Equation 18 · Part 1 · Why Materials Fail: Fracture, Flaws and the Inspection Interval
Symbol K
What this part means
K is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
Its job in the formula
K is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
Full expression→Symbol K→Article meaning
The passage around this formula
Two caveats belong here rather than in a footnote. The linear-elastic parameter K is only meaningful under small-scale yielding, where the plastic zone at the tip is small relative to the crack and the remaining ligament. When it is not — thin sections, tough alloys, high temperatures — elastic-plastic parameters such as the J-integral or crack-tip opening displacement are required instead. And is measured under a standardised constraint condition; a thin plate of the same alloy will exhibit a higher apparent toughness because plane-stress conditions permit more plastic work. Toughness quoted without its measurement conditions is close to meaningless.
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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