Creating Parametric Cross-Section

Technical Article

10/26/2017

001489

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.

It is often necessary to display profile rows, that is, the same profiles with different dimensions. Parameters allow you to change the cross-section dimensions quickly and easily. The parameters can be used in formulas to determine a numerical 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, which can be opened by clicking the [Edit Parameters] button in the toolbar of the input table or in Formula Editor.

The name of a parameter (column A) must not contain any spaces and may only be assigned once. The name is used to refer to the parameter in the formulas.

A parameter is of a particular type (column B). For example, Distance should only be assigned one parameter of the Length type. 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. With the \$ \ $$reference, you can refer to a specific table. For example,  \$$ 1.1 (A1) uses the value of cell A1 in 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 via 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.

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 is introduced by an exclamation point; the reference cell is set in brackets. For example,! (D2) uses the value of cell D2).

Example

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

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

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

The formulas used are shown in Figure 09.

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

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