber reinforced semi-crystalline thermoplastics. In Fractography and Failure Mechanisms of Polymers and Composites, (A.C. Roulin-Moloney ed.), Elsevier Appl. Science, London, pp. 437-494. 

BRESEE AND GOODYEAR Fractography of Historic Silk Fibers... 

The evaluations of short fiber reinforced composites for fracture behavior includes studies with respect to material parameters such as the fiber content [42,103,120], fiber length and orientation [69,97,103,115], and fiber bundling [115.120] testing conditions such as the temperature [24,42,121,122] and the loading rate [121,123,124] and fractography [42,43,103,123], The influence of some of these parameters, e.g fiber content, rate of loading, and the test temperature on the fracture toughness of composites can be presented in the form of property maps [125,126],... 

Table 4 Main features of the tensile behaviour of minicomposites determined from the force-deformation curves (Fj is proportional limit) and from SEM fractography (fiber pull out length Ip, crack spacing distance at saturation d,).

A study of the hydrogenation process in vapor grown carbon fibers using modified SEM fractography was undertaken [14]. 

Keywords Fractography Morphology and properties Plant fibers Statistical evaluation Weibull analysis... 

Chandan, H.C., Parker, R.D. and Kalish, D. (1994) Practography of optical fibers. In Fractography of Glass. 

The objective of quantitative fractography is the quantitative description of the fracture surface in terms of parameters such as roughness, fiber orientation, phase content, and particle size distribution. Therefore different characteristics such as shape (area), size (eg length, diameter), anisotropy (orientation, direction), and distribution (spacing) of material components or topographical details are being evaluated. 

SE images of a matched pair of tensile failed PET fibers are shown in Fig. 4.30. A classical slow fracture zone, or mirror, is seen adjacent to the locus of failure. A typical ridged or hackle morphology is exhibited as the crack propagates and accelerates away from the failure locus. In this study, an inorganic residue from the polymer process was shown to be the cause of failure [295]. The value of such a fractography is that... 

---