Running and analyzing a Nastran Analysis - Demo

00:09

So for this exercise, we're working with this cable sheave part file once again.

00:14

You will notice that it has already been set up from the previous exercises.

00:18

So the boundary conditions, so your Loads and your Constraints,

00:22

as well as the Solid Element Idealization with a material and then a mesh has already been defined.

00:29

So at this stage, this analysis is ready to run.

00:33

So I will select "Run" from the "Solve" panel on the ribbon.

00:37

This will kick off the Inventor Nastran Solver.

00:41

When it's finished, you should get a window that comes up and says Nastran Solution Complete.

00:46

If you are missing a Constraint or a Load or there's some type of instability in the model,

00:52

you may get a Nastran Solution Failed window.

00:55

In this case, we know that this is set up properly.

00:58

So we'll select "Ok" to view the results.

01:01

So the first result that's going to show up is your Stress.

01:04

This is going to be your SOLID VON MISES STRESS by default.

01:08

You will notice, it shows you the legend on the left hand side here.

01:13

And if you'd like to change the type of result being shown, you can simply use these drop down menus right here.

01:18

You have your type, your subtype and then the units.

01:22

So if I change the type to Displacement, it'll show my total displacement in inches.

01:29

And then from here, I can also add in things like animation.

01:33

So at the top where you see the Results panel, there's an option to Animate. If I select "Animate",

01:40

it's going to take this Displacement result along with the deformed model, and it will animate the result in 3D.

01:48

So it shows the load being applied with an exaggerated deformation to show the path that that load would take,

01:54

and the resulting displacement.

01:57

When you're done with animating, you can click "Animate" again to turn it off.

02:02

So now I'm going to take a look at another way that you can visualize your results.

02:06

We've already seen Stress and Displacement plotted as three dimensional contours on our CAD model.

02:13

The other way you can pull results is using the XY Plot function.

02:17

This is going to give you the actual exact values versus their position and their coordinates.

02:25

So for instance, I can right-click on "XY Plot" at the bottom of my browser and select "New".

02:31

This will open up the XY Plot dialog box.

02:34

This is where I can choose Nodal results or Elemental results to plot.

02:39

My nodal results are going to be things like displacement and reaction force.

02:43

Elemental results would be your normal principle or von mises stresses that would be added to your Y-Axis.

02:50

So if I want to plot, for instance, the displacement of each node along a given area or line,

02:59

instead of choosing individual nodes in their positions, I can check the box for Along Selected Entity.

03:06

And I can actually choose this line right here, this vertical edge of my flange.

03:12

And then I can choose on the right hand side here,

03:16

the type of data I'd like to plot, which is going to be Displacement in this case.

03:20

The resulting plot will show the position of each node relative to the origin or its distance away from the origin.

03:29

And then it's going to plot the displacement of each on the Y-Axis.

03:33

So if I click "Show XY Plot", you'll see the Displacement versus Distance from the origin,

03:39

in inches, you'll see that magnitude increase as we get further away from the origin at the bottom of the part.

03:46

So as we go up this line, as we get closer to that load, and this flange bends more,

03:52

we should see that displacement increase along that edge. And that's exactly what the plot is showing.

03:57

What's great about this plot is if you hover over each individual data point,

04:02

it'll give you the actual true value of the displacement and the position.

04:07

If I'd like to save this for future use, I can click, "Ok".

04:11

I can give this a name. So in this case, we'll call it Displacement.

04:15

And then I can click "Save" at the bottom of my window here and it will save it.

04:19

So I'll click "Close" and you'll see it saved under XY Plot as Displacement.

04:24

This is really helpful because I can go back at any point,

04:27

and double click on that plot and it will open up that plot and I can then pull the data again.

04:36

Now, in the next exercise, we will discuss the mesh and making refinements in more detail.

04:41

But it should be noted that if you would like to reduce or change the mesh size in any ways,

04:47

and then rerun the analysis that can be done very quickly.

04:51

If you select "Mesh Settings" from the Mesh panel up top, you'll notice the Element Size here is chosen as 0.787679.

04:59

Your value may be slightly different.

05:01

This value is based off of a percentage of the overall bounding box of the model and it is automatically calculated by the solver.

05:09

If I would like to manually type in a value, I can do so.

05:12

So let's say, I choose roughly half of this. Let's do 0.375 inches.

05:19

And then I select "Generate". This will regenerate the mesh.

05:23

Now the old results at this point are no longer valid because they cannot be mapped to the nodes and elements now displayed.

05:30

So if I select "Ok", and then I click "Run" again, I can regenerate the results for the new mesh.

05:36

Now, there are more nodes and more elements that have been created.

05:40

So this should take slightly longer to solve. But I'll go ahead and select "Run" once again.

05:45

And this is the iterative process that you will typically use when you're performing an FEA,

05:50

in order to determine how sensitive your result is to the mesh size.

05:56

So when the solution is complete, once again, I'll select "Ok" to view the results.

06:01

And I now should see a slightly different result for my Stress. Your Stress will have increased.

06:08

So double check your value for Stress. It should be larger than the prior exercise.

06:13

It may not match mine exactly depending on the version of Inventor Nastran that you're using.

06:19

If you look at Displacement, that value should have also changed, it may have increased, it may have decreased,

06:25

but it should be more accurate.

06:26

Now that we have more elements in the model, capturing that load and capturing the stiffness of the model.