ppl in a plane stress problem, it is assumed that perpendicular to the
plane shear stress and normal stress is zero.
but due to the strain in directions parallel to the plane , there must
be a strain in the direction perpendicular to the plane by poisson's
effect, which will cause a normal stress.
so is the assumption made as normal stresses @ surface is zero ( as
surface is free of loads in one direction and hence there is no
deformations possible in the elements on surface) and by omitting the
stress in the interior
Regards
WOT
- posted 14 years ago