DSC algorthm get a mistake with Instability Type 3?

[NguyenTTU]

Hi,

I have a model as the attachment. This model is definitely stable in both directions, however I try analysing this model in 2 cases of DSC algorithm with automatic method of solving the system.

Case 1: As the attachment, it is instability (type 3) in the UX direction.

Case 2: It is a good structure without instability.

I try to analyse with other methods, it gave me the same results.

My question is could DSC algorthm have a problem to recognise instability problem?

Best Regards

Tu Nguyen

[Rafal.Gaweda]

Use all other solvers than Sparse.

http://forums.autodesk.com/t5/robot-structural-analysis/solvers/m-p/3759454/highlight/true#M10124

http://forums.autodesk.com/t5/robot-structural-analysis/instability-in-node-46-in-direction-ux/m-p/4...