COMPUTATIONAL MODELING OF INDENTATION - Nanoindentation with Biological Applications - page 154

(a)
(b)
Figure 6-3. Examples of mesh used in FEM: (a) Axisymmetric mesh for conical
indentation (b) Three-dimensional mesh for material with uniaxial stress.
(specimen size) has a profound effect on the resulting P - h curve; a rule
of thumb is that the specimen size should be at least 50 times larger than
the maximum indentation depth (in all directions) so as to eliminate the
boundary effect. Otherwise, the boundary effect is more prominent on
indentation stiffness compared with indentation hardness. Second, the
mesh must be sufficiently refined below the indenter. A typical plastic
zone has a radius of about two times the contact radius, and the mesh