ProfileSPDLinDirectSolver::solve() - error

[barkhordari]

can any body tell me what does this error means:
ProfileSPDLinDirectSolver::solve() - aii < 0 (i, aii): (0, 0)
WARNING NewtonRaphson::solveCurrentStep() -the LinearSysOfEqn failed in solve()
DirectIntegrationanalysis: : analyze<>- the algorithm failed at time 500

http://s6.picofile.com/file/8230569876/Capture.GIF

[Jeena]

Hi,

Can you share some more details about your model ? Is it a large model ?

I have seen similar error messages when there is an error in the modeling part - like inadequate number of supports or nodes without being connected to any elements etc ... Did you do a simple modal analysis (eigen analysis) to check the period of vibrations or mode shapes of the system ?? If your stiffness matrix is not formed properly, then you will see an error in the eigen value analysis itself ...

Thanks,
Jeena

[fmk]

if time 500 is the first step the model is probbably incorrect. if 500 is not the first step the tangent matrix is no longer symmetric positive definite, a 0 or a non negaive number has popped up on a diagonal during factorization. a different solver that does not require a positive definite matrix may work providing a mechanism has not formd in your model