convergence error

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zeinab
Posts: 1
Joined: Sun Apr 22, 2012 2:11 am

convergence error

Post by zeinab » Sun Apr 22, 2012 3:37 am

I 'm studying on progressive collapse in moment frame
I encountered to some errors . the errors are :
1- WARNIG:CT NormDispIncr or ( Energy Incr) :: test - failed to converge after 100 iteration
2- (type of algorithm for example Newton):: solveCurrent step - the convergence object Test fail in Test
DirectIntegrationAnalisys :analyze- the algorithm fail at time 7.02
Although I tried to correct the errors by using the following instructions, the errors have not been corrected yet.
1- test :- NormDispIncr 10e-6 50 or100 or 150 or200
- EnergyIncr 10e-6 50 or100 or 150 or200

2-algorithm :I tried all kinds of algorithm that exist in manual

3-integrator - Newmark0.5 0.25
-HHT 0.5
some other information about analyze are as following:

test NormDispIncr 0.000001 100
algorithm Newton
numberer RCM
constraints Transformation
system BandGeneral
integrator Newmark 0.5 0.25
analysis VariableTransient
analyze 350 0.02;

set Time 7.5
remove element 2
remove element 7
remove node 2
remove node 112
analyze 650 0.02;

HOW CAN I CORRECT THESE ERRORS?
I really appreciate your help.
I am looking forward to hearing from you.

fmk
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Posts: 5866
Joined: Fri Jun 11, 2004 2:33 pm
Location: UC Berkeley
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Re: convergence error

Post by fmk » Wed May 02, 2012 3:56 pm

it's not an error .. it's your model and your script .. if you are having problems converging wit Newton, increasing the # of steps is not going to help, if initial stiffness iterations do not work and NewtonLineSearch fails, you might want to cut down on the time step or if you have a full mass matrix, use the CentralDifference method and an appropriatly chosen time step.

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