【讨论】关于负特征值问题的疑问

silt

***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  
    &nbspOSITIVE 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

silt

在刚度矩阵的特征值由正到零再到负的过程中，数值计算会出现病态，我关心ABAQUS如何处理这一问题的？
  
我想高手肯定也遇到负特征值问题，没有关心这一问题的？