Force applied on RBE3 element is not being translated to ANSYS structural

ANuser99
ANuser99 Altair Community Member
in Community Q&A

I have a model with 2D SHELL181 elements and i need to apply load on the surface. I have created an RBE3 element to apply load on the node. However when I export it to ANSYS the forces are being shown but the force is not being applied to the node in ANSYS. (I have checked the documentation where RBE3 elements are considered as CP equations and not elements in ANSYS)

Answers

  • Michael Herve
    Michael Herve
    Altair Employee

    hello @Anuser99,

    This may be related to definition of RBE3 in Ansys. Here's n extract of Ansys help:

    RBE3 distributes the force/moment applied at an independent node to a set of dependent nodes, taking into account the geometry of the dependent nodes as well as weighting factors. The force is distributed to the dependent nodes proportional to the weighting factors. The moment is distributed as forces to the dependent nodes; these forces are proportional to the distance from the center of gravity of the dependent nodes times the weighting factors. Only the translational degrees of freedom of the dependent nodes are used for constructing the constraint equations. Constraint equations are converted to distributed forces/moments on the dependent nodes during solution.

    RBE3 creates constraint equations such that the motion of the independent node is the average of the dependent nodes. For the rotations, a least-squares approach is used to define the "average rotation" at the independent node from the translations of the dependent nodes. If the dependent nodes are colinear, then one of the independent node rotations that is parallel to the colinear direction cannot be determined in terms of the translations of the dependent nodes. Therefore, the associated moment component on the independent node in that direction cannot be transmitted. When this case occurs, a warning message is issued and the constraint equations created by RBE3 are ignored.

    Regards,

    Michael

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