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Frequently Asked Questions (FAQ)
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AnswerWith the FE mesh refinement, it is also possible to create an aligned FE mesh in the program. Thus, the automatic FE mesh generator can be controlled to a certain extent. However, it is not possible to use it for setting of a specified mesh geometry.
The stiffness type "Membrane Without Tension" describes the plate and block stiffness of surfaces.The plate stiffness including the shear stiffness perpendicular to the surface plane is linearly elastic and the plate stiffness in the surface plane is defined nonlinearly elastic with the material model according to "Drucker-Prager" depending on the defined thickness and the assigned material.In order to ensure that the surface behaves "Without Tension" in the pane direction, the nonlinear material model reacts with yielding tensile stress fy,t going to almost zero in tension-loaded elements in combination with a relatively small hardening modulus Ep . For compression forces, however, the elements remain linearly elastic due to a relatively high yielded compressive stress fy,c and react with an unrestricted compression transmission.Since the "Membrane Without Tension" stiffness type fundamentally modifies the wall-related degrees of freedom of surfaces, it is only applied to surfaces of the relevant model types 3D, 2D - XZ (uX/uZ/φY) and 2D - XY (uX/uY/φZ ).To better describe the partial nonlinearity of this surface stiffness type, the release RFEM 5.06.1103 from 4.02.2016 renames the type from "Without Tension" to "Membrane Without Tension".The Knowledge Base article "Modeling Approaches for Shear Bearing Connections by FEM" shows a possible application.
AnswerRFEM includes an interface to programs from Dlubal. Input data of all versions of the previous executors forcan be imported without difficulty. can also open the structural files directly and them with surface or elements. Conversely, you can open RFEM 5 files in RSTAB 8.There is a direct link to the CAD applications ofand (but not for LT versions). With RFEM, you can use the advantages of BIM ( ) to exchange data models for digital planning.
Rotated surfaces are often used in RFEM to easily model and calculate geometrical conditions. However, if you use a large number of rotated surfaces in the model, you may experience performance drop. This is due to the definition of the surfaces, because they have to be generated in the background again and again using the boundary conditions if a change occurs in the structural system.
Therefore, it is recommended to replace the rotated surfaces by the surfaces of the 'Quadrangle' type, which significantly reduce the amount of data. Furthermore, the quadrangle surfaces also allow you to apply loads to parts of the surface only.
AnswerYou can use the surface releases, but you need to separate the overlapping part with an own surface. Overlapping surfaces should be avoided in general and can be checked by the "Model Check" (Tools → Model Check → Overlapping Surfaces). Please watch the video file (see link below) to see the approach. Alternatively you can add a "Contact Solid" between the two surfaces.
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