The strength of glass, a nontransparent value

The tendency in modern architecture to use glass structurally means that we need to know the engineering properties of glass accurately. The most important of these is the failure strength of glass in bending. Although much work on this has been done and published there are still many questions. These deal mainly with the correct statistical description of the strength of glass, specifically the question whether the Weibull distribution is a satisfactory descriptor. Secondly there is the procedure for determining the design stress of glass. Experiments have been conducted using large series of specimens treated in several ways. The results show the treatments influence the statistical distribution. Water can result in linear Weibull distributions while other types of glass almost always show bilinear Weibull distributions. A model is proposed which explains the differences between the test series.