Biomedical Engineering Reference
In-Depth Information
Fig. 4.6 Elastomeric foam characterization: a plate compression test, b hemispherical compres-
sion test with a rigid punch, c quad lap shearing with symmetric fixtures and d buckling phenomena
particular
deformation
modes
under
quasi-static
loading.
The
employed
test
scenarios are shown below in Fig.
4.6
.
Specimen: Prismatic samples were randomly extracted from a block of open-
cell polymeric soft foam material (cf. Fig.
4.7
a) and subjected to plate compres-
sion tests under different climatic conditions to mechanically characterize mattress
and seat foam materials. The obtained force-displacement data of the different
foam samples were nearly identical, which suggested isotropic and homogenous
material behaviour (cf. Fig.
4.7
b). The samples, however, did show a strong
non-linear dependency to temperature and humidity (cf. Fig.
4.7
c). Hence, all tests
were conducted under defined conditions (20C and 50% humidity) in a climate
chamber to ensure reproducibility, (Schrodt 2006); (Schrodt et al. 2005).
For the indentation processes (1) and (2) foam specimens with the dimensions
H 9 W 9 D = 200 9 200 9 50 mm were used, differing from samples used in
