Which is NOT a CIF susceptibility factor?

Which is NOT a CIF susceptibility factor?

• A. High tensile stresses
• B. High constraints
• C. Planar discontinuity normal to primary stresses
• D. Corrosion

Answer: (D)

Focusing on what promotes crack initiation under cyclic loading, CIF susceptibility factors are the mechanical conditions that make a flaw start and propagate. High tensile stresses increase the energy driving crack opening and growth under repeated loading. High constraints prevent the material from redistributing stress around a flaw, which raises the local stress intensity and makes initiation more likely. A planar discontinuity oriented normal to the applied primary stresses concentrates those stresses in the most loaded plane, further promoting initiation. Corrosion, while it can contribute to deterioration and, in some cases, corrosion-fatigue, is not considered a CIF susceptibility factor because CIF deals with the purely mechanical initiation aspects under cyclic load, independent of environmental attack. In practice, corrosion can exacerbate damage through separate mechanisms, but the factors that govern CIF are the stress state and flaw geometry described above.

Focusing on what promotes crack initiation under cyclic loading, CIF susceptibility factors are the mechanical conditions that make a flaw start and propagate. High tensile stresses increase the energy driving crack opening and growth under repeated loading. High constraints prevent the material from redistributing stress around a flaw, which raises the local stress intensity and makes initiation more likely. A planar discontinuity oriented normal to the applied primary stresses concentrates those stresses in the most loaded plane, further promoting initiation. Corrosion, while it can contribute to deterioration and, in some cases, corrosion-fatigue, is not considered a CIF susceptibility factor because CIF deals with the purely mechanical initiation aspects under cyclic load, independent of environmental attack. In practice, corrosion can exacerbate damage through separate mechanisms, but the factors that govern CIF are the stress state and flaw geometry described above.