ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

a) b)
c) d)
Figure 7 Validation: a) D=2mm, load=0.19N µd=0.9; b) D=2mm, load=0.5N µd=0.7; c) D=5mm, load=0.19N µd=1.1; d) D=5mm,
load=0.5N µd=0.8
6. SUMMARY
In the previous work the skin friction and deformation behaviour has been measured in-plane and perpendicular to sliding
direction during in vivo reciprocating sliding of a smooth steel ball probe against human forearm skin (M. Kwiatkowska et
al., 2009). In this work FE was used for the simulation of the deformation behaviour of the forearm skin. The numerical
model was used to assess the usefulness of FE to simulate deformation behaviour in-plane and perpendicular to sliding
direction during reciprocating sliding of a ball probe against human forearm skin. Simulations were made for two different
diameters of ball and two loads. During the simulation the position of a reference point was tracked in the horizontal and
vertical direction. The results of the simulations are in rather good agreement with the experimental results published by
Kwiatkowska et al. Differences between the test results and FE modelling results are on an acceptable level. The main
explanation for the differences is the fact that a 2D model has been used and a constant friction coefficient. The mechanical
properties used were taken from literature and modified to suit (S. Diridollou et al., 2001) (M. Kwiatkowska et al., 2009)
(Geerligs, 2009) (F.M. Hendriks, 2005) (F. M. Hendriks, 2003) (Bensouilah J., 2006) (Hung A., 2009).
During the simulation an average dynamic friction coefficient was used for each probe. In these simulations, the skin is
compressed in front of the probe, forming a “bow-wave” and stretched behind as a consequence of friction and lateral surface
displacement. The same effect is noticed in the experimental study.
A 3D FE model should give better results because it describes better the 3D geometry of the spherical probe. The
experimental part should be improved by Digital Image Correlation (DIC). The DIC can be used to control many reference
points, which is important for validation of the FEM model.
REFERENCES:
Bensouilah J. B. P. Aromatherapy in the treatment and care of common skin conditions [Journal] // Paperback.. - 2006.
Boyer G. [et al.] Dynamic indentation on human skin skin in vivo: ageng effect [Journal] // Skin Research and
Tecchnology. - 2009. - Vol. 15. - pp. 55-67.
C. Pailler-Mattéi H. Zahouani, Analysis of adhesive behaviour of human skin in vivo by an indentation test [Journal] //
Tribology International. - 2006. - pp. 12-21.
6