The authors should be commended for tackling a subject that is in much need of additional experimental investigations. It is very difficult to make these measurements, and the authors have made a very significant contribution to the field by doing so. There are several issues in this work, however, that need to be addressed before a direct comparison between experimental and numerical results can be made.

First, the method outlined for measuring the real area of contact actually measures the deformed profile of the surface after it is unloaded. Due to some elastic recovery (even in the fully plastic regime), this profile will be different than the profile during contact. An alternative might be to compare this unloaded profile to the results of (1,2) (Refs. 21 and 22 of the authors' paper). It is known that the...

1.
Jackson
,
R. L.
,
Chusoipin
,
I.
, and
Green
,
I.
, “
A Finite Element Study of the Residual Stress and Strain Formation in Spherical Contacts
,”
ASME J. Tribol.
0742-4787, 2005,
127
(
3
), pp.
484
493
.
2.
Etsion
,
I.
,
Kligerman
,
Y.
, and
Kadin
,
Y.
, “
Unloading of an Elastic-Plastic Loaded Spherical Contact
,”
Int. J. Solids Struct.
0020-7683, 2005,
42
(
13
), pp.
3716
3729
.
3.
Kogut
,
L.
, and
Komvoppoulos
,
K.
, “
Analysis of Spherical Indentation Cycle of Elastic-Perfectly Plastic Solids
,”
J. Mater. Res.
0884-2914, 2004,
19
, pp.
3641
3653
.
You do not currently have access to this content.