how to solve incompatible kinematic

Altair Forum User
Altair Forum User
Altair Employee
edited October 2020 in Community Q&A

dear all

       how to solve incompatible kinematic? there is a warning when I make crash analysis.

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited July 2016

    Hi,

     

    Check where exactly this is coming from.

     

    If it has something to do with constraints, remove the Dof for that particular constraint(s)

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited July 2016

    Hi,

    As nodal constraints are based on kinematic conditions applied on nodal DOF, therefore it is not allowed to apply two nodal constraints to the same set of nodes. RADIOSS Starter will issue the following warning each time two nodal constraints are applied to the same set of nodes.

    This is an undesired warning in a model. It is of very important to take all warnings about incompatible kinematic conditions into account. True incompatible kinematic conditions can generate energy and local instability. In such a case, accuracy of the results will be seriously decreased.

    Check the model and find where the nodes are over constrained or where the constraints are violating the loads applied.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited July 2016
    Altair Forum User said:

    Hi,

     

    Check where exactly this is coming from.

     

    If it has something to do with constraints, remove the Dof for that particular constraint(s)

    thanks!

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited July 2016
    Altair Forum User said:

    Hi,

    As nodal constraints are based on kinematic conditions applied on nodal DOF, therefore it is not allowed to apply two nodal constraints to the same set of nodes. RADIOSS Starter will issue the following warning each time two nodal constraints are applied to the same set of nodes.

    This is an undesired warning in a model. It is of very important to take all warnings about incompatible kinematic conditions into account. True incompatible kinematic conditions can generate energy and local instability. In such a case, accuracy of the results will be seriously decreased.

    Check the model and find where the nodes are over constrained or where the constraints are violating the loads applied.

    Thanks for your patience!  I will check my model.

  • harshitpuri
    harshitpuri Altair Community Member
    edited July 2016

    Check your boundary condition

    have you applied them on rigid nodes also?

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