Failing to converge

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Failing to converge

Postby yingying » Thu Jan 11, 2018 5:51 am

I am running two earthquakes on a model simulating an earth dam. The first earthquake is shorter and has smaller accelerations, this runs fine. However when I run the second earthquake, it fails to converge:

WARNING: CTestNormDispIncr::test() - failed to converge
after: 30 iterations current Norm: 6.7019e-005 (max: 5e-005, Norm deltaR: 2899.44)
NewtnRaphson::solveCurrentStep() -the ConvergenceTest object failed in test()
DirectIntegrationAnalysis::analyze() - the Algorithm failed at time 10.92
OpenSees > analyze failed, returned: -3 error flag

When I increase the NormDispIncr iterations from 30 to 100, the model fails to converge at a later time (40secs rather than 10.92secs, the total length of the earthquake is 60secs). When I change the iterations to 200, it once again fails to converge at 40secs.

WARNING: CTestNormDispIncr::test() - failed to converge
after: 200 iterations current Norm: 0.000124496 (max: 5e-005, Norm deltaR: 4679.25)
NewtnRaphson::solveCurrentStep() -the ConvergenceTest object failed in test()
DirectIntegrationAnalysis::analyze() - the Algorithm failed at time 40.02
OpenSees > analyze failed, returned: -3 error flag
-3
OpenSees >

What could be the possible causes of this and how can i fix this?
yingying
 
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Location: university of Bath

Re: Failing to converge

Postby fmk » Thu Jan 11, 2018 10:25 am

NewtonRaphson does not always converge .. try something other than just increaing the number of iterations!

http://opensees.berkeley.edu/wiki/index ... ple3.3.tcl
fmk
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Joined: Fri Jun 11, 2004 2:33 pm
Location: UC Berkeley

Re: Failing to converge

Postby selimgunay » Fri Jan 12, 2018 6:57 pm

You can use the adaptive solution strategy below.

set Tol 1.0e-8;
set maxNumIter 100;
set printFlag 0;
set NewmarkGamma 0.5;
set NewmarkBeta 0.25;
set TestType EnergyIncr;

set algorithmType NewtonLineSearch;
for {set ik 1} {$ik <= $Nsteps} {incr ik 1} {
puts "$ik"
# puts "$ik"
set ok [analyze 1 $dtForAnalysis]
# Convergence
if {$ok != 0} {
puts "Trying Bisection ...";
algorithm NewtonLineSearch <-type Bisection>;
set ok [analyze 1 $dtForAnalysis]
algorithm $algorithmType;
};
if {$ok != 0} {
puts "Trying Secant ...";
algorithm NewtonLineSearch <-type Secant>;
set ok [analyze 1 $dtForAnalysis]
algorithm $algorithmType;
};
if {$ok != 0} {
puts "Trying RegulaFalsi ...";
algorithm NewtonLineSearch <-type RegulaFalsi>;
set ok [analyze 1 $dtForAnalysis]
algorithm $algorithmType;
};
if {$ok != 0} {
puts "Trying KrylovNewton ...";
algorithm KrylovNewton;
set ok [analyze 1 $dtForAnalysis]
algorithm $algorithmType;
};
if {$ok != 0} {
puts "Trying Newton ...";
algorithm Newton;
set ok [analyze 1 $dtForAnalysis]
algorithm $algorithmType;
};
if {$ok != 0} {
puts "Trying BFGS ...";
algorithm BFGS;
set ok [analyze 1 $dtForAnalysis]
algorithm $algorithmType;
};
if {$ok != 0} {
puts "Trying Broyden ...";
algorithm Broyden;
set ok [analyze 1 $dtForAnalysis]
algorithm $algorithmType;
};
if {$ok != 0} {
puts "Trying HHT 0.9 ...";
integrator HHT 0.9;
set ok [analyze 1 $dtForAnalysis]
# integrator TRBDF2;
integrator Newmark $NewmarkGamma $NewmarkBeta;
};
if {$ok != 0} {
puts "Trying OS ...";
integrator AlphaOS 1.00;
algorithm Linear;
set ok [analyze 1 $dtForAnalysis]
# integrator TRBDF2;
integrator Newmark $NewmarkGamma $NewmarkBeta;
algorithm $algorithmType;
};
if {$ok != 0} {
puts "Trying OSG ...";
integrator AlphaOSGeneralized 1.00;
algorithm Linear;
set ok [analyze 1 $dtForAnalysis]
# integrator TRBDF2;
integrator Newmark $NewmarkGamma $NewmarkBeta;
algorithm $algorithmType;
};
if {$ok != 0} {
puts "Trying more iterations...";
test $TestType $Tol 1000 $printFlag;
set ok [analyze 1 $dtForAnalysis]
test $TestType $Tol $maxNumIter $printFlag;
};
if {$ok != 0} {
puts "Trying tolerance 1.0e-7 ...";
test $TestType 1.0e-7 $maxNumIter 0;
set ok [analyze 1 $dtForAnalysis]
test $TestType $Tol $maxNumIter $printFlag;
};
if {$ok != 0} {
puts "Trying tolerance 1.0e-6 ...";
test $TestType 1.0e-6 $maxNumIter 0;
set ok [analyze 1 $dtForAnalysis]
test $TestType $Tol $maxNumIter $printFlag;
};
if {$ok != 0} {
puts "Trying tolerance 1.0e-5 ...";
test $TestType 1.0e-5 $maxNumIter 0;
set ok [analyze 1 $dtForAnalysis]
test $TestType $Tol $maxNumIter $printFlag;
};
if {$ok != 0} {
puts "Trying tolerance 1.0e-3 ...";
test $TestType 1.0e-3 $maxNumIter 0;
set ok [analyze 1 $dtForAnalysis]
test $TestType $Tol $maxNumIter $printFlag;
};
if {$ok != 0} {
puts "Trying tolerance 1.0e-3 ...";
test $TestType 1.0e-3 $maxNumIter 0;
set ok [analyze 1 $dtForAnalysis/2.0]
test $TestType $Tol $maxNumIter $printFlag;
};
if {$ok != 0} {
puts "Trying tolerance 1.0e-3 ...";
test $TestType 1.0e-3 $maxNumIter 0;
set ok [analyze 1 $dtForAnalysis/4.0]
test $TestType $Tol $maxNumIter $printFlag;
};
if {$ok != 0} {
puts "Trying tolerance 1.0e-3 ...";
test $TestType 1.0e-3 $maxNumIter 0;
set ok [analyze 1 $dtForAnalysis/8.0]
test $TestType $Tol $maxNumIter $printFlag;
};
if {$ok != 0} {
puts "Trying tolerance 1.0e-3 ...";
test $TestType 1.0e-3 $maxNumIter 0;
set ok [analyze 1 $dtForAnalysis/16.0]
test $TestType $Tol $maxNumIter $printFlag;
};
if {$ok != 0} {
puts "Trying tolerance 1.0e-3 ...";
test $TestType 1.0e-3 $maxNumIter 0;
set ok [analyze 1 $dtForAnalysis/32.0]
test $TestType $Tol $maxNumIter $printFlag;
};
if {$ok != 0} {
puts "Trying tolerance 1.0e-3 ...";
test $TestType 1.0e-3 $maxNumIter 0;
set ok [analyze 1 $dtForAnalysis/64.0]
test $TestType $Tol $maxNumIter $printFlag;
};





if {$ok != 0} {
set Nstepsmax [expr $ik-1]
break;
}

}

if {[expr $ik-1] == $Nsteps} {

set AnalysisA [expr 1] } else {

set AnalysisA [expr 0] };

puts "Analysis completion=$AnalysisA"

set fileid10 [open "ConvergenceIndicator.txt" a];
puts $fileid10 "$AnalysisA"
close $fileid10
selimgunay
 
Posts: 400
Joined: Mon Sep 09, 2013 8:50 pm
Location: University of California, Berkeley


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