Consider the example problem in Section 13.2.3.1 where a planar surface with a residual compressive stress is subjected to cyclic normal indentation without friction. If the equi-biaxial residual compressive stresses at the indented surface were to be
is the yield strength of the material, calculate how much higher normal indentation force P can be applied without plastically yielding the surface as compared to the case where the surface has no residual compressive stresses.