Refining meshes

00:03

In this video, you’ll:

00:05

make a global change to the mesh,

00:08

and use the local mesh control tools to refine a mesh around a feature or region of interest.

00:16

In finite element analysis, stress results are highly dependent upon the quality of the mesh.

00:23

A good quality mesh strikes a balance between speed of computing and accuracy of results,

00:29

converges quickly, and provides accurate, error-free results.

00:35

To begin, open the file Refining meshes.f3d in the Simulation workspace.

00:42

After the study has been solved, from the Browser,

00:46

right-click Results and click View Results.

00:50

Notice that the peak stress on this part occurs at the inner radius.

00:57

From the toolbar, select Finish Results.

01:01

Before modifying the mesh, clone the study.

01:05

From the Browser, right-click Study 1, and, from the shortcut menu, select Clone Study.

01:14

The Browser updates with a duplicated Study called “Study 2”.

01:19

Now, in the Browser, under Study 1-Static Stress, toggle ON the visibility for Mesh.

01:27

The canvas updates to display the mesh on the part.

01:31

By default, the mesh is rough.

01:34

This is because rough meshes are easier and faster to calculate.

01:39

However, the trade-off for this speed is often the accuracy of simulation results.

01:46

To increase the accuracy of the results, you must increase the quality of the mesh.

01:53

You can adjust mesh quality both globally and locally.

01:58

To refine the global mesh size, from the Browser, right-click Mesh

02:05

and, from the shortcut menu, select Mesh Settings.

02:10

The Mesh Settings dialog displays.

02:13

From here, under Average Element Size, select Absolute Size.

02:20

In the value input field, you can specify the mesh element size.

02:26

In this instance, the size must be reduced, so enter 4 mm.

02:32

Click OK.

02:34

Now, it is time to regenerate the mesh.

02:37

Again, from the Browser, right-click Mesh, and this time select Generate Mesh.

02:45

A Progress dialog displays.

02:48

After loading, the mesh regenerates to reflect the updated Absolute Size value.

02:54

The mesh size is now smaller and likelier to produce more accurate stress results.

03:02

In addition to adjusting the mesh globally, you can also refine local regions of mesh.

03:08

Pan and rotate the model.

03:11

Again, this is where the highest amount of stress is experienced.

03:16

To locally adjust the mesh for this face, from the Toolbar,

03:22

expand Manage and select Local Mesh Control.

03:27

The Local Mesh Control dialog displays.

03:31

In the canvas, select the face.

03:34

Then, in the dialog, in the Length field, enter a smaller value

03:40

to decrease the length of the mesh in this region.

03:44

In this example, enter 0.75 mm.

03:49

Click OK.

03:51

Again, the mesh must be regenerated.

03:55

From the Browser, right-click Mesh and select Generate Mesh.

04:01

A Progress dialog briefly displays, and the model mesh updates.

04:07

Zoom and pan to review the changes to the local mesh.

04:12

The mesh is much finer on the sweeping face.

04:15

However, the transition between the smaller elements and the larger elements is abrupt.

04:22

This could lead to a poor mesh result.

04:25

To adjust this, from the Browser, right-click Mesh and then select Mesh Settings.

04:33

The Mesh Settings dialog displays once more.

04:37

Expand Advanced Settings.

04:39

From here, you can change the growth rate of these elements

04:44

by adjusting the Max Adjacent Mesh Size Ratio.

04:49

Since the mesh size ratio must be decreased, click and drag the slider to 1.1.

04:58

Under Advanced Settings, you can also change the Element Order.

05:03

Expand the Element Order drop-down.

05:06

You can choose to set the order to Parabolic or Linear.

05:11

For now, leave this set at Parabolic.

05:15

You can also choose to disable Create Curved Mesh Elements.

05:20

Currently, this is set to the most accurate configuration, so click OK.

05:26

Once more, regenerate the mesh.

05:29

Once more, regenerate the mesh.

05:30

In the canvas, the transition from the large mesh elements to the small is now more gradual.

05:39

Save the file.

05:41

As an alternative to manually refining the mesh, Fusion contains tools to automatically refine the mesh.

05:50

To try this method, you will alter the mesh for Study 2.

05:55

From the Browser, select Study 2 to activate it.

05:59

Then, from the Toolbar, expand the Manage drop-down and select Adaptive Mesh Refinement.

06:08

The Adaptive Mesh Refinement dialog displays.

06:11

By default, the Adaptive Mesh Refinement is set to None.

06:17

Under Refinement Control, click and drag the slider to High.

06:22

Click OK.

06:24

Adaptive Mesh Refinement is now enabled, but to engage it, the study must first be solved.

06:32

From the ribbon, click Solve.

06:35

In the Solve dialog, ensure the solver location is set to Locally, and then click Solve.

06:43

The Job Status dialog appears, with a Status bar indicating the progress of the solving job.

06:51

With Adaptive Mesh Refinement enabled, the stress will be calculated,

06:56

and where the stress is high, the mesh will be refined appropriately,

07:01

which will improve the accuracy of the results.

07:05

After the results display, click Finish Results.

07:09

Then, back in the Browser, toggle ON the visibility for Mesh.

07:14

Now you can see that, where the stress was highest, the mesh was automatically refined.

07:22

Save the file.