Biomedical Engineering Reference
In-Depth Information
Fig. 4.18 Physical buttocks model: a CAD-surface data, b FE-Mesh, c deformed VE-foam
model and d rigid buttock model on VE-foam in section cut view
Fig. 4.19 Comparison of experimental HR-foam material data with simulation output: a zoomed
time range: 0-30 s and b time range: 0-10,000 s
node shell elements, and rigid body characteristics were assigned. All degrees of
freedom except the loading direction were constrained. In addition, point mass was
added to meet the experimental model weight.
Creep testing was performed as described in
Sect. 4.2.1.4
with HR-foam
material and VE-foam material, and buttock vertical displacement was measured
over 3 h. Comparison of experimental displacement-time recording and simula-
tion output are depicted in Fig.
4.19
for HR-foam material and Fig.
4.20
for VE-
foam material.
A Critical Review: The exclusive use of long-term material data in interaction
simulation, without considering time-dependence, underestimates the material
response in most cases. As the Figs.
4.12
and
4.13
show, exclusive use of the long-
term material response is not justified if the material very slowly, over hours or
even days, reaches steady state. Without information on material time-dependence,
