Figure 1. Operation of the Abrio system
Figure 2. Cone indent in glass
Figure 3. Retardation and azimuth in soda-lime-silica glass perpendicular to the load direction.
Figure 4. Retardation and azimuth in silica glass perpendicular to the load drection.
Figure 5. Retardation in silica glass parallel to the load direction.
Figure 6. Azimuth in silica glass parallel to the load direction.
From these images, it can be seen that there are substantial differences in the magnitude and distribution of the stress birefringence due to indentation in these two glasses ( as expected, see Arora et al. JNCS 31 415-428, 1979). This is also to be expected based on the portions of flow due to shear and compaction in the two glasses (see Yoshida et al, J. Mater. Res, 20 (12) 3404-3412, 2005), as well as earlier work of Peters, Hagan and others. Detailed calculation of the 3D stresses are in progress and will be presented soon.
It is clear that an understanding of such indentation processes is critical to the development of more robust glasses as well to the development of appropriate scoring cracks for the 'thermal cutting' of substrate glasses used for liquid crystal displays. Such quantitative work has not been done to date. The availability of the CRI Abrio system as well as the analyses of Prof. H. Aben and A. Errapart at the Institute of Cybernetics at Tallinn University of Technology in Estonia (see 'links') have made this work possible.