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 modelling 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 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 are adapted.

Parameter List

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

Image 01 - [Edit Parameters] Button in Table Toolbar

Image 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.

A parameter is of a particular 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 in 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 table column F, you can define a 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

The 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.

Image 03 - [Edit Formula] Button in Table Toolbar

Image 04 - Marked Cell Corners in Table 1.1 Nodes

Image 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.

Image 06 - Cross-Section with Parameters

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

Image 07 - List of Parameters

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

Image 08 - Node Coordinates: Edit Formulas

The formulas used are shown in Figure 09.

Image 09 - Formulas of Node Coordinates

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

Image 10 - Parameter Element Thickness

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

Image 11 - Changing Dimensions Using Parameters

Keywords

Formula Formula Editor Parameter Parameter list

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  • Updated 14 December 2020

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