Stress field in cylindrical coordinates

[leumas614]

Can anyone please explain the stress fields in cylindrical coordinates? What is the difference between $$\sigma_{rz}$$ and $$\sigma_{\theta z}$$? What is the difference between stress in the $$r$$ axis and stress in the $$\theta$$ axis? Thanks

 

[Astronuc]

In the polar directions, one deals with radial, r, and azimuthal (hoop), θ, directions/stresses/strains. The hoop direction is normal or perpendicular to the radial direction.

σ_xy, x refers to direction of surface normal on which force acts, and y refers to direction of force component, i.e. σ_xy = stress on x plane acting in y direction.

cf - http://www.efunda.com/formulae/solid_mechanics/mat_mechanics/stress.cfm

When the two subscripts are different, they refer to a shear stress. When the same, they refer to a normal force, which is purely tensile or compressive, but not shear.