What is critical in stress intensity?
Stress intensity is related to product of stress and flaw size for materials. If stress is increased to critical, this results in catastrophic failure. The critical stress intensity factor KIc is a property of the material.
KIc = Strength x sqrt(flaw) x geometry factor
The stress concentration factor is a number that raises stress locally due to factors such as holes and change in cross section. In the latter case, the sharper the radius at he cross section change, the higher the stress concentration. Typically, these factors range from 1 to 3 and sometimes more. Stress intensity factor is a bit different; it is an inherent property of the material that is tested and defined for cracks or flaws…