| E5001 | FATAL ERROR: E5001 | NON-POSITIVE DEFINITE DETECTED AT GRID id COMPONENT n |
| Cause: | A negative term has been detected on the stiffness matrix factor diagonal during decomposition. | |
| Action: | Investigate the degree of freedom at which the non-positive definite condition occurred. Also, check the Solution Processor output in the Model Results Output File for degrees of freedom with large factor diagonal ratios. A large factor diagonal ratio may indicate a mechanism. Also, check your model for isolated large stiffnesses or too few constraints. If using shell elements, either set the K6ROT model parameter to a value between 1.0 and 100.0, or set the SHELLRNODE model parameter to ON. If this does not solve the problem or you are unable to locate the source of the singularity, consider setting the SOLUTIONERROR model parameter to ON. To bypass all error handling for this error, also set the FACTDIAG model parameter to zero. Note that solution accuracy may be degraded with the SOLUTIONERROR model parameter set to ON. Check the EPSILON value in the Model Results Output or Results Summary File. Values greater than 0.001 indicate a possible loss of accuracy. | |
| Remarks: | See Autodesk Nastran Reference Guide, Section 5, Parameters, for more information on the K6ROT, SHELLRNODE, and SOLUTIONERROR parameters. |