Experimental investigation into the fragment size of tempered glass

Abstract

This work presents the relation between the fragment density and the permanent residual stress in fragmented tempered glasses of various thicknesses. Therefore, fracture tests were carried out on tempered glass plates and the fragments in observation fields of 50 mm × 50 mm were counted. The average fragment density in the observation fields was set in correlation with the average measured residual stress of each specimen. Furthermore, the average particle weight of 130 particles per specimen chosen by random was determined. The relation between the average particle weight and the measured residual stress is given. The volume and the base surface as well as the radius of the particles are calculated assuming cylindrical fragments with approximately unchanged thicknesses. The relation between the residual stress and the particle base surface of regular polygonal shapes n= 3 –8 edges in addition to the cylindrical fragment (n→ ∞) is also determined. The glass used for the fracture tests was commercial soda-lime-silica glass with three different thicknesses 4, 8 and 12 mm. The results in this work are a basis for the establishment of a theoretical model to predict macro-scale fracture patterns from elastic strain energy in tempered glass.