Dissemination of IT for the Promotion of Materials Science (DoITPoMS)

DoITPoMS Teaching & Learning Packages Brittle Fracture Why bother if they are the same?
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Why bother if they are the same?

K is useful because stress intensity factors, like stresses, are additive. Irwin showed that any loading state could be broken down into 3 different types of loading that he called modes, I, II and III:

Diagram of 3 different types of loading

To get the total K, we just sum the contribution from each of the three modes.

This is much more difficult to do with energies, where we would have to think about interaction terms.