Abstract
Wedge-indentation provides a means for overcoming some of the problems of normal indentation on curved glass surfaces. In particular, it enables testing in comparably homogenous, two-dimensional stress fields, avoiding the effects of the sharp edges of pyramidal indenters. Adjusting the wedge’s opening angle, length and orientation relative to the fiber surface enables highly reproducible studies of material deformation, surface crack initiation and effects of fiber anisotropy.
Highlights
Despite superior intrinsic material properties, commercially available glass products usually exhibit very low practical strength
The pristine silica glass fibers used for this study were provided by the Leibniz Institute of Photonic Technology (IPHT), Jena, Germany: individual glass fibers with diameters of d = 440 μm, 220 μm, and 125 μm, respectively, were drawn from a vitreous silica glass rod
We first illustrate the differences in the contact behavior between a sharp pyramidal Vickers indenter tip and a flat (Figure 2A) or a curved glass surface (Figure 2B)
Summary
Despite superior intrinsic material properties, commercially available glass products usually exhibit very low practical strength. This is due to the defect susceptibility of glass surfaces. Microscopic defects may already form during the manufacturing process (Varshneya, 2018), determining characteristic limits of practical strength for different glass products. Fiber drawn from silica or aluminosilicate glass rods (Kurkjian et al, 2003; Kurkjian et al, 2010), or tapered silica (Brambilla and Payne, 2009) have been the closest in terms of reaching the limits of theoretical (intrinsic) glass strength in praxis. Prepared glass fibers benefit from very high surface quality
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