Biomedical Engineering Reference
In-Depth Information
Fig. 7.63 3D-seat surface in different perspectives (left and center) as well as with a male Boss-
Model (right)
Fig. 7.64 Profiles of the different seat cushions due to extrusion of a the optimized transversal
contour along the optimized sagittal contour (transopt) and b the optimized sagittal contour along
the optimized transversal contour (sagopt)
The following simulations of body-seat cushion interaction are thus based on
the transopt model (Fig.
7.65
).
As a result of the mechanical interaction between the male Boss-Model and
both car seat cushions, the basic design and the optimized transopt variation, four
distinct regions e-merged where peak stress occurred. Three of these regions were
further differentiated into 12 anatomical positions with different peak stress values.
With the exception of maximum compressive stress S
11
and tensile stress S
t
22
;
as
well as the shear stresses S
13
max
and S
23
max
;
the peak values of all other stress
components occurred at distinctly different locations prior to and after topology
optimization (cf. Fig.
7.66
b and Table
7.12
)(Note: In the following, positive and
negative shear stress are labeled with ''max'' a n d '' min'', respectively).
In Table
7.13
, peak stress S
ij
(i, j = 1, 2, 3) resulting from mechanical inter-
action with the (non-optimized) basic cushion design and the optimized transopt
variation are compared. The optimized transopt variation led to a distinct tissue
stress reduction of nearly one order of magnitude!
Figure
7.67
shows the vertical direct stress S
22
distribution at skin level, at the
fat-muscle interface and at the bone surface of the male Boss-Model, as a result of
interaction with the non-optimized and the optimized transopt cushion variation.
A distinct reduction of tissue stress was observed at the skin level and at the fat-
muscle interface. At the bone level stress was mainly reduced at the ischial
tuberosity and remained nearly unchanged at other bone surface locations (cf. also
