I have to model element dropping ,so I try twoNodeLink element. I built a model with a dispbeamcolumn element in the middle and two zero length twoNodeLink elements in each end. Like :
1 101 202 2
From 1 to 101 ,202 to 2 are the twoNodeLink elements,which are removed later.From 101 to 202 is the dispbeamcolumn element, which is suffering gravity droping when all the two ends has been removed.
When I remove a single elemnt of the ends ,it runs well ,but if I remove all the elements of the two ends ,it couldn't go. It reflects information like " lapack routine returned 506 ;analyze failed ,returned -3 flag" or "matrix is singular. only 518 pivots found" when I tried Umfpack as system option. Can anybody tell me why? Can the zero length twoNodeLink element be removed ? I defined the dispbeamcolumn element by using same coordinates with the end nodes .
Thanks for advance!