Convergence issues spectific to Abaqus/Standard (Noncontact Related)
- Numerical Singularities
: These indicate that so many digits are lost during linear equation solution that the results are not reliable.
The most common cause is an unconstrained rigid body mode in a static stress analysis
e.g. 경계조건이 부족하여 rigid body mode 발생 (방정식 개수 < 미지수 개수)
- Zero Pivots
: These occur during linear equation solution when there is a force term but no corrensponding stiffness.
Common causes are unconstrained rigid body modes and overconstrained degrees of freedom
e.g. 경계조건 과다 (방정식 개수 > 미지수 개수)
- Negative eigenvalues
: Negative eigenvalues indicate that the stiffness matrix is not positive definite.
For example, a buckling load may have been exceeded.
e.g. 재질에서 좌굴이 발생할 소지가 있는지 확인 (|D|<0, 역행렬을 못 구함)
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