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- 2002-12-14
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- 1970-1-1
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***WARNING: THE SYSTEM MATRIX HAS 2 NEGATIVE EIGENVALUES.
IN AN EIGENVALUE EXTRACTION STEP THE NUMBER OF NEGATIVE EIGENVALUES IS
EQUAL TO THE NUMBER OF EIGENVALUES BELOW THE CURRENT SHIFT POINT.
THIS MAY BE USED TO CHECK THAT EIGENVALUES HAVE NOT BEEN MISSED.
NOTE: THE LANCZOS EIGENSOLVER APPLIES AN INTERNAL SHIFT WHICH WILL
RESULT IN NEGATIVE EIGENVALUES.
IN A DIRECT-SOLUTION STEADY-STATE DYNAMIC ANALYSIS, NEGATIVE
EIGENVALUES ARE EXPECTED.
IN OTHER CASES, NEGATIVE EIGENVALUES MEAN THAT THE SYSTEM MATRIX IS NOT
 OSITIVE DEFINITE:
FOR EXAMPLE, A BIFURCATION (BUCKLING) LOAD MAY HAVE BEEN EXCEEDED.
NEGATIVE EIGENVALUES MAY ALSO OCCUR IF QUADRATIC ELEMENTS ARE
USED TO DEFINE CONTACT SURFACES.
对静力非二次单元, 出现负特征值, abaqus 如何处理并进行下一步求解的?请高手相助 |
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