Biomedical Engineering Reference
In-Depth Information
Fig. 6.13 Qualitative agreement of anatomical regions 1 and 2 of increased tissue (direct
vertical) stress from simulation (a) and diagnostic findings of a grade-IV pressure sore (b).
Regions of increased compressive stress are depicted in red. Image (b) is adopted from
a = 1, where V is the left stretch tensor defined in
Sects. 3.2.3.5
and
3.2.3.6
,
respectively.
Generally, in body-support interaction analysis on the supine body, anatomical
regions of increased tissue stress and strain can be identified. They correlate to
diagnostic findings of pressure sores in the gluteal region, cf. positions 1 and 2 in
Fig.
6.13
.
Static and transient static analysis were conducted to quantify tissue stress and
strain at the indicated body sites, i.e. the sacrum (median sacral crest and spinous
tubercles) and the ischial tuberosities, cf. Figs.
6.13
and
6.12
, respectively.
Viscoelastic effects of tissue and foam materials were accounted for and material
5.9
. For the static analysis, the corresponding long-term parameters were used.
Tissue direct (vertical) stress S
33
, logarithmic direct strain LE
33
and logarithmic
shear strain LE
23
(see Fig.
6.14
for axis directions) were evaluated at element
integration points at the skin level, the fat-muscle interface and at the pelvic bone
structure.
6.2.5.1 Elastic Body-Support-Systems (E-BSS)
In the following, the interaction behaviour of the contact partners, technical sup-
port device (TSD) and B
OSS
-Model, was analyzed solely based on their elastic
material properties using the materials parameters based on the identification
