Statistical analysis of threshold load for radial crack nucleation by Vickers indentation in commercial soda-lime silica glass

The threshold load for nucleation of primary radial cracks in commercial soda-lime silica glass was investigated at room temperature by using Vickers indentation. The Weibull statistics with three-parameters was employed to analyze the number of cracks nucleated around each indentation as function of the applied load. The used probability estimator was (n − 0.5)/N, where n is the total number of radial cracks nucleated at a specific load and N is the total number of possible cracks. The minimum applied load for radial crack nucleation that best fitted the experimental data was equal to 180 mN. Comparison between experimental data distribution and the binomial distribution was also performed. The results were interpreted according to the fracture mechanics models for sub-threshold indentation flaws of Lathabai et al. and for crack initiation in elastic/plastic indentation of Lawn and Marshall.