Wine Glass Failure Analysis

Glass failure expert witness performs a root cause failure analysis on a failed wine glass. Failure analysis revealed that the failure initiated on the inside edge at the bead on the top. The top left photograph shows the re-assembled glass; the arrow indicates the crack starting point. The upper right photograph is a 40X photomicrograph of the fracture surface; the fracture initiation point is indicated by the arrow. The crack formed at the top bead on the interior of the glass. The asymetry of the Wallner lines demonstrates that the crack progressed under bending stresses. Since there are no signs of impact, squeezing the glass ss must have been the cause of failure.