As runtime error message of “Singular Jacobian Matrix” is a frequently asked question, this article is intended to explain the background and the meaning of it.
Reason of the error message #
The mathematical definition is that the mapping between the parametric and the physical coordinates of the element is not unique. In words it means that the element is highly distorted.
Error message in the middle of the calculation #
If the error message occurs in the middle of the calculation, the initial geometry of the element was regular but it had an excessive distortion during the deformation. It can happen only in geometrically nonlinear analysis. It is not simply a large deformation but a collapse of the element. Its reason can be that the whole structure or a part of that runs out of strength at the certain load level. To find its root cause, the option of “Store last increment only” is recommended to turn off and the deformed shape is suggested to investigate.
Error message in the very first iteration #
If the message occurs immediately in the very first iteration, the initial geometry of the element was already highly distorted. It can be a very sharp element due to any editing mistake. However, if the initial geometry of the element seems to be right, the occurrence of the error message must be a sign of a bug. AxisVM generates a lot of elements in the background for the calculation model. E.g. spring elements for nonlinear Winkler or Winkler-Pasternak supports, rigid elements for the offset of eccentric domains. Any of them might be distorted, because of a bug. https://axisvm.atlassian.net/servicedesk/customer/portals
