Learning Forum

[las1234]

[peteroznewman]

Shell elements have an assigned thickness and are meshed on a zero thickness surface. The surface has a normal vector. The side of the surface where the normal vector is pointing away from the surface is called TOP, the side of the surface where the normal vector is pointing into the surface is called BOTTOM.
Normal stress in the plane of the shell element that is experiencing bending will have tensile (positive) stress on the top and compressive (negative) stress on the bottom (or vice versa if the bending is reversed).
Position is the station through the thickness for the stress data being plotted. If you have Show Thick Beams and Shells turned off, you only see the zero thickness representation of the shell element. If you have Position set to Top/Bottom for Position, as you rotate the view to look at both sides of the surface, you will see the top stress on the TOP side of of the element and you will see the bottom stress on the BOTTOM side of the element. If you have the Position set to TOP, you will see the top stress on the element no matter which side of the element you are looking at, same goes for BOTTOM. Obviously, the default of Top/Bottom is the best.
If you have Show Thick Beams and Shells turned on, you can even see the stress changing through the thickness when you look at the side of the element.

[las1234]

Thank you for your Time .
i have a geometrie with Shell181 . it's Torus with 0,2 mm Thickness .
what i understand if i want to plot the Bending Stress i should use Position Top ?
and about the shear Stress how can i have it ?
thanks

[peteroznewman]

Here is a mesh of Shell181 elements.

Insert an Element Triad to see the local element coordinate system.
Insert a Bending Stress plot. You don't have a Top/Bottom choice on this plot, you can choose to plot in the element 11 direction = local X axis or the element 22 direction = local Y axis.
Insert a Membrane Stress plot.

[las1234]

Hi Thank you again .
i receive this message when i make the Bending stress " a result bending stress longitudinal is not contained in the result file ansys " and membran too .