Learning Forum

[PiotrM]

Hey

I have a problem with Static Structural analysis. I have two pipes connected with bolts. Boundary conditions: one end is fixed, on the other end is bending moment.

The problem starts when I change the mesh from 1 order elements to 2 order elements. For 1 order elements, the analysis is done. For 2 order elements the analysis does not go and shows an error:

"The preconditioned conjugate gradient solver failed with an error code of 1. Please check for an insufficiently constrained model. Switching to the sparse direct solver may allow this nonlinear analysis to continue beyond this point. "

I do not change anything outside the mesh: order of elements. Solver is set to program controlled. Changing for direct also fails due to lack of memory.

[Ashish Khemka]

nnCan you try using an iterative solver? The direct solver may take more memory and you will get insufficient disk space error. For an insufficiently constrained model - please see if the results of the first analysis look fine, i.e., the model is behaving as expected.nnRegards,nAshish Khemkan

[PiotrM]

Hi ArraynThanks for the answer.nThe 1-order model works and look fine. There is not problem with solving. nFor more accuracy, I wanted to use 2 order elements because: 1 order elements: The element may not offer sufficient accuracy for bending-dominant problems, especially if the mesh is not fine enough. n

[PiotrM]

Any suggestion or explanation why the 2 order model shows instability over the 1 order?n