Analysing 2 Material Cylinder w/ Internal Pressure 100 Units

[Shawndude]

I am trying to analyse a two material cylinder glued together .The cylinder is subjected to internal pressure of 100 units. The problem i am facing is that the radial stress at the inner radius (where the internal pressure is applied) is not equal to the internal pressure.I.E. if the internal pressure is 100 units ,the radial stress at the inner radius is 98.23. It generally deviates by 2 to 3 percent.I am attaching a contour plot of the radial stress.
I have used the following properties;
young's modulus E1=1e5...E2=2e5
Poisson's ratio is 0.3 for both materials
Mesh properties: smart size no:1(fine)
free mesh
plane 182 has been used. It is a cylinder with zero height hence area has been defined.Only quarter cylinder is analysed and symmetric boundary condition has been implemented.
To find radial stress, rsys,1 command has been used

 

[Mech_Engineer]

Have you run a mesh convergence study, where you increase the mesh density and see if the results change?

 

[Shawndude]

Have you run a mesh convergence study, where you increase the mesh density and see if the results change?

I have and the solution does converge but if the mes h is too dense then it crosses the value and keeps on increasing just like in this case where the pressure applied is 100 but stress is 101

 

[Mech_Engineer]

Are you using elements with midside nodes? It seems that your mesh results show that the difference is due to mesh density/discontinuity.

 

[Shawndude]

Are you using elements with midside nodes? It seems that your mesh results show that the difference is due to mesh density/discontinuity.

I am using mid size nodes.