On non-destructive residual stress measurement in glass panels/Jaakpingete mittepurustav maaramine klaaspaneelides

A portable scattered light polariscope SCALP has been developed, which permits measurement of the residual stress profile through the thickness of glass panels. At a glass factory strength assessment of glass panels of different thermal treatment was carried out using both residual stress measurement with SCALP and the traditional four-point bending tests. Linear correlation between the residual surface stress and the bending strength was observed. At another glass factory residual stress in glass panels was measured before performing the traditional fragmentation test. The results of the fragmentation test were extremely scattered and had almost no correlation with the values of the residual stress. It is concluded that sufficiently reliable assessment of the strength of glass panels is obtained by measuring the residual stress at the surface. Key words: glass, residual stress, photoelastic measurements, quality control. On valja tootatud portatiivne hajunud valguse meetodi polariskoop SCALP jaakpingete profiili mootmiseks klaaspaneelides. Erineva termilise tootlusega klaaspaneelide tugevuse hindamiseks moodeti uhes klaasitehases klaaspaneelide jaakpinged, mille jarel maarati paneelide tugevus nelja punkti paindekatsel. Seos jaakpingete ja tugevuse vahel osutus lineaarseks. Uhes teises klaasitehases vorreldi eelnevalt moodetud jaakpingeid klaaspaneelides fragmenteerimiskatse tulemustega, mis olid vaga hajuvad ja jaakpingetest praktiliselt soltumatud. Toost jareldub, et koige usaldusvaarsem on hinnata klaaspaneelide tugevust klaasi pinnal moodetud jaakpingete pohjal.