Repairing the instability of model

It may happen that the model is so defined that the numerical solution is impossible. Most often some kind of numerical instability may occur due to mistakes in the definition of boundary conditions.

Maximum displacement has been reached

The first case is that the numerical solution itself was correct, but the results seem to be distorted. This situation can be revealed by the check of maximum permissible vale of displacement and rotation. If the adjusted values are exceeded, a warning is given.

The results may be reviewed even if this situation happens. It is up to the user’s experience to decide whether the structure is so soft and the large deformation is reasonable or whether a mistake was made in the definition of the model.

The point where the maximum displacement has been found is stated in the warning dialogue.

Singular stiffness matrix

If the stiffness matrix is singular, the solution cannot be obtained at all. The user is informed about the problematic place in the model. The place is stated in the warning dialogue.

In case of linear analysis the singularity check is available. An animation window showing translations and rotations is immediately displayed.

Note: Since SCIA Engineer 19.0 singularity check is always automatically displayed when the stiffness matrix is singular.

The place of instability can be also marked with an arrow which can be displayed by means of View parameter settings - tab Misc.- Display arrow on maximal deformation.