Discussion of Beer Bottle Defect

California failure analysis expert witness discusses bottle defects that can affect the bottle strength. In this case there are a string of bubbles in the glass that are mear the surface. There are cases where these bubbles have reached the surface and have opened. This will weaken the bottle by generating  stress risers and thinning the glass locally. Due to hoop stresses, the strength of the bottle is directly proportional to the glass thickness, there are cases where this type of defect can significantly reduce the glass thickness and the bottle strength. This is particularly important in the case of beer and sodas, where the bottle contents are under pressure (54 to 50 psi). In this case the bubbles have not surfaced, thus the effect on the bottle strength is not as severe.

California Glass Expert Discusses Bottle Failure Analysis

A California failure analysis expert has been testing the strength of beer bottles by causing them to fail from pressure overload. In all cases the origin always had a mirror region at the origin. The presence of the mirror region indicates that the crack initially grows slowly. Theoretically, the mist hackle  indicates that the crack velocity has reached its terminal velocity. As a part of bottle failure analysis, the absence of this mirror region would indicate that the bottle did not fail as a result of internal pressure. In addition, the presence of crushed glass and mechanical damage at the origin would indicate that the bottle had been hit by a hard object.