Hi, I was simulating the deflection of a diaphragm with uniform pressure acting on it.
Fig 1
I am doing an axisymmetric 2D simulation. We expect the solution to converge as given below with increase in mesh elements.
Fig 2
While meshing, when I increase elements in the radial direction, keeping only one mesh element in the thickness direction as below, with an increase in the element size, I am getting an increase in deflection, which matches the classical curve shown in Fig. 2.
Fig 3
But the moment I mesh in the thickness direction as Fig 4, the trend changes and deflection decreases as shown in Fig 5.
When the number of mesh elements increases, we assume less stiffness and more deflection.
But why is deflection not increasing, as shown in Fig 5, when we start to refine mesh in the thickness direction?
----Added on 09th July-----------
This is the element I used for meshing. "CAX4R: A 4-node bilinear axisymmetric quadrilateral, reduced integration, hourglass control."
These are the values I am getting for deflection at the center with element size.
Until 30 element size, in the thickness direction, there is only one element. Then, with mesh refinement, deflection increases as per Fig 2. The deflection came down once I started to mesh with more elements in the thickness direction.
The good thing is theoretical deflection comes around 4.47 E-9, which is the one I am getting towards the end of my simulation. However, I wanted to know the reason why adding elements in the thickness direction caused less deflection. Is there any mistake I am making? Are there any better elements or integration methods (in Fig 6) I have to choose for this type of problem?
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Thank you,
