Biomedical Engineering Reference
In-Depth Information
Fig. 7.15 a Tissue normal
stress S
33
along node path 2
(see Fig.
7.6
) for all
percentile models at 60 mm
mattress height (red lines)
and 100 mm (black lines),
b comparison of interaction
of system LS2 and BoMo 4
(95th percentile, 41-61 years,
102.5 kg) at a mattress
thickness of 60 mm (top) and
100 mm (bottom)
7.1.4.2 Optimization of the Mattress Height
The interaction simulations comprising the percentile body models presented in
Table
7.6
and the bedding system LS2 showed that an initially assumed mattress
height of 60 mm is not sufficient when considering a larger body mass. The 95th
percentile model (41-60 years, 102.5 kg) for example, caused high foam material
deformation and critical buttock (internal) tissue stress, cf. Fig.
7.15
b.
Increasing the foam mattress height to 100 mm led to a significant decrease in
tissue stress S
33
together with a load relief of the mattress foam, cf. Fig.
7.15
b
(bottom). In Fig.
7.15
a, the normal stress along path 2 (see Fig.
7.6
) of all per-
centile models listed in Table
7.6
were compared for mattress heights of 60 and
100 mm (mass of arms included). Results show significant lower tissue stress at
100 mm mattress height. Including the arm mass resulted in increased membrane
pressure which required a change of initial membrane inside pressure from 2.8 to
3.5 mbar for system LS2.
7.1.5 Optimized Bedding System: Human Models
in Lateral Posture
In the following, the system LS2 which has been optimized based on the human
body models BoMo2 and BoMo4 in recumbent posture (lying on back), is verified
for body loading in the lateral posture (lying on side). In this context, the generation
