Determination Of Residual Stresses Utilizing The Variation Of Hardness At Elastic Plastic Indentation

Material hardness is independent of residual stresses at predominantly plastic deformation in the region of contact between an indenter and the material. This is an important fact, as such a situation is relevant for most metals and alloys. It has, however, been established that when elastic and plastic deformations are of equal magnitude, this independence is lost. This fact complicates residual stress determination in such a situation, pertinent to materials such as ceramics and polymers, but it also provides additional important information for performing such a task in an accurate manner. Presently, a relevant formula for taking advantage of this information is presented. The formula is based on previous results pertinent to indentation analyses of stress-free materials. The predictions are compared to finite element results from previous studies describing cone indentation of materials with residual stresses. The analysis is restricted to classical elastoplasticity.