Stress concentration, especially at sharp corners, is a well known phenomenon. During the second world war, the US manufactured transport ships in an assembly l

Stress concentration, especially at sharp corners, is a well known phenomenon. During the second world war, the US manufactured transport ships in an assembly line fashion. The were launching these ships at rates of more than one per week. A lot of them had the same design flaw: the cargo hatch corners were not properly rounded off. This made them starting points for cracks in the hull. Amd once a crack is started, it continues to extend relentlessly under stress. As the story goes, a few of these ships were lost because the cracks grew so long that the hulls broke and sank.