The role of surface and volume defects in the fracture of glass under quasi-static and dynamic loadings

In this paper, the role of surface and volume defects on fracture in soda-lime glass is analyzed when samples are submitted to quasi-static or dynamic loadings. To investigate fracture, different experiments are carried out, namely, quasi-static compression of glass spheres and edge-on-impacts. The first test series aims at studying crack initiation. Different surface treatments are performed to study their influence on the failure load, from which it is concluded that initiation of cracks occurs in the vicinity of the contact surface. The second series is concerned with the examination of crack patterns under dynamic loadings with two different strikers (i.e., soft/flat and hard/perforating projectiles). Crack initiation under dynamic load histories is investigated near and far from the impact zone and it is concluded that it cannot take place within the volume, except in a very small zone close to the impact point. Conversely, initiation of damage from the surface, at a location far from the impact point, is possible and clearly present with a soft projectile.