Element formulations and model types in RFEM 6

Students & Education
, ,
1

As part of a project work for my master's degree in civil engineering, I am dealing with the calculation of surface structures (discs and plates). For this purpose, I have some questions about the element types used in RFEM:

Could you please explain which element formulations RFEM uses by default? Are they primarily isoparametric, non-conforming, or hybrid elements?

On the Dlubal website, I found information about MITC3+ (triangles) and MITC4 (quadrilaterals). Since these elements also have rotational degrees of freedom, the following question arises regarding the modeling of pure plates:

Do I understand correctly that I model a "real" plate correctly by choosing the model type 2D | XZ | stress in plane? Does this deactivate the rotational degrees of freedom (bending) typical for shell MITC elements so that only the forces of a plate are effective?

Thank you in advance for your support.

3

Hello @KujAl,
welcome to the Dlubal Community! :tada:

In the model type "Stress in Plane," the degrees of freedom out of the plane (u_z) as well as the rotations (\phi_x, \phi_y, \phi_z) are disabled. The MITC elements are reduced purely to their membrane parts in this mode. The bending stiffness of the elements does not come into play at all because the corresponding deformations are mathematically locked. The element then acts purely as a membrane element.
Effects from bending theory are thus excluded because the stiffness matrix of the overall system only considers the components for the planar stress state.

Thus, this model type exactly represents a 'true' plate in the sense of mechanics.
More information about the finite elements used can be found here: Finite Elemente in RFEM

Best regards,
Rebecca Göbel

2 Likes