2 Penetration -

Penetration - HM-3320
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In this tutorial, you will learn how to:
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Run the penetration check
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Review the intersection results
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Fix the intersection results
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Interrogate the penetration results
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Fix the penetration results
Tools
The penetration feature can be accessed in one of the following ways:
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From the Menu Bar, select Mesh, then Check, then Components, then Penetration
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From the Tool page, go to the penetration panel
The penetration panel allows you to check the integrity of your model, visualize problem areas, and fix the problem areas. The three entities that can be checked are elements, components and groups. Typically, the group check would be for checking contact definitions (for example, Abaqus/LS-DYNA).
This panel allows you to check components for element penetration and intersection. More importantly, you can correct your model. Penetration and intersection can be used individually or collectively. Penetration is defined as the overlap of the material thickness of shell elements, while intersection is defined as elements passing completely through one another.
Example of penetration
Example of intersection
Strategy
Use the following guidelines for conducting checks on models:
•Checks can be run on both 2-D and 3-D elements, 2-D elements only, or 3-D elements only.
•The include self interference option includes components that bend and pass through themselves. This occurs rarely and is expensive when running the check. By default, this option is off.
•By default the check is set to all interfaces, meaning both intersection and penetration. The intersections only option and the penetrations only option are available.
•The allowable interference depth option allows certain penetrations and intersections to be ignored if less than the value specified.
•An additional option, uniform thickness, allows you to assign a global thickness to all components.
•An additional option, thickness multiplier, allows you to multiply the existing thicknesses in the model.
When the penetration check is invoked, a new penetration tab is invoked in the browser area.
The results are displayed in a tree format for ease of display and are split into intersections and penetrations with the number of components that are clashing in brackets. In the example above, two components are intersecting and eleven components have material penetration. Expanding each tree will provide more detail as to which components have failed. The columns (ID, Elems, Depth, Comps) provide valuable information on which components' IDs are involved, the number of failed elements, the depth of penetration (not applicable for intersections), and number of components affected in the penetration/intersection. Each of the columns can be sorted by clicking the column header. At the bottom of the tab area there is a message bar which will detail the status of the check, the number of failed elements, and any warnings and errors as the checks are invoked.
You can also click the right mouse button to access all of the options and tools within the penetration and intersection check. The context menu will invoke and will provide the option to fix either penetrations or intersections, depending on whether the penetration parent/child folder or intersection folder has been highlighted.
The options button allows for the configuration of the display, automatic fixing (intersections and penetrations), and depenetration vector and configuration of the tree display.
The fixing of penetrations and intersections falls into two categories: automatic and manual. These capabilities will be discussed in more detail in the tutorial.
Exercise
This exercise uses the model file, penetration_check.hm.
Step 1: Retrieve the model file, penetration_check.hm.
1. From the Menu Bar, select File, then click click Open....
2. Browse to the file, penetration_check.hm and click Open.
3. From the Menu Bar, select Preferences, then click User Profiles….
4. Select LsDyna.
This model is an LS-DYNA model, therefore, it is important to chose the appropriate user profile so that HyperMesh can access the actual thickness values of the shell components.
The thickness values are required for material penetration check.
5. Click OK.
6. Click Shaded Elements and Mesh Lines ().
Step 2: Run the penetration check.
1. Go to the penetration panel.
2. To invoke the penetration check, select all the components by clicking comps.
3. Click comps on the right-hand side of the panel, click all, and click select.
4. Click check.
Once the check has completed, the Penetration tab populates. In this example, there are two intersections and 11 penetrations. Expanding the tree the results will display the following:
The tree is populated by a parent/child or master/slave relationship. As an example looking at the intersections, the top line shows the component, Rocker Fwd Top Panel RH
(parent), and then below is component, Rocker Inner Panel RH (child). It is important to understand that there is always a reciprocal relationship; the second entry is Rocker Inner Panel RH (parent) and then the component, Rocker Fwd Top Panel RH (child). In this case there is a one-to-one relationship. It is especially important to understand this when there is a one-to-many relationship (for example, Rocker Inner Panel RH under
penetrations). Clicking the parent component will always show that component plus all the components below (children). Clicking a child component will show that component with the parent component only.
Step 3: Review the intersection results.
1. In the Penetration tab, click the Intersections heading to view all the intersections.
Based on which mode is chosen, certain components are displayed on the screen.
