Understanding Material Breakage: Fractures, Fatigue, and More

[anime9999]

Hi and thank you in advance.

I want to understand how do fractures/breaks/fatigues occur in general.

I remember a proverb saying that when a farmer breaks a rock after 100 hits using his axe, it is not the 100th hit that breaks the rock, but it is all of the 100 hits.

How material break? what happens when you hit a metal with something and it doesn't break? where does the energy go? does every hit means a degradation in the structure (although not visible)?

For example, if I gently hit my tooth with a spoon, do I still impact the structure of my tooth (although my tooth doesn't break?)

I hope you understand my question.
Thank you and best regards.

 

[Bandit127]

You should look up fatigue. Find an article with an S-N curve if you can.

 

[AppleBite]

What you are describing is an entire academic field called Fracture Mechanics, covered by many engineering courses. The field is vast, and the process of fracture will depend on the material, loading and test conditions, etc.

Start with this link, and there are also numerous books and papers on the subject depending on what materials you are interested in:

http://en.wikipedia.org/wiki/Fracture_mechanics

 

[anime9999]

Thank you. I will look up fatigue and fracture mechanics.
I see this is indeed a very complex subject.