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FAQ 004257 | How can I deduce the axial stress and hoop stress of a circular container?

Figure 01 - Example Model of Inclined Container

Figure 02 - Unaligned Local Coordinate Systems on Container

Figure 03 - Alignment of Local Coordinate Systems on Container

Figure 04 - Aligned Local Surface Coordinate Systems on Container

Figure 05 - Axial Stresses and Hoop Membrane Stresses on Container

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004257

Process Manufacturing Plants

Mechanical Engineering

Power Plants

Silos and Storage Tanks

How can I deduce the axial stress and hoop stress of a circular container?

Answer

Since there are only the directions x- and y- in the plane for surfaces, it is first necessary to define which should be the hoop stress and which the axial stress. In the following example, sigma_x should be the axial stress and sigma_y the hoop stress.

The example consists of an inclined circular container (Figure 01). After the modeling, the program tries to align the local axis systems on the global axis system (Figure 02). However, the x‑axis should run along the container for all surfaces in this case. This orientation can be achieved as follows.

First, the z‑axis of all surfaces must point inwards or outwards. In the example, the outside direction has been selected. If this is not the case for the surface, you can right-click the surface and use the "Reverse Local Axis System" feature to move the z‑axis to the other surface side. Then, select all surfaces and open the Axes tab in the Edit Surface dialog box. Figure 03 shows the dialog box. In this case, one of the boundary lines oriented axially has been selected. Figure 04 shows the aligned local axis systems now. All x-axes are axial and all y-axes run in the circumferential (hoop) direction.

Figure 05 shows the results of the membrane stresses axial (sigma‑x,m) and along the circumference (sigma‑y,m).