Negative or Large Compliance

Hello,

I am attempting to run an optimization using Optistruct but the solver keeps outputting the following error:

 

            *** ERROR # 312 ***
            In static load case 1
            the compliance is negative or large 1.7638e+015.
            Optimization/buckling analysis cannot be performed.
            due to possible rigid body mode.
            INFEASIBLE DESIGN (AT LEAST ONE CONSTRAINT VIOLATED).

 

From what I understand, this error could be from a model that is not fully constrained or from poorly defined materials properties. My model is constrained with 2 RBE3 elements so I believe my constraints are not the issue and I don't understand what could be wrong with my material inputs. 

 

I have attached my model for reference. Any help would be appreciated

 

Thanks

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