Week 5 Sphere pressing on a plate

OBJECTIVE

To carry out a static structural analysis of a sphere pressing on a plate. The deformation is to be captured after the sphere descends up to 4mm into the given plate of material non-linear structural steel.

MODEL IMAGE

PROCEDURE

1. After opening ANSYS Workbench, we are met with the Project Schematic window. Here, we can select the 'System Structural' analysis system on the left. Doing so creates a new project. Here, we can rename the project and also change the material if needed. We will need to right-click 'Geometry' and select 'import'. The file provided for this project should be selected. 

Now, we can add the materials right here and make our job easier for later. To do that, we need to double-click Engineering Data'. This opens up the list of inserted materials. We can pick materials we need from the repository listed here. We need to pick NL Structural Steel, which should be in the General Non-linear Material data source.

After that, we simply need to click the yellow '+' symbol on the material's corresponding 'add' column to add this specific material to the project. Once we are done, we can simply close the tab.

We can then exit out of the engineering data tab and return to the project schematic window, where we can right-click geometry and select 'edit'. This will bring the model up in the Mechanical interface.

2. In the mechanical interface, in the outline, under geometry, we can rename each of the components if needed. The material of the plate should also be assigned.

3. We then need to go to contacts under connections and delete all the available contacts and create a new one. To do so, right-click contacts > insert > Manual Contact Region. The contacts surface would be that of the sphere and the target would be that of the plate. The other settings are assigned as follows:

4. Since this model is one-fourth of the original, we are to introduce a symmetry attribute to complete the model. To do that, we can go to model in the outline and right-click it > Insert > Symmetry. Then we need to right-click symmetry > select 'Symmetry Region'. In this menu, all we are to do are select the surfaces about which symmetry is to be applied, along with the axis that will be the symmetry normal. This process is repeated twice to complete the whole.

5. We can then go for the default mesh. After that, we can take care of the solver settings - which would have a direct solver type and large deflection would be turned on. There shall be 4 steps.

6. Moving on, we can insert the boundary conditions. For that, we go to Static Structural > Analyses Settings. Right-click analysis settings > insert > fixed support. For this fixed support, we shall be picking the bottom face of the plate.

We shall also be inserting a displacement condition using the same process (right-click static structural > insert > displacement). For this, we shall be picking the top surface of the model and the tabular data is to be as shown in the screenshot. The displacement comes back to 0 from a maximum of 4mm to convey the retraction of the sphere (along the Y axis).

7. Now we can generate the outputs. To do this, we can right-click Solution > Insert > Strain > Equivalent (Von-Mises) (for equivalent strain) and right-click Solution > Insert > Stress > Equivalent (Von-Mises) (for stress) and right-click Solution > Insert > Deformation > Directional (Y Axis). For each of these outputs, we can specify the geometry to be analysed. Our primary concern is the effect of the sphere on the plate, so we need to ensure outputs are generated specifically for the plate.

Now, all we need to do is right-click solution again and click 'Evaluate all results'.

Finally, when the analysis is done, we can view the results by simply clicking each of these solution entities we created, in the Outline menu.

OUTPUTS

Stresses - Plate

Maximum & Minimum Stresses

Strains - Whole Model

Strains - Plate

Maximum & Minimum Strains on Plate

Directional Deformation on Plate (Y Direction)

Maximum and Minimum Deformations on the Plate

RESULT

As can be seen from the outputs, there was a maximum deformation of 3.4mm into the plate. NB: The sphere was given a displacement condition of a maximum of 4mm as required, which does not translate into an exact 4mm deformation on the plate due to there being an initial gap between the sphere and the plate.

The plate was deformed permanently. In other words, plastic deformation occurred after the sphere was retracted to its original position.

And hence, a static structural analysis of a plate pressing on a sphere was carried out with the outputs of stresses, strains and deformations on the plate (of material Non-Linear Structural Steel) being generated.