Fruton:
Look in an good Strength of Materials or Machine Design text book, both of which you should have on your desk. They will have some introductory material on fatigue and fracture, which appears to be where you should be starting your search. They will also have suggested further reading lists or refer to other papers and books on the subjects. No one can spoon feed you on subjects like fatigue and fracture, you have to do your own leg work.
fatigue is mostly concerned with crack initiation, and little with crack growth (since it is a much shorter phase).
damage tolerance is all about crack growth, having assumed a crack exists.
fracture is about the strength of structures with (large) cracks, ie can the structure support the loads is is supposed to with a crack x" long (and the other way 'round ... what is the highest load that a structure can support with a crack x" long).
i should've added, fracture defines the end of the crack growth phase, ie the structure needs to support a certain load, what's the largest crack size consistent with this load ?
dhengr, my question is the "relationship between fatigue and fracture", not the definition of them from a text book. I do not expect anybody to spoon feed me anything. I hope someone can find something useful from your post?
rb1957, thanks you much for your response. Its much appreciated.
In simple terms fracture is commonly the result of fatigue. Regarding fatigue of metallic materials, MIL-HDBK-5 is an excellent reference, and can be downloaded free.
Regarding fracture control of metallic components, NASA-HDBK-5010 is an excellent free reference.
You might also wish to consider beach (tide lines, wave lines, beach lines, etc.) effects.
In this case there is fatigue and then the crack extends. This happens repeatedly. When the parts sales it leaves a series of lines that are said to resemble the kind of lines of waves leave on a beach.
Example of beach (wave, etc.) marks especially prominent on the right hand part.
These are carbide router bits designed for cutting plastic on a CNC machine. They were also used in a hand held router cutting fiberglass. That is where they broke.
In my experience, when cutting tools suffer practically identical breakage it generally means a misapplication of the tool or that the wrong tool was used for the job. (Same thing - just different ways of looking at it.)
It could be a poor tool design where a weak spot was engineered or machined in.
I generally think of carbide defects as occurring randomly and look for different kinds of breakage in different parts of the tool.
Note: This is one of those concepts that seems to make sense but I am not entirely comfortable with it because I haven’t tested it much.
