Impact fracture in zone- and full-tempered glass was studied by high speed photography using a Cranz-Schardin type camera, and the following conclusions were reached: The maximum crack velocities of tempered glass were 1.500 x 103 m/s and 1.486 x 103 m/s for the tempering strengths of 172 MPa and 123 MPa, respectively. The result indicated weak dependence of the maximum velocity on the tempering strength. High-speed photoelastic color photography was successfully performed using a tint plate in the photoelastic optical setup. Change of dynamic stress distribution around the crack tip could be well visualized by the change in color. Fast cracks even with the terminal velocity can vertically turn quickly with a small curvature of 2 mm. About 70 % of the total secondary cracks developed within 1 msec after initiation of the impact crack. Caustic images were observed for thick tempered specimens and it was shown that the dynamic stress intensity factor of a crack with the terminal velocity decreases by 50 % recovered at a propagation distance of less than 20 mm.
Fast fracture in tempered glass
Time Dependent Mechanical Response of Engineering Ceramics, Yamazaki International Symposium, 2 ; 9-17
1999
9 Seiten, 12 Bilder, 2 Tabellen, 15 Quellen
Conference paper
English
vorgespanntes Glas , Hochgeschwindigkeitsphotographie , Hochgeschwindigkeitskamera , Schlagprüfung , Bruchmechanik , bruchmechanische Prüfung , Rissausbreitung , Ausbreitungsgeschwindigkeit , Farbphotographie , mechanische Spannungsverteilung , Rissspitze , Spannungsoptik , Risswachstum , Kraftfahrzeug , Verglasung (Produkt) , Windschutzscheibe