Stress intensity factor is a concept utilized in fracture mechanics theory. Note that Stress Intensity factor has nothing to do with the equivalent stress quantity, stress Intensity (Tresca Stress).
Elastic stress analysis of cracks leads to the concept of stress intensity factor K, which is employed to describe the elastic stress field surrounding the crack tip. As noted above, the motion of crack surfaces can be divided into three types, with corresponding stress fields. Hence, three stress intensity factors KI , KII , and KIII are employed to characterize the stress fields for these three modes. The dimensions of stress intensity factor K are [stress] x [length]^1/2.
The factor K depends on specimen dimensions and loading conditions. In general, K is proportional to [average stress] x [crack length]^1/2.
When K is known for a given mode (say, K1), stresses and displacements in the neighborhood of the crack
tip can be calculated.
[1] Advanced Mechanics of Materials 5th ed., Boresi and Schmidt
Also read Stress concentration factor vs Stress Intensity Factor
This page is part of The Encyclopedia of Stresses in Solids