RM Bridge Modeler Help

FE-cross sections and variables

The name FE-cross section is based on the name "cross section of finite elements". All cross sections in RM are plane finite element meshes built of 9-node-Lagrange elements.

Note: A FE-cross section is defined by a reference to its original cross section and a list of current values for the variables. The FE-cross sections are indirectly available by the name of the original cross section at the segment points.

Exporting an cross section to RM Bridge only the first 9 characters will be considered do distinguish the single names. The Cross section names are composed as follows:

[original name]-[part].[variation]   i.e. cross1-01.001

For [original name] only the first 9 characters will be considered. If the name is longer it will be shortened: "crosssection" becomes "crossse!1".

The naming of cross section that are not used in segment points is similar:

[original name]-[part]

At the additional export to an TCL-file the name will be [original name].[variation]

If a cross section is defined by using variables, the FE-cross section can vary at the segment point assigning current values. The current values of variables are calculated from the mathematical expressions.

Note: A later change of a table or formula does not effect an automatic update of FE-cross sections. In that case the values at the segment points have to be updated by the user. This can be done by using the button "Recalc / Eval.Formulas " in the window of the segment point list.

List of current variables

The segment point window shows two lists for the current variables and the corresponding values. One list refers to the cross section "before" of each segment point, the other one refers to the cross section "after".

Modify variable values

The values can be modified by clicking the Modify tool or by clicking the wanted line in the list. Mathematical expressions and the use of formulas and tables defined previously are allowed.

When is a FE-cross section OK?

The FE-cross section is OK and so available for the RM-export, if it consists of at least one defined element and all elements are able to be calculated.

Topological and geometric control

In the Segment-Point-List it is possible to check the FE-cross sections along a segment. If RM Bridge Modeler detects an error, the node or the element will be marked with an "!".

Frequent errors are:

  • A left-hand system of local axes occurs. This may happen by the adaptation of a cross section using tables. The tables or assignments of them have to be checked.
  • A topological error has been found. The element edges of neighbor elements do not fit to each other.
Note: Bad elements will not be transferred to RM.

There are 2 possibilities, to represent a FE-cross section:

  1. Function "Plot - Cross section at segment"

    This function is for plotting all FE-cross sections of a segment and by using the function "Crt" they can be displayed on the screen.

  2. Edit variables at the original cross section

    If the current values are set for the variables at the original cross section, then the cross section is displayed with the dimensions of the FE-cross section.

Note: It is recommended to copy the original cross section to an auxiliary cross section before and to manipulate that auxiliary cross section instead of the original one.
Parent topic: RM Modeler CONNECT Edition
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