Abstract
We calculated normal stress and shear stress by using finite element method when a whole body of FE human model lies down on the two different compression hardness mattresses. Actually measured pressure values at the sacrum when patients lied down on those mattresses showed good coincidence to the calculated one. From calculation we saw that the standard bed mattress in hospital showed larger normal stress and shear stress than foam type mattress of preventing ulcers. The standard one showed more than 50mmHg pressure inside and outside of body. Especially, a large magnitude of shear stress was calculated around the sacrum.
