In this video, learn about the concept of rapidly checking the sense of an FE analysis, and learn to use the appropriate tools in SOLIDWORKS Simulation.
- [Narrator] Stress contour plots are one of the most powerful ways of reviewing component strength. There are lots of options available within SOLIDWORKS post-processing, and we're going to explore some of these. Let's go to the Results icon in the Analysis feature tree. We got Stress1 vonMises. Now we've got various controls available for the contour plot. We're going to use this region as the target in here that we're looking at. So right mouse click on Stress1 vonMises, and select Chart Options.
So, uncheck all the options shown here, Display Options, apart from Show legend. So, min and max annotation I'm switching off, and also the plot details are disappearing. So we just got the legend, which is the legend over here, which is left. This cleans up the contour plot considerably. Now the maximum and minimum stress values are shown grayed out on the controls here. We've got an option to override them. Let's say we only want to show peak stress zones.
Uncheck the Automatically defined minimum value checkbox. And in the value here, I'm going to type 20000. Now we want to change the default color. And let's change that to a gray color. So now we have a clipped contour shown. Let's zoom into that. So now only stress contours above the 20000 band are shown there.
Choose the form tab labeled Settings, go to Boundary Options, we can change the type to Model. Now this can be useful to hide the mesh for a cleaner overview of the stress distribution. We always need to be aware of the underlying mesh, but sometimes it can obscure detail. So this can be a very useful plot to review those local stress concentrations. Let's go to the full view. So go to standard.
Now I can see very clearly the regions of high stress concentration. So let's zoom in on the end there. And we can see where we'd be specifically concerned with stresses over say 20000. Let's go back to Boundary Options. And, at the moment we are on Model. Let's select that to None. Now the hard edge of the model disappears. Again, for aesthetic reasons that can be quite useful. So let's switch Model back on again, and we can see the difference.
That's with Model on. And that's with None. Now we're going to set back to Mesh, so we can always see the mesh distribution underneath, and that's very important to be able to assess the quality of the analysis results. So we're going to stick with that for the rest of the demonstration. Under Fringe Options, at the moment we have Discrete. And that's again what we're going to be using for the majority of the analysis work.
If we change this to Continuous, then you can see we've got a more photorealistic kind of distribution. So again if I zoom in locally, it's a smoother kind of plot in there. Again it looks very photorealistic, but we got to be careful not to get too carried away with this, because it can smooth stresses out in a very non realistic manner. And to be honest, it's really more of a marketing tool. Now both point and line options can be useful.
So let's look at point. Not so useful here, because a very cluttered view. And if we go to Line, then again, in an area of higher stress concentration, it can be quite useful to see a visualization like that. And if I switch the boundary option Model, then we get a very clear view of where the local stress concentrations are.
So we're going to be using a mixture of all these different types of techniques, depending exactly what it is we want to show in the reports. Go back to Discrete. And we switch the mesh on. And that should always be our default kind of position. Now we can control the stress type. At the moment the default selection appears as vonMises. But if we go to Definition. Go to Display. Click on the dropdown, we can see a wide range of different stress types in here.
And again, we're going to choose different stress types depending on what the objective is. You always need to make sure that units are set, corresponding to what we want to look for. If for some reason the client wanted to see stresses in another system, say at Newtons per meter squared, which is a strict SI units, on the fly we could convert that to SI units, which again could be quite useful, if we're doing for example a multinational type of project. At the moment we're going to stick with psi. Now if we go to the Advanced Options, at the moment the radio button is set to Node Values.
Now these are values averaged at the nodes, with contributions coming from all the adjacent elements. It has the effect of smoothing the stress distribution, and the smoothing is somewhat arbitrary. When we are looking for high quality stress results, for example with fatigue analysis, or a brittle material, stress smoothing can be bad news, as it disguises peak stresses. Now in SOLIDWORKS, we can't switch off stress averaging, which is a drawback for serious analysis work.
However, what we can do is to use element values. So let's switch on Element Values. We go to the Chart Options tab, and check Automatically defied minimum value. Check OK. The contour view is now very disrupted. And it's based on the element average stress values. There's no smoothing between them. It can give a clearer picture of how good the stress distribution is in practice. A very ragged plot will show that we actually were doing a lot of stress smoothing in the post processing, and the underlying stresses are quite disruptive.
So we're trying to get smooth bands of stress contours in every sense. Now the peak values, if I move out here, we can just see the peak values shown in here. It's below the value that we had for the nodal values, so we can't use these directly to estimate stresses. However, the pattern does show us how good or bad the overall element stress representation is. If we're trying to achieve a very fine mesh convergence, where we're saying we have sufficient mesh to prove that we've actually reached that target accurate stress value, in the limit, the stress average values, shown here, should be the same as the nodal average stress values.
So if I switch between this plot, and I go to my Advanced Options and change this to Node Values, the peak values shown here, and if i just move that out of the way, we can see it's about 34710 psi. If I now switch to Node Values, and redo the plot, you can see the value jumps up.
So somewhere between 34000 and 37000 would be an accurate smooth stress value, which we'd be seeing in here. Mesh convergent studies are very important. What we're trying to do is convince the reviewer, the checker, that the stresses shown in here are accurate. That requires very fine mesh, very regular mesh. And when we've achieved that optimum number of elements, and shape of element, then we've achieved a good convergence. In other words we've settled down to a stress value which is an accurate value.
So without the ability to switch of mesh averaging, this is really about the best we can do. We're looking for see stress jumps across adjacent elements. So at this point, we can close the database because we don't need to save the model, as we haven't made any changes. So in conclusion, there are many powerful options within the contour controls, and it's really a good idea to plan out in advance a set of contour options. For example, a general view, detail views, and so on. Good use of these controls would really help the stress visualization, and improve the quality of the report that you're going to be sending over to a reviewer or a checker.
- Setting up Simulation properties and defined views
- Preparing the geometry
- Setting up a local coordinate system
- Splitting surfaces
- Defining the constraint and the loads
- Running analysis
- Contour control
- XY plots