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Spherical indentation of soda-lime glass and alumina

Gao-Qiu Zhu, University of Massachusetts Amherst


Spherical indentation of thick and thin glass plates were investigated numerically and experimentally. The energy release rate at the tip of a cone crack was calculated by using finite element techniques and used to investigate the applicability in thick plates of Roesler's law relating the cone crack radius to the indentation load. Indentations of thin glass specimens resting on different substrates were also studied numerically and experimentally. The stresses in the thin specimens were calculated and correlated with the observed failures. On the basis of these results, a crack initiation mechanism map was developed for glass specimens on different substrates. Spherical indentation of two types of aluminas (AD90 and AD995) carried out by Widjaja et al. (1996) produced similar cracking patterns to those observed in glass specimens which consist of ring, cone and radial cracks. Using ABAQUS we calculated the stress distributions for 2 mm thick alumina specimens (AD90 and AD995) resting on a 3 mm thick steel substrate under spherical indentation of a 2 mm radius sphere. It was found that at a load of 1800 N and 2000 N for a specimen of AD90 and AD995 respectively, the maximum hoop stress $\sigma\sb{\theta}$ on the bottom surface of the alumina specimen reaches approximately the fracture strength $\sigma\sb{f} \approx 260$ MPa. This maximum hoop stress is believed to be responsible for the initiation of radial cracking in the alumina specimens as observed by Widjaja et al. (1996). Finite element analysis was also carried out on the spherical indentation of sandwich specimens. The stress distributions were obtained on the top surface and interface of the sandwich specimen. The energy release rates of a debonding crack on the interface of the sandwich specimen were calculated.

Subject Area

Civil engineering|Mechanical engineering

Recommended Citation

Zhu, Gao-Qiu, "Spherical indentation of soda-lime glass and alumina" (1997). Doctoral Dissertations Available from Proquest. AAI9721501.