Defining Thicknesses

For models analyzed in the Planar reference, each element in the mesh must be assigned a thickness value. By default, a unit thickness is assigned to each Planar element. The thickness for a geometric surface, an element, a group (set) of elements or all elements can be given as a constant, parameter, or formula.

The below animation shows a parametric thickness being assigned to a surface:

Note: if the thickness assignments are piecewise constant, updating the reference from Planar to Extrude will result in the Planar mesh being automatically extruded about the midplane into an equivalent 3D solid mesh, with 1/2 thickness extrusions in the +/- global Z axis.

Constant Thickness

Most frequently you want to assign a constant thickness to all elements. To do so, select Select > All Elements > Selection and enter the value of the constant in the Thickness field. Click on the Accept button and StressCheck will confirm your entry in the record listbox directly under the C/A/O/M combo-boxes. If you wish to assign different thicknesses to different elements, select Select > Any Element and click on the elements to which the thickness is to be assigned. The elements will be highlighted.

Alternatively, make a marquee pick to select the desired group of elements. If you wish to remove one or more elements from the selected group, hold the Ctrl key down while selecting the element to be cancelled. Enter the desired thickness and click on the Accept button.

Parametric Thickness

You can assign thickness using parameters. When you enter the parameter name in the Thickness field, you are indicating that a constant thickness will be assigned to an element or group of elements the value of which is computed from the parametric expression entered in the corresponding input field.

Any expression using already defined parameters and constants can be used. For example, assume that two parameters TH and A have been defined. The parametric thickness can be defined as 2*A+TH which means that the selected element will have a constant thickness equal to the evaluation of the current values of A and TH. If A and TH are modified, the thickness will be automatically updated.

Formula Thickness

Once again, the assignment may be element by element or through a group of elements. Complete the Formula entry form with the name and expression for the thickness to be assigned. In the Thickness input field enter the Formula name and, if the formula is defined in other than the global coordinate system, enter the System name. Click on the Accept button and your entry will be confirmed in the record listbox.

The Object: System is only applicable when Formula is used. It has been added to the list of possible objects to facilitate the search of a system name. With System selected, if you click on a system its name will appear in the Status Line. You can then check that system name from the System field.

Assigning Thickness to Elements

To assign a thickness to an element or group of elements, select the Thickness tab in the Input dialog. You may then specify all elements in the model (All Elements), elements one-by-one or a group of elements (Any Element), one or more surfaces (Any Surface), or a fully enclosed group of surfaces (Mesh Region) for assignment of thickness. Finally, click Accept to add the thickness assignment record.

Selecting Objects for Thickness Assignment

If the assignment is to be based on the selection of objects, then in the Model View simply left-click on the objects to which the property is to be assigned.

• If the assignment is to a group of elements, for example, then left-lick and drag the cursor to enclose the desired group of elements in a marquee selection. The selected elements will be highlighted and ready for assignment. Note: it is important to disable the Wetted Faces toggle if internal elements are to be included in the marquee selection.
• If you wish to add one or more elements to the selected group, hold the Shift key down and left-click on the elements to be added to the group.
• If you wish to remove one or more elements from the selected group, hold the Ctrl key down and left-click on the elements to be removed from the group.
• If you wish to cancel the current selection of objects, simply right-click on the Model View.

Note: assignments may also be made to geometric objects via Mesh Region or Any Surface. Elements associated with these objects will automatically inherit the thickness assignment.

Specifying a Set for Thickness Assignment

Alternatively, if a there is a set definition containing a list of objects for assignment, the name of this set may be specified in the Set: combo-box instead of selecting the objects from the Model View. Simply select the name of the set, and the objects in the set list will automatically be selected in the Model View.

Note: automeshed element sets are automatically generated, and are identified by _AUTO_B_#, where # is the number of the automeshed body.

Adding a New Thickness Record/Assignment

To add a new thickness record if an existing record has already been selected from the record listbox, you first must choose Set: New Set or re-select the action, object, or method. Then, you are able to create the new thickness record as usual.

Replacing/Deleting Thickness Assignment Records

If the user wishes to edit the data in an existing thickness assignment record, or delete an existing thickness assignment record, the user first selects the thickness assignment record from the record listbox directly under the C/A/O/M combo-boxes. Once it is selected, the Status column will read “Selected”, signifying the record can be replaced (updated) or deleted.

Replacing a Thickness Assignment Record

Once a thickness assignment record is selected, the user may update the data in the Define tab, and then click Replace to update the thickness assignment record. After clicking Replace, the Accept button will become active and the Replace and Delete buttons will become inactive.

Deleting a Thickness Assignment Record

Once a thickness assignment record is selected, the user may click Delete to delete the thickness assignment record. After clicking Delete, the Accept button will become active and the Replace and Delete buttons will become inactive.

Removing All Thickness Assignment Records

To remove all thickness assignment records, click the Purge button.

Checking Thickness Assignments

Use Action: Check to check for consistency in the thickness input data for all elements in the mesh. It checks whether all elements have a thickness assignment and whether there are multiple thickness values assigned for the same elements. After clicking the Accept button, a report is displayed in a tab above the Model View. The elements without assignment or with more than one assignment are identified by the element number in the report.

Visualizing Thickness Assignments

The pulldown menu under the Display Thickness button of the Attributes Toolbar can be used for visualizing the thickness in different ways.

• The Display Values option applies to the input data only. It displays the formula/table/parameter name or the value of the constant assigned thickness on each assigned element.
• The Outline option displays an outline of the thickness in the Z-direction.
• By selecting the Grid option, the thickness can be displayed at grid points inside the elements, as well as at the element edges.

To visualize the displayed thickness, select the rotation icon from the Views Toolbar, click on the Model View (any location) and drag the mouse while holding down the right button, until the desired view is obtained. The scale of the displayed thickness can be adjusted with the up and down arrow buttons.

Note: If no thickness is assigned to one or more elements, a default value of unity is assumed if the Display Thickness button is turned on. If a Formula was assigned, and the evaluation of the formula gives zero thickness at any location inside the mesh, a warning message is displayed. After the thickness information is entered in the database, a summary of the thickness assignment record is inserted in the record listbox.