| E5005
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WARNING: E5005
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STIFFNESS MATRIX SINGULAR OR NON-POSITIVE DEFINITE
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Cause:
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A singularity or non-positive definite has been detected in the stiffness matrix during the preconditioning phase of the iterative solver in a nonlinear solution. Typically, this warning indicates that the current loading has resulted in an instability in the model, but may also indicate a problem with the element material property data. The stiffness matrix will be automatically updated again without differential stiffness (stiffness due to stress) and an
E5077 warning message will be issued. If after the second attempt the same error occurs, the solution will terminate with a fatal error,
E5004. One or more of the following may cause a non-positive definite during the nonlinear iteration:
- The number of load increments specified in field 3 of the
NLPARM Bulk Data entry is too small.
- The current loading is near the critical load of the structure (this may occur during equilibrium iterations even though the structure is not directly loaded in compression).
- The element nonlinear material properties have become invalid either because they were defined incorrectly as a result of one or more of the above conditions.
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Action:
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The stiffness matrix will be automatically updated again without the differential stiffness contribution. If a fatal error results, try one of the following:
- Increase the number of load increments specified in field 3 of the NLPARM Bulk Data entry, or divide the loading using several subcases.
- Reduce the applied loading.
- Investigate any nonlinear material properties (nonlinear elastic, thermo-elastic, elastic-plastic) that are specified.
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Remarks:
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None.
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