Weibull statistical analysis of the mechanical strength of a glass eroded by sand blasting

In Saharian regions, the erosion of glass by sand particles during sandstor ms is a regular phenomenon. The progressive loss of matter on surface affec ts both the optical transmission and mechanical strength. In this work, the influence of sand impacts on glass strength was simulated in laboratory. W e used Weibull distribution function to characterize statistically the vari ation of the mechanical strength of a soda-lime glass in the as received st ate and eroded by sand blasting during 30 and 60 min. From the failure prob abilities distributions, we notice an important drop in strength values (ab out 13%) after 30 min and a tendency to level out with a much reduced dispe rsion after 60 min. The Weibull plots for the as-received state and for the 30 min eroded state present curves with a knee. They were considered as bi modal forms (two straigth lines) denoting the presence of two kinds of defe cts that control strength. The Weibull plot for the 60 mins eroded state sa mple presents one straight line (unimodal form) that indicates the predomin ance of erosion defects. From micrographical observations on eroded specime n, we observed a tendency toward a damaging homogeneity of the surfaces exp osed to sand blasting. This explains the uniformity of the strength values obtained after I h of sand blasting. (C) 1999 Elsevier Science Ltd. All rig hts reserved.