#### Further Information

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• ### Is it possible to give a Solid an orthotropic direction?

A solid can be assigned with stiffness in all three directions (x, y, z). The material model for this is named Orthtropic Elastic 3D or Orthotropic Plastic 3D (picture 1).

The stiffness can be defined for E-Modulus and Shear Modulus of the Solid. The direction is ordered according the orientation of the Solid (picture 2).
• ### Does the calculation in RF-SOILIN work with solids as well?

Yes, the calculation also works with volume cores. Important for the calculation is only that the solid must be embedded with one surface side (base plate). This means that a storage of the volume body is only possible with linear bearings for the calculation by means of RF-SOILIN.
• ### I import an IFC file from another CAD program in RSTAB or RFEM by using the CAD / BIM option. During the conversion, I receive error messages. Likewise, the members will not be converted correctly.

CAD programs that are not primarily structural analysis usually model structural elements as solids. A simple rectangular column would consist of 12 lines and 6 surfaces, for example (see Figure).

The solids can also be defined in different ways. Either over the boundary surfaces (BREP) or as a "drawn solid", so to speak (Swept Solid). The difficulty now is to generate a 1D element from this 3D element. This is usually only possible if the solids were created as Swept Solid. The "Face" surface defines the cross-section. We can determine the correct member position by means of the direction and length of the extrusion.

However, in your case, it is a BREP. For the moment, we can not guarantee the correct conversion for this type. This also applies to the warning that should appear during the import.

• ### How can I create the line where two arbitrarily shaped surfaces intersect in space?

The line can be created by means of the intersection. With the shortcut menu, you can retroactively convert the line created by the intersection into a classical line by using the "Convert to line" function.
• ### In my model, I get the error message 414 for a contact solid. It is not possible to perform a calculation.

FAQ 002544 EN Modeling | Structure RFEM

The message says that the lines of the contact surfaces are not parallel. Therefore, it is recommended to check the nodes of the contact surfaces again and to check whether the lines are really exactly parallel to each other.

• ### How can I quickly create a contact solid between two contact surfaces in RFEM?

FAQ 002443 EN Modeling | Structure RFEM

The quickest way to create a contact solid between two planar surfaces is to use the function "Create Solid by Contact." Select both contact surfaces and select the corresponding function in the shortcut menu (see Figure 01).

The program automatically creates a contact solid including all boundary surfaces and openings in the solid. All you have to do is define the contact properties in the settings for the contact solid (see Figure 02).

• ### Can solids be modeled and statically calculated in RFEM?

FAQ 002423 EN Modeling | Structure RFEM

Naturally, volume elements can also be generated with RFEM. These are above all always useful if it is z. B. is particularly shaped machine components or particularly thick components. Even if an image as a surface element is no longer possible, the image by means of volume elements often offers. As a result of the calculation of solids, we obtain deformations, stresses and distortions.

Other areas of application of volume elements include contact problems. Thus, for example, with a contact volume, the contact conditions of complex connections with the contact properties "failure in pressure" or "failure in tension" for the contact perpendicular to the contact surfaces can be taken into account. Parallel to the surfaces are the properties "Failure if contact with surfaces does not work", "Full power transmission", "Rigid friction", "Rigid friction with limitation", "Elastic friction", Elastic friction with limitation "and" Behavior of the elastic volume "to choose from.

Contact properties between two contact surfaces can also be realized via area approvals (see following general descriptions):

There is already an interesting video from Dlubal Info Day from 14. December 2016 with the topic "Dlubal-Infotag online 2016 - Part 4: Modeling and calculation of volume elements in RFEM "on our homepage :):

• ### How can I create a section through a solid in order to evaluate the results anywhere?

FAQ 002331 EN Modeling | Structure RFEM

• ### I placed two solids on top of each other. There are nodes/lines/surfaces which are used by both solids. Is there a possibility to generate a failure?

FAQ 002280 EN Modeling | Structure

If the contact between two overlaying plates or solids is simulated, you have to model a contact solid between the two plates / solids usually with a thickness from central axis to central axis of both contact surfaces. The material of the contact solid should be the same as for the surfaces in order to be connected. If the surfaces have different materials, we recommend using the material with inferior properties for the contact solid. The following blog entries from our website provide some information about contact solids: Blog entries contact solid. You can also have a look at the following demo video where we show modeling a contact solid: Demo video contact solid

• ### Is it possible to assign a nonlinear material to a contact solid? Which material is most suitable?

FAQ 002272 EN Modeling | Structure RFEM

Nonlinear materials are not allowed for contact solids. It is not possible to make a general statement regarding which material should be used. A contact solid can represent a rubber body or a steel plate. We recommend to select an isotropic material here which corresponds or is similar to the real material in its properties.