Observation and numerical simulation of an elastic-plastic solid loaded by a spherical indenter

The observation and finite element simulation of Ti-6Al-4V loaded by a spherical indenter were compared. The contact radius at the maximum load was 40% of the indenter radius, which resulted in a high degree of plasticity induced beneath the indenter. The spherical impression profile predicted by the simulation was in agreement with that of the observation. The local curvature of the spherical impression was shown to vary with radial distance. The overall curvature change with radial distance was more distinctive in the presence of static friction. Due to the large plastic zone in the material, neither the Field-Swain nor the Oliver-Pharr method was able to predict the elastic recovery depths in the center of indentation and at the perimeter of contact. The ratio of the two depths predicted by the latter method, however, may be used to verify the applicability of the method itself in determining the elastic modulus of a ductile material.