# RFEM

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# 8.13 Surfaces - Local Deformations

To control the graphical display of local surface deformations, select the Surfaces check box in the Results navigator. Table 4.13 shows the surfaces' local deformations in numerical form.

For 2D structures, RFEM only shows the relevant table columns of deformations.

The table shows the displacements and rotations sorted by surfaces. The results are listed in reference to the grid points of each surface.

Grid Point

The numbers of the grid points are listed by surface. They represent the characteristics of each surface. Number and arrangement of the grid points can be adjusted in the Grid tab of the Edit Surface dialog box.

In this dialog tab, you can define the Grid Type, Grid Parameters, or, if necessary, the Grid Origin and Direction of Grid Axis 1. The default setting is a Cartesian surface grid with uniform Grid distances of 0.5 m for the respective grid points in both directions.

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The grid allows for a results output in equidistant, adjustable result points independent of the FE mesh. For small surfaces, the grid's standard mesh size of 0.5 m may lead to a small number of grid points (or even just one result grid point in the grid origin). Then, count and distances of the grid points should be adjusted to the surface size in order to generate more grid points.

When the surface grid is modified, a new calculation of results is not necessary because the grid values are interpolated from the result values of the FE nodes.

The results output in the table is based on the surface results grid. In the work window, both the values of FE nodes and grid points can be displayed. To set the results display, use the Results navigator.

RFEM numbers the grid points automatically. To display the numbers of grid points in the results graphics, select the Numbering check box in the Results navigator as shown in Figure 8.36.

Grid Point Coordinates

Table columns B to D show the coordinates of grid points in the global coordinate system XYZ. When you click into a table row, the corresponding grid point is indicated by an arrow in the work window.

Displacements / Rotations

The deformations have the following meanings:

 |u| Absolute total displacement (not for result combinations) ux Displacement of surface in direction of local axis x uy Displacement of surface in direction of local axis y uz Displacement of surface in direction of local axis z φx Rotation of surface about local axis x φy Rotation of surface about local axis y φz Rotation of surface about local axis z

To display the local surface axes, use the shortcut menu shown on the left or the Display navigator where you select Model → Surfaces → Surface Axis Systems xyz.

When you analyze curved surfaces, the surface axes refer to the axes of the finite elements (see Figure 8.41).