Fracture Surface Analysis of Optical Fibers

Nanocomposite coatings for healing surface defects of glass fibers and improving interfacial adhesion

“…R m indicates the mirror radius which is about 1.2 m in this sample. A is the empirically derived constant which is 2.1 MPa×m 1/2 for silica fiber [31]. Therefore, the calculated failure stress is about 1.9 GPa, which is a fairly good agreement with above tensile test measured fiber strength.…”

Comment on: “Flexural Strength by Fractography in Modern Brittle Materials”

“…The value of the mirror constant is shown to also be approximately 1.9 MPa m 1/2 . For example, these results are in Mecholsky et al . A more recent demonstration of this independence of thickness is on page 105 (Fig.…”

“…The value of the mirror constant is shown to also be approximately 1.9 MPa m 1/2 . For example, these results are in Mecholsky et al 8,9 A more recent demonstration of this independence of thickness is on page 105 ( Fig. 1) in Freiman and Mecholsky, The Fracture of Brittle Materials, 10 which shows that optical fibers tested in tension and flexure, rectangular beams in flexure, and circular disks loaded in biaxial flexure all result in the same mirror constant for the same material over a large stress and size range.…”

“…data are fibers failed in tension. The ITT ‐ NRL and Hughes‐ NRL data are also fractured in tension. The bulk silica data are for rectangular flexure bars and the biaxial disks data are also shown.…”

Optimization of the adhesion of fiber‐optic strain sensors embedded in cement matrices; a study into long‐term fiber strength

“…The superior strength of plasma-polymerized coated optical glass fibers can be shown by fractographic analysis. Figure 14 shows a fiber broken after exposure to pore solution for almost 8 h. The fracture markings surrounding the fracture origin can be used to estimate the fiber strength (Mecholsky & al., 1979). By measurement of the radius from the appropriate origin (arrow) to the edge of the mirror-mist boundary, the stress at failure was calculated to approximately 585 MPa.…”