Creating Parametric Cross-Section

Technical Article

The stand-alone program SHAPE-THIN determines characteristic values and stresses of any thin-walled cross-sections. Graphic tools and features allow for modeling complex cross-section shapes. In addition to the graphical input, it is also possible to enter the data in tables. As an alternative, you can import a DXF file and use it as a basis for further modelling. Also, each cross-section can be entered using the cross-section library of Dlubal Software and combined as a part with the user-defined elements.

Frequently, there is the requirement to create s cross-section series, meaning the same cross-sections with different dimensions. Parameters allow you to quickly and easily modify the cross-section dimensions. The parameters can be used in formulas to determine a numeric value. You can edit the formulas using Formula Editor. If a parameter is changed in the parameter list, the results of all formulas using this parameter will be adapted.

Parameter List

The parameters are managed in the parameter list, which can be opened by clicking the [Edit Parameters] button in the toolbar of the input table or in Formula Editor.

Figure 01 - [Edit Parameters] Button in Table Toolbar

Figure 02 - [Edit parameters] Button in Formula Editor

The parameter name (Column A) should not contain any spaces and may only be assigned once. This parameter is used to address the parameter in the formulas.

The parameter is of a certain type (Column B). Distances should only have one parameter of the length type, for example. Depending on the type, the corresponding particular unit (Column D) can be selected.

You can enter the parameter value directly into Column C or define it using a formula in Column E. In addition to the general mathematical operations, the verification is possible using the If and Max/Min functions. The $\$$ reference can refer to a specific table. For example, $\$$1.1(A1) uses the value of the cell A1 of Table 1.1. In Column F, you can set the range of values to control the values of Column C.

In addition to entering the parameters in the 'Edit parameters' dialog box, it is also possible to import them using an Excel file.

Formula Editor

Formula Editor manages the equations of the parameterized input. You can open it by clicking the button in the table toolbar, the yellow or red corner in the table cell, or the function buttons next to the text box in the dialog boxes.

Figure 03 - [Edit Formula] Button in Table Toolbar

Figure 04 - Marked Cell Corners in Table 1.1 Nodes

Figure 05 - Function Buttons in Shortcut Menu in 'Edit Node' Dialog Box

The formula can be entered in the 'Formula' text box. It can include constant numerical values, parameters, or functions. The content of the other cells can be used in formulas via references. A reference starts with an exclamation mark and the reference cell is placed in brackets. For example, !(D2) is the value of the cell D2).

Example

The cross-section shown in Figure 06 is to be entered parametrically in SHAPE-THIN 8.

Figure 06 - Cross-Section with Parameters

For this, the parameters shown in Figure 07 are defined.

Figure 07 - List of Parameters

Then, node coordinates can be defined using formulas (see Figure 08).

Figure 08 - Node Coordinates: Edit Formula

The formulas used are shown in Figure 09.

Figure 09 - Formulas of Node Coordinates

In the next step, the element thickness is assigned using the corresponding parameter (Figure 10).

Figure 10 - Parameter Element Thickness

By changing the parameters, the dimensions of the cross-section can now be easily adjusted (Figure 11).

Figure 11 - Changing Dimensions Using Parameters

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Cross-Sections Thin-Walled
SHAPE-THIN 8.xx

Cross-Section Properties Software

Section properties, stress analysis, and plastic design of open and closed thin-walled cross-sections