In addition to our technical support (e.g. via chat), you’ll find resources on our website that may help you with your design using Dlubal Software.
Frequently Asked Questions (FAQ)
Customer Support 24/7
In the default settings of the section results for result combinations, the "Max and Min Values" are displayed. Smoothing is not reasonable in this case.
As soon as you change the result display to "Max Values" or "Min Values," the smooth line is displayed.
AnswerSimilarly to surfaces, there are various smoothing options for displaying the results of support reactions. For a nonlinear support, you should always select the actual distribution to display the results.
It is possible to display or calculate the stresses in RFEM as well as in the add-on module by means of the following smoothing options:
- Constant on Elements
- Continuous Within Surfaces
- Continuous Total
- Continuously by Groups / Continuous by Groups
To compare the results, the same display type and calculation type must be selected in RFEM and RF‑STEEL Surfaces.
In RFEM, it is possible to do this in Project Navigator Display → Results → Surfaces → Distribution of Internal Forces/Stresses (Figure 02). In RF‑STEEL Surfaces, this can be displayed or changed in Details → "Options" tab (Figure 03).
AnswerSmoothing is an interpolation of the existing internal forces. This is explained in the related technical article. The internal forces as such are displayed in the post-processing. The COM interface always shows all internal forces on each FE node. Use the Results example from SDK (FAQ) to check these settings.However, it is possible to distinguish between grid points and FE mesh nodes in the results.
The perimeter of membrane cut-outs is described by boundary lines. These boundary lines can be formed by
Figure 01 - Boundary Lines of Cutting Patterns
- Globally defined boundary lines of the assigned membrane surfaces, or
- subsequently introduced cutting lines for the division of the cuts on the membrane surfaces.
Due to their fixed geometry description (arc, circle, spline, etc.), the global boundary lines are inviolable and are thus also implemented in the determination of the planar sections.
On the other hand, the subsequently applied cutting lines are based on the FE mesh of the surfaces assigned in the cutting line specification and have no influence on the mesh itself.The cutting units encircled with boundary and cutting lines adopt the FE mesh of the assigned surfaces for flattening. Since the cutting lines run through the FE elements themselves, with no regard to the global mesh in the edge area, the edges of the original FE elements cannot be used to describe the cutting pattern limitation. In this case, the affected FE elements in the cutting line area are divided by the cutting lines.
Depending on the orientation of the cutting line, the FE elements are cut in the middle or almost on the edge. Since the FE elements on the edge can cause some problems with the geometry, a certain tolerance limit has been entered for the decision. This limit is used to control the critical aspect ratio between the FE edge length cut off with the cutting line and the original FE edge length. If the ratio is smaller than the given limit value, the section line is warped to the original FE node.Figure 03 - SmoothingThis fact may lead to an "Irritation" of the cutting line if the cutting lines are close to the FE element edges. By reducing the tolerance limit shown, this situation is optimized.
The program does not define any fixed length for the distribution of the boundary line compensation. In fact, the compensation is defined at the boundary line nodes and reacts in connection with the integral flattening depending on the geometry and stiffness.In the calculation, the integral flattening considers all compensation strains on the surface and on the edges with the strains of flattening itself.
The FE analysis determines the results for each FE mesh node. Usually, a continuous distribution of the internal force or deformation is preferable for the graphic. For this purpose, it is necessary to smooth the results, for example via interpolation. However, the question cannot be answered in general as this has to be decided from model to model. Basically, RFEM distinguishes between the following five options:
There is an interesting technical article on this issue.
- Constant on Elements
Constant distribution in the element
- Non Continuous
Interpolation in the element based on the results in special points
- Continuous within Surfaces
Calculation of average at the node within the defined surfaces, followed by the interpolation via the element
- Continuous Total
All results are averaged on the node (independent of the defined surfaces) and then interpolated via the element
- Continuously by groups
It is also possible to smooth results by groups. RFEM provides Generated groups with similar material properties. You can create user-defined groups of surfaces or solids by using the navigator shortcut menu (right-click User Groups).
- Constant on Elements
AnswerThe main reason for this is the FE mesh size as well as the different smoothing of the results. The results should match to each other with an increasingly finer FE mesh. Figure 01 shows a comparison with a relatively rough FE mesh. The support resultant is 16.84 kN. However, the resultant of the surface results is only 14.41 kN. If the FE mesh is refined at this point (see Figure 02), the results are similar to each other. In Figure 03, the FE mesh has been refined further. The results are now exactly equal. The deviation at the beginning can be explained by the singular location and by smoothing of the internal forces.
The load import with the mentioned feature is limited to vertical loads (transfer in 2D structures). If support reactions in other directions are required, they must be transferred manually.
To facilitate the manual import, you can display "Smooth Distribution" for each line instead of the "Actual" support reactions (see the figure). Of course, the finer is the subdivision of the lines, the more exact (more shades) is the result closer to the actual distribution.
Did you find your question?
If not, contact us via our free e-mail, chat, or forum support, or send us your question via the online form.
Wind Simulation & Wind Load Generation
With the stand-alone program RWIND Simulation, wind flows around simple or complex structures can be simulated by means of a digital wind tunnel.
The generated wind loads acting on these objects can be imported to RFEM or RSTAB.
“Thank you for the valuable information.
I would like to pay a compliment to your support team. I am always impressed how quickly and professionally the questions are answered. I have used a lot of software with a support contract in the field of structural analysis, but your support is by far the best. ”