Yes, beach marks are well known in structural failures and there is a good bit of info online.
An initial flaw can often be the starting point but it takes a series of stresses in a particular direction to cause those marks. Not a one time event.
Striations are a similar type of mark but very hard to impossible to see without magnification. Think of a shaft being bent in rotation due to misalignment or just bending something back and forth until failure. The discoloration is due to moisture getting into the crack after it has started but long enough before the complete failure so it has time to cause the corrosion that is the color change.
Sharp edges, section changes, etc., are very bad if you want to eliminate likely starting points for cracks and repetitive bending in a direction that highlights those flaws makes thing break.
I know, calling a sharp edge a flaw in a knife sounds like blasphemy when talking about knives but that's what it is from an engineering standpoint.
An initial flaw can often be the starting point but it takes a series of stresses in a particular direction to cause those marks. Not a one time event.
Striations are a similar type of mark but very hard to impossible to see without magnification. Think of a shaft being bent in rotation due to misalignment or just bending something back and forth until failure. The discoloration is due to moisture getting into the crack after it has started but long enough before the complete failure so it has time to cause the corrosion that is the color change.
Sharp edges, section changes, etc., are very bad if you want to eliminate likely starting points for cracks and repetitive bending in a direction that highlights those flaws makes thing break.
I know, calling a sharp edge a flaw in a knife sounds like blasphemy when talking about knives but that's what it is from an engineering standpoint.
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