Fibers strength determination

Relative strength determination by solution measurement is difficult in the case of vat and sulfur dyes and leads to unreflable results in cases where some of the dye in the commercial product has no affinity for the fiber such as for certain direct and fiber-reactive dyes. 

The fiber strength is determined for a particular cramped length (for example, for the 10 mm base) and the specimen is tested under tension (bending) at two P values. One then solves the set of simultaneous equations ... 

The effect of the iodine biocide on the aramid fibers was determined by using fibers taken from a permeator previously exposed to this agent during tests. It was found that these fibers retained most of their physical strength, eind the resulting damage should not significantly alter the life of the membrcine. 

Manor, A. and Clough, R.B. (1992), In-situ determination of fiber strength and segment length in composites by means of acoustic emission. Composites Sci. Technol. 45, 73-81. 

In an investigation of factors affecting strength of synthetic fibers a modification was made in the preparation of the material and a series of separate preparations of fiber was made in pairs, one of the regular and one of the modified material and a number of properties of the resulting fibers were determined. The results for each... 

Ti5Si3 fibers was estimated to 2530 MPa. This value is higher than the fiber strength reported in the paper of Crossman et al. [24], The estimated stress is of the order of the strength of titanium silicide whiskers prepared by chemical vapor deposition. However, it should be noted that it is very difficult to determine the exact flow stress and tensile strength at room and somewhat higher temperatures because of the brittle behaviour of the Ti5Si3 fibers. 

The stability of the interface and matrix morphology may not be as critical for defense applications, where the service time of the ceramic component, especially at peak temperatures, is relatively short. Uncoated fibers in a porous matrix, however, may subject the fibers to corrosive species in the operating environment that could degrade fiber strength. These composite systems must be tested in their service environments to determine if the absence of a fiber coating accelerates the degradation of fiber strength. 

Figure 5.44 Profile of the distribution of nitrogen in a cross-section of Toray T-300 carbon fiber as determined by Electron Energy Loss Spectroscopy (EELS). The position of the area of the surface is measured by the distance R/D, where D is the apparent width of the section in the microscopy image and R is the distance between the edge of the fiber and the point of measure. Source Reprinted with permission from Serin V, Fourmeaux R, Kihn Y, Sevely J, Guigon M, Nitrogen distribution in high tensile strength carbon fibres, Carbon, 28(4), 573-578, 1990. Copyright 1990, Elsevier.

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