PSI - Issue 13

Stefan Reich et al. / Procedia Structural Integrity 13 (2018) 28–33 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

33

6

Because of the large surface energy coefficients  s in Table 2, a detailed analysis is necessary what ratio of the potential energy of the steel ball is really used for fracture. A detailed answer for this needs comprehensive investigations that were not part of the research. Only preliminary testing was done to investigate the damping influence of the gasket to estimate its effect on the result. A first comparison between glass support with- and without gasket showed an approximately 50% difference in glass strains either at drop height of 6.75 cm or 16.75 cm.

4. Discussion and Conclusion

With the experiences of the testing the following conclusions are made:  Former papers describe the use of a static testing technique to determine the applied force and the crack length and need complicated small size specimens.  At ball drop tests a linear relation between drop height and crack length was determined at average values.  The surface energy coefficients  s are constant at different drop heights but 10 to 20 times larger than the values determined with static techniques and show that the majority of the potential energy of the impactor is not used for crack creation.  Standard ball drop test build-ups with gaskets use a significant part of the potential energy of the impactor for damping.  Especially at large drop heights the amount of small glass fragments (powder) possess a surface that is not considered in the measured crack area and needs to be determined more exactly.  Further energy relevant issues are not known, e.g. the crack reaches the edge, sound at glass failure, elastic behaviour of pane and impactor.  Ball drop test is still not appropriate for determining the fracture energy of glass, as either the crack area determination or the crack creation energy are not determinable with the used testing set-up. It is necessary to know, what percentage of potential energy of the impactor is used for crack creation. 5. Acknowledgement Special thanks go to Thiele Glas Werk GmbH, Wermsdorf, Germany who sponsored all glass specimens for testing. Griffith, A.A., 1921. The phenomena of rupture and flow in solids. Philosophical Transactions of the Royal Society London Series A. (221), pp. 163-198. Reich, S.; Weller, B.; Dietrich, N.; Pfefferkorn, S., 2012. Energetic approach of elastic strain energy of thermally tempered glass. Challenging Glass Conference 3; Delft. pp. 509-521. Kerkhof, F., 1970. Bruchvorgänge in Gläsern. Frankfurt am Main: Verlag der deutschen glastechnischen Gesellschaft,. Acloque, P., 1975. Déformation et rupture des verres. Ann Mines. 2, pp. 57-66. Nielsen, J. H.; Olesen, J. F.; Stang, H., 2009. The Fracture of Tempered Soda-Lime-Silica Glass. Experimental Mechanics, Bd. 49, 6, pp. 855-870. Petzold, A.; Marusch, H.; Schramm, B., 1990. Der Baustoff Glas. Berlin : Verlag für Bauwesen,. pp. 35. Shand, E. B., 1961. Correlation of Strength of Glass with Fracture flaws of Measured Size. J. Am. Ceram. Soc., Bd. 44(9), pp. 451-55. Gulati, S. T., 1997. Frangibility of Tempered Soda-Lime Glass Sheet, Glass Processing Days. Tampere: pp. 227-231, Conference proceedings. Roesler, F. C., 1956. Brittle Fractures near Equilibrium. Proc. Phys. Soc., Bd. 69B, pp. 981-92. Wiederhorn, S. M., 1969. Fracture Surface Energy of Glass. Journal of the America. Ceram. Soc. February, pp. 99-105. Shutov, A. I., Popov, P. B. und Bubeev, A. B., 1998. Prediction of the character of tempered glass fracture. Glass and Ceramics. 55, Nakayama, J, 1965. Direct measurement of fracture energies of brittle heterogeneous materials. Journal of the American Ceramic Society, Bd. 48.11, pp. 583-587. Mecholsky, J. J.; Rice, R. W.; Freiman, S. W., 1974. Prediction of Fracture Energy and Flaw Size in Glasses from Measurements of Mirror Size. Journal of the American Ceramic Society, Bd. 57, 10, pp. 440-443. Clif, C. J., 1957. Fracture of glass under various liquids and gases. Journal of the Society of Glass Technology. Bd. 41, pp. 157-167. Linger, K. R.; Holloway, D. G., 1968. The Fracture Energy of Glass. Philosophical Magazine, Bd. 18, 156. Berdenikov, W. P., 1933. Measurement of Surface Tension of Solids. Soviet Phys. Z.S., Bd. 4, pp. 397-419. Proctor, B. A.; Whitney, I.; Johnson, J. W., 1967. The strength of fused silica. Proc. R. Soc. Lond. Bd. 297, pp. 534-557. Davidge, R. W.; Tappin, G., 1968. The Effective Surface Energy of Brittle Materials. Journal of Materials Science. Bd. 3, pp. 165-173. Takahashi, K., 1999. Fast Fracture in Tempered Glass. Key Engineering Materials Vanapalli, M.R.S., 2014. Correlation between impact energy and surface energy at annealed glass. Technische Universität Dresden, DIN 52338, 1985. Test methods for flat glass in buildings: ball drop test for laminated glass. 6. References