2. Elastoplastic indentation

2.1 Hollow cavity expansion model

Historically, this model was proposed to account for fairly early experimental observations such as those shown in figure 5 . The metallurgical investigation of the plastic deformation field reveals the following facts:

• the deformation field extends far below the surface, contrary to the predictions of RPP body deformation models ;

• isodeformation curves are semicircles centered on the end of the indentor;

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