Warning 5628 and 312

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

Hi there, 

 

I am trying to run a simulation to produce an analysis on the chassis of a car (stress, strain, disp etc). I have tried to make the model as accurate as possible by applying all relevant loads. However, when I run Optistruct it says the following;

 

*** WARNING # 5628
 The compliance is negative or large 6.83807e+015.
 The rotational displacement has large magnitude, 5.82769e+009 degrees (larger than 180).
 The rotational degree of freedom may not be constrained properly in the model.
      subcase id = 4
         grid id = 187
       component = 4

 *** WARNING # 312
 In static load case 4
 the compliance is negative or large 6.83807e+015.
 Optimization/buckling analysis cannot be performed.
 due to possible rigid body mode.

 

I believe this is due to the model being under-constrained? (Please correct me if I'm wrong), however, I'm not sure where I can reduce the DOF without overly constraining the model. 

 

The model is attached. Any help is greatly appreciated,

 

Cheers, Laura

Unable to find an attachment - read this blog

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited May 2018

    Hi,

     

    I observed that you are constraining the nodes where you apply load and the direction is also same. 

     

    This is not valid.

     

    Release the Dof in the load application directions on the nodes and check if that helps. 

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