Fatigue is usually associated with tensile stresses.
Engineering knowledge of compressive fatigue is very limited. Compression stresses do not cause cracks, but plastic compressive strain can cause tension stresses when the load is returned to zero and the resulting tension stress causes cracks.
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But R -> – infinity for pure compression stress and with max stress->0
MIL-HBBK-5J S/N curves are typically given for a family of R values starting at a lower limit of R=-1.
So MIL-HBBK-5J is not useful for pure compression.
Compressive residual stresses can be introduced in the surface by shot peening to increase fatigue life.
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