Question

Under plane stress condition in the XYZ Cartesian system, which stress value is correct if a problem is characterized by the stress field σxx=σxx(x,y), σyy=σyy(x,y) and σzz=0?

(a) σxy=0

(b) σyx≠0

(c) σzx≠0

(d) σyz≠0

The question was asked in homework.

Origin of the question is Plane Elasticity in section Plane Elasticity of Finite Element Method

Answer 1

Right choice is (b) σyx≠0

To explain I would say: A state of plane stress in XYZ Cartesian system is defined as one in which the following stress field exists:

σxz=σyz=σzz=0, σxx(x,y), σxy=σxy(x,y) and σyy=σyy(x,y).

Thus, σxx , σxy and σyy are non-zero stresses. Such a problem in three dimensions can be dealt with as a two-dimensional (plane) problem.