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Equation 9 · Part 5 · Why Materials Fail: Fracture, Flaws and the Inspection Interval

Symbol a

σf=2Eγsπa.\sigma_f = \sqrt{\frac{2E\gamma_s}{\pi a}}.
aa

What this part means

a is an input to the expression that computes the quantity on the left.

Its job in the formula

a is an input to the expression that computes the quantity on the left.

The passage around this formula

Griffith’s criterion is an accounting statement. Extending a crack by a small increment releases stored elastic strain energy from the material that unloads around the new crack faces, and consumes energy in creating those faces. If the release exceeds the cost, extension is spontaneous and the crack runs. For a through-thickness crack of half-length a in…

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Learn the underlying idea

A variable is a named place for a value. Its letter is a local label: x can mean position in one formula and a data point in another.

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