2. Ensure that Display Components with Failed Elements and Fit View to Failed Elements are selected.
3. Under Intersections , click the component Rocker Inner Panel RH . The screen will automatically fit to the failed intersecting elements.
4. Click Review Failed Elements (
) to review the other visualization modes. The contour
and vector displays are only applicable to intersections . The intersecting elements display
as follows:
Step 4: Fix the intersection results.
HyperMesh includes two methods of fixing penetrations: manual and automatic. To fix intersections manually:
1. Under Intersections, click the component, Rocker Fwd Top Panel RH.
2. Click Manual Fix Tools () to ensure that the intersecting entities can be fixed.
Additional buttons populate for intersection fixing.
3. Ensure Elements from Tree Selection is selected – you will not pick any additional elements.
4. Ensure Move in Normal Direction is selected for the direction of movement.
5. For distance value, enter 2.
6.
Click the left arrow button twice and notice the selected elements moving in the chosen direction.
After the elements have been moved by a value of 4, they no longer intersect.
7. Click Recheck () and notice there are no intersections. Only 11 penetrations remain. Important
A dialog box displays that states: "Current results will be lost by rechecking the model. Would you like to continue?" Click Yes. The penetration tab needs to be refreshed.
Alternatively, you can use the automatic fixing tools:
1. Load the file, penetration_check.hm, again.
2. Go to the penetration panel.
3. To invoke the penetration check, select all the components by clicking comps.
4. Click comps on the right-hand side of the panel, click all, and click select.
5. Run the check on all components
6. Highlight the Intersections directory in the Penetration browser.
Notice that there are currently two intersections.
7. Right-click to invoke the context-sensitive menu. Choose Automatic Recursive Intersection Fix – the wrenches will turn green indicating that the fix was successful. The Automatic Recursive Intersection Fix will run through all passes automatically, the Automatic Intersection Fix will run through one pass at a time (most fixes will require multiple passes).
8. Run the Recheck— the intersections have been fixed.
Step 5: Interrogate the penetration results.
1. Expand the penetration tree.
2. Click component, C-Pillar Bot Inner Panel RH.
The penetration results will look as follows:
3. Click the visualization options,
, to view the different types of results
display for the penetration. Remember that the columns can be sorted. For example, if you were only interested in the worst offending penetrations then sorting by the depth column will reorganize the tree structure (while still retaining the parent/child relationship).
In this particular example, for component C-Pillar Bot Inner Panel RH , there are 18
elements that have failed (parent and child), the maximum penetration depth is 0.159, and there is only one component penetrating.
Step 6: Fix the penetration results.
Within the checking tool there is an automatic penetration fix that will remove the penetrations within the model. This works by physically moving the failed nodes to new locations to remove the material penetration. There are two options: automatic penetration fix and automatic recursive penetration fix . Both will do the same thing, but the automatic option often requires you to use it several times successively to eliminate all penetrations, while the automatic recursive completes the fix in one click. However, the iterative option will take longer to complete, because it is essentially automatically repeating the automatic fix until it reaches a point at which no further improvements can be made. You also have the option to either fix individual penetrations by clicking on a single parent branch of the tree, or fix all penetrations at once by clicking and highlighting the complete Penetrations tree.
In some circumstances, there may be the need to lock or freeze a component that cannot be adjusted or moved by the fixing tool. This can be achieved by right-clicking and selecting Lock Component . Once a component is locked, a symbol will appear by the folder indicating that the component is locked.
In the previous example, component C-Pillar Bot Inner Panel RH was locked, notice how the lock symbol appears multiple times to correspond with the multiple references to the same component. To unlock, right-click again and select Unlock Component . For the purpose of this tutorial you will not be using the lock functionality.
To fix the penetrations in the model we will use the Iterative Fix :
1. Click Penetrations at the top of the tree. See the following image.
2. Right-click to bring up the menu and then click Automatic Recursive Penetration Fix.
Important:
A dialog box states, "Model changes to specific tree items are not possible once
process is initiated. The Penetration tab will appear and disappear repeatedly during the process. Would you like to continue?" Click Yes.
After the process has finished, note that the majority of the penetrations have been fixed.
Three penetrations remain which require manual editing to fix.
Go to HyperMesh Tutorials。