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
AnswerBasically, the surfaces of the model have the FE size that was preset in the general FE mesh settings.You can add "FE Mesh Refinements" locally to a surface model.This has the effect that the general finite size can be retained in the FE mesh settings, but the mesh is locally refined so that more accurate results can be expected from the calculation.In this case, the FE mesh refinement can be performed on nodes, lines, and surfaces. The setting can be found in the "Edit" dialog boxes of the node, line, or surface.By using the local FE mesh refinement, it is possible to keep or even increase the general FE mesh size. Thus, it is possible to keep the total number of elements in the model relatively low.
Friction represents a nonlinearity and can therefore only be modified via the interface to the member end release hinge.
For this purpose, the member end release must be created first, if not already available. Then, the IMemberHinge interface is brought to the member end release and then to the nonlinearity (here IFriction ). Then , you can use the methods GetData and SetData to modify the data (here Friction ):Sub SetMemberHingeFriction ()Dim model As RFEM5.modelSet model = GetObject (, "RFEM5.Model")model.GetApplication.LockLicenseOn Error GoTo eDim data As IModelDataSet data = model.GetModelDataDim hinge (0 To 0) As RFEM5.MemberHingehinge (0) .No = 1hinge (0) .RotationalConstantX = 1hinge (0) .RotationalConstantY = 2hinge (0) .RotationalConstantZ = 3hinge (0) .TranslationalConstantX = 4hinge (0) .TranslationalConstantY = 5hinge (0) .TranslationalConstantZ = 6hinge (0) .Comment = "Member Hinge 1"hinge (0) .TranslationalNonlinearityX = FrictionATypedata.PrepareModificationdata.SetMemberHinges hingdata.FinishModification'get interface for member'Dim imemhing As IMemberHingeSet imemhing = data.GetMemberHinge (1, AtNo)'get interface for nonlinearity'Dim iFric As IFrictionSet iFric = imemhing.GetNonlinearity (AlongAxisX)'get friction data'Dim fric As Frictionfric = iFric.GetDatafric.Coefficient1 = 0.3'set friction datadata.PrepareModificationiFric.SetData fricdata.FinishModificatione: If Err.Number <> 0 Then MsgBox Err.Description,, Err.SourceSet data = Nothingmodel.GetApplication.UnlockLicenseSet model = NothingEnd Sub
For Coefficient Vy + Vz, Coeffcient2 is used to set the second coefficient. The translational spring in the Friction dialog box is controlled by the translational spring of the Member-End Hinge. In the concrete case, this is TranslationalConstantX for the x-direction (see Figure 01).
The definition of slippage is recommended here. To do this, you have to set the partial effect in the & quot; Non-linearity & quot; edit dialog box of the dialog box & quot; Edit Nodal Support & quot ;. In the "Nonlinearity - Partial Effect" dialog box, you can now define a Slippage in the corresponding zone. The adjoining diagram is used for the check, see Figure 1.
The difference between both material models is as follows:
In the Isotropic Nonlinear Elastic 1D material model , no plastic deformations are considered. This means that the material returns to its initial state when the load is released.
For the material model isotropic plastic 1D, the plastic deformation is considered.
For both material models, the nonlinear properties are defined in an additional dialog box. When entering data by means of a diagram, it is possible to define a distribution after the last step in both models.
For the material model Isotropic Nonlinear Elastic 1D, it is possible to enter the stress-strain diagram (different for the positive and negative zone) in an anti-metrical way, whereas for the isotropically plastic model 1D, only symmetric input is possible.
AnswerWith the option "Divide the members by the nodes on the members", a member is internally divided at the member locations where nodes are located.
The structure shown in Figure 1 includes two members, member S1 from node 1 to node 2 and member S2 from node 3 to node 4.
If the option "Divide the members by the nodes lying on the members" is activated, member S1 is internally divided at node 4. Thus, the member S1 is connected to the member S2, which you can also see in the deformation (Figure 2).
If the option "Divide the members by the nodes lying on the members" is deactivated, member S1 is not divided at node 4. Thus, member S1 is not connected to member S2. Figure 3 shows the deformation in this case.The structure shown in Figure 4 includes the member S1 from node 1 to node 2. On the member, there is node 3, to which a nodal load P Z = 50 kN is applied. The nodal load only loads member S1 if the option "Divide Members via Nodes on Members" is selected (Figure 5). If this option is deactivated, member S1 is not loaded by this nodal load (Figure 6).
AnswerTrapezoidal sheeting is already available in the cross-section library of RFEM. These cross-sections are primarily used for stabilization measures in the RF- / STEEL EC3 add-on module and as a template for modeling surfaces. A design as a member is thus not possible.The easiest way is to first model the trapezoidal sheeting as a member. Subsequently, this member can be automatically converted into surfaces (see Figure 01). Thus, the geometry is obtained as a surface model. Curved trapezoidal sheets are also possible. If a curved member is split into surfaces, it is represented by straight segments. If you still want to use curved lines, you can simply rotate the contour lines accordingly. The exact procedure can be found in the video.
AnswerThe detailed procedure can be found in the video. It indicates the most important features:
To ensure that the floor rests only on the downstand beam in this situation (Figure 1), it is recommended to model a minimum opening within the floor surface, see Figure 2.
In order to keep the members or the lines of the members integrated in the surface, the function "Connect Lines / Members" has to be applied to the entire model once. Thus, it is ensured that the floor slab continues to rest on the downstand beams.
The polyline displayed in Figure 1 was created in the order of Nodes 1 → 2 → 3 → 4 → 5. This is also visible in column B 'Node No.' Table '1.2 Lines'. Thus, the line segments between nodes 3, 4 and nodes 4, 5 are overlapping so that the error message in Figure 2 is displayed.
The order of the nodes must be changed so that no line segments could overlap. In this example, we want to specify the order of Nodes 1 → 2 → 3 → 5 → 4, as shown in Figure 3.
You can also use the 'Explode Polyline' function to decompose the polyline (Figure 4). Then, two lines are created between nodes 5 and 4. Then, delete a line. You can also use the 'Regenerate Model' function in the 'Tools' menu.
Both approaches are demonstrated in the video.
The plasticity for 1D elements currently only works in relation to the normal stresses in a member. This means that only interaction between axial force and moment is possible. The shear force interaction is not taken into account. In addition, the stresses from shear force are only calculated elastically.
When applying a plastic material model, it is also important to ensure a sufficient division of the elements, because a cross-section is internally generated at each Gauss point on the member element where the stress is calculated and a reduction of the stiffness to the re-distribution of the internal forces is performed, if necessary. If, for example, the number of divisions is increased, the model may become unstable because the redistributions of stresses can no longer be carried out and thus the cross-section's loading is too high.
It is generally recommended to use a division of '50' for member elements when using the plastic material model (see the figure).
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.
Your support is by far the best
“Thank you very much for the useful information.
I would like to pay a compliment to your support team. I am always impressed how quickly and professionally the questions are answered. In the industry of structural analysis, I use several software including service contract, but your support is by far the best.”