Optimization Potential of the Method - Preventive Biomechanics - page 319

Fig. 7.38 Direct stress S 22 : a section cut view at the ischium, b muscle tissue [as (a) with fat and
foam masked], cushion thickness: 100 mm

Fig. 7.39 Shear stress S 12 : a section cut view at the ischium, b muscle tissue [as (a) with fat and
foam masked], cushion thickness: 100 mm. Note colour scheme set equal contrary to sign
convention

Fig. 7.40 Absolute direct
and shear tissue stress at the
ischium plotted against seat
cushion thickness

thickness increased, the lateral buttock tissue increasingly became involved in the
load-carrying process where direct stress decreased and shear stress increased. The
latter mechanism is due to increased vertical displacement of the buttock tissue in
conjunction

with increasing cushion thickness, consistent with observations