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how to increase the number of cycles in piecewise function.

Sanjay Dakshinamoorthy

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i am doing thermal shock test of a sandwich model. using Piecewise function i have given the temperature profile for (-40 C 15min and 125 C 15min) .this is one cycle... in thermal stress...
now i wanted to increase the cycles to 500 or even 1000 cycles......
typing in picesewise function for 500 or 1000 cycles i a long time job....
is there any other way to give the no of cycles in input...

D.Sanjay,
b'lore.

9 Replies Last Post 2011年4月23日 GMT-4 03:06
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 2011年4月8日 GMT-4 01:50
Hi

but what do you expect to change between one cycle and 2, ...1000 ?
I would say rather calculate one cycle, and integrate manually whatever variable you have.

Now if this variable changing is influencing the calculations, you might manage to accumulate 100 cycles, then rerun with the new values, and accumulