Error while using integrator CentralDifference

[keqiliu]

I have built a simple model using CentralDifference to integrator, and it is statically determinate, but the opensees showing error that


WARNING: CentralDifference::domainChanged() - assuming Ut-1 = Ut
WARNING BandSPDLinLapackSolver::solve() - the LAPACK routines returned 5
WARNING Linear::solveCurrentStep() -the LinearSOE failed in solve()
DirectIntegrationAnalysis::analyze() - the Algorithm failed at time 0
OpenSees > analyze failed, returned: -3 error flag
-3


The model is as follows,

wipe ;
model basic -ndm 2 -ndf 2

node 1 0.0 0.0
node 2 0.1 0.0
node 3 0.1 0.3 -mass 0.9 0.9
node 4 0.0 0.3 -mass 0.9 0.9

fix 1 1 1
fix 2 0 1

nDMaterial ElasticIsotropic 1 2.8e10 0.3
element quad 1 1 2 3 4 0.1 PlaneStress 1 ;

pattern Plain 1 {Series -time {0.0 0.01 0.02} -values {0.0 1.0 0.0} } {
load 3 0.0 100000
load 4 0.0 100000
}
constraints Plain;
numberer RCM;
system BandSPD;
test NormDispIncr 1.e-8 25 2;
algorithm Linear;
integrator CentralDifference;
analysis Transient;
analyze 1000 0.0000002;

[fmk]

you need a mass at node 2 in x direction .. mass matrix will have a 0 on diag for that entry which is why solver fails as matrix singular.

[keqiliu]

Thanks fmk. It solved my question.