Mechanical Interactions - Preventive Biomechanics - page 271

Fig. 6.27 Tissue direct logarithmic strain LE 33 at skin level, fat-muscle interface and bone
surface as a function of time adjacent to the ischial tuberosity using E-BSS 1 and E-BSS 2 body
supports

Fig. 6.28 Tissue logarithmic
direct strain LE 33 at skin level
and bone surface as a
function of time adjacent to
the sacrum using E-BSS 1
and E-BSS 2 body supports

• Skin level tissue direct stress S 33 at the ischial tuberosity using the E-BSS 1
system does not decrease until after approx. 15 min, and a nearly constant level
is reached after 2 h.
• At the sacrum using the E-BSS 1 system, constant tissue direct stress S 33 is
reached after approx. 15 min, whereas at the ischial tuberosity stress declination
is still in progress.
• At the ischial tuberosity, bone level logarithmic direct strain increases steadily
over the considered time span.
• At the ischial tuberosity, the highest shear strain S 23 occurs at skin level.
• At the ischial tuberosity, shear strain is increased distinctively with the E-BSS 1
system (may be associated with the effect of increased buttock tissue

displacement when seated, as discussed in Sect. 7.2 ) .
• At the skin level of the sacrum, with E-BSS 2 system, shear strain strictly
decreases over the considered time span.
• At the ischial tuberosity, taking absolute direct and shear strain values into
account, at the skin/fat level, higher strain can be detected compared to the
muscle

tissue at the bone surface. An objective conclusion about spatial