# Finite Element Analysis of an ASTM A36 Plate

Member

Dear ANSYS,

I am analyzing a 6mm thickness 1894mm diameter spade for fitness for blind-off service. The material of the spade is ASTM A36 and the load is air pressure @ 1.37bara. The inside diameter of the enclosing circular duct is 1830mm, while the faces "D" of the spade below will be fastened in the flanges of the duct. I created a 30degrees model of the spade and applied displacement (Symmetry) boundary conditions to the cut faces and fixed support to the fastening faces, as shown.

Figure 1: Boundary conditions

Figure 2: Equivalent Stress

I have applied my pressure load on the free face of the plate as well as the fastened face, please is this set up correct?

The maximum stress is concentrated at a point of one of the cut faces (as shown on above figure 2) and was the case through the mesh refinement. Please what could I be doing wrong as I expect that the stress concentration will be uniform across a radius close to the constrained face and not localized at a point?

I need help from anyone who can be of help.

Many thanks for your anticipated support.

Ayodele1.

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• Member

You created basically the same post here: https://forum.ansys.com/discussion/20636/fea-of-spade-installed-on-an-air-line

It's best to use a single discussion to ask questions about one problem.

I agree with what @apwang wrote in that other discussion, you should model this with shell elements on midsurface geometry. Make sure you use Symmetry correctly.

• Member

Thank you Peteroznewman;

I do not quite understand the advise to model with shell elements on the midsurface?

Above is the hexahedral mesh I have at the moment, the skewness is less than 0.5 around the outer parts of the plate but higher at the transition areas i.e. around the center of the plate.

I look forward to your clarification on using shell elements on the midsurface.

Ayodele1

• Member
edited October 1

Open the Geometry in SpaceClaim. Click on the Prepare tab, click on the Midsurface Tool, click twice on your solid body. SpaceClaim will create a surface at the center of the solid body, and set the solid body to Suppress for Physics. When you refresh the Project, the surface body will be sent over with the thickness assigned. When you mesh that, it will be meshed with shell elements.

Apply your loads and symmetry regions to the face and the edges of this surface.

• Member

Thanks a ton!

• Member

Dear ANSYS,

I need clarification as to what pressure I should apply as part of my boundary condition.

This is a pipe (internal) flow and the plate to be installed "normal" to the air flow, should I be using gauge pressure or absolute pressure?

Thanks in anticipation.