Plastic strain distribution underneath a Vickers Indenter: Role of yield strength and work hardening exponent

Study of the concept of representative strain and constraint factor introduced by Vickers indentation

“…For Mata et al (2002) From an experimental investigation of the surface and subsurface strain hardening around Vickers indentations in annealed copper, it was determined that the maximum plastic strain occurs in a subsurface region close to the indentation tip where the estimated plastic natural strain is in the range from 0.25 to 0.36 (Chaudhri, 1998). Srikant et al (2006) found similar values of maximum strain for similar experimental conditions (maximum plastic strain in the range between 0.22 and 0.31). Chaudhri (1998) suggest that the equivalent strain associated with a relatively large Vickers indentation should be 0.25-0.36 for annealed metals having a power law uniaxial stress vs strain relationship.…”

The Effect of the Vertex Angles of Wedged Indenters on Deformation during Nanoindentation

“…The dislocation zones in nanoindentation with both indenters of 60 • and 70 • extend deeply inside the bulk material, but the width would not exceed the contact width, which is defined as the width of the segment where indenter is in contact with the material. This phenomenon also agrees with many indentation experiments [33,34]. The width of the zone where partial dislocations move in the loading process with the indenter of 70 • is wider than that in loading process of 60 • , and the amount of dislocations that remain in the material after retraction with the indenter of 70 • is larger than that with the indenter of 60 • .…”

Role of indenter angle on the plastic deformation underneath a sharp indenter and on representative strains: An experimental and numerical study

“…One of the possible reasons for this paucity could be the fact that it is difficult to conduct systematic experiments that give insights into the subsurface plasticity during indentation. While the experiments of Srikant et al [37] clearly demonstrate that the plastic strain fields underneath a sharp indenter are complex in nature and sensitive to both n and Y, their work suffers from the fact that n values of the Al alloy they have used are relatively low. Keeping this in view, we have chosen annealed Cu, which work hardens considerably, with the following objectives: (i) to systematically evaluate the plastic strain fields underneath a cone indenter, so as to examine the influence of a on strain field distribution; (ii) to experimentally assess the representative strain as a function of a and use these for critical evaluation of available analytical estimates; (iii) to conduct FE simulations, which match the experimental conditions one-to-one, and see if they describe accurately the plastic distributions underneath the indenter.…”

“…(iii) e r of 0.08, as proposed by Tabor [36], does not have any physical significance. Recently Srikant et al [37] have examined the explicit influence of Y and n on plastic strain distributions underneath the Vickers indent in an Al alloy that was aged to different levels. Their results show that for similar values of n, higher Y leads to a smaller deformation field, whereas a higher n, at the same Y, leads to a shallower deformation field.…”