Ring-on-Ring Tests and the Modeling of Cladding Glass Strength by the Weibull Distribution

Summary

Although ring-on-ring test results have been used in the past to obtain information on the strength of glass, no methodology has so far been developed explicitly relating such results to the load capacity of cladding glass panels. The purpose of this paper is to propose such a methodololgy. Evidence is presented which strongly suggests that the probability distribution of the load capacity of cladding glass panels whose failure is due to surface flaws can be estimated reliably on the basis of results of ring-on-ring tests used in conjuction with: (a) numerical methods for the analysis of stresses in plates, and (b) information on the elastic and fracture mechanics behavior of glass currently available or that can be obtained routinely. Two interesting findings are noted. First, owing to the way in which results of ring-on-ring tests are utilized, the relatively large variabilities typical of fracture mechanics parameters as well as the uncertainties with respect to the shapes of surface flaws have a minor effect on the estimation of load capacities. Second, two-parameter Weibull distributions, previously used in the literature to model the strength of glass and the load capacity of cladding panels,are not consistent with experimental results. On the other hand, three-parameter Weibull distributions model the observed glass behavior credibly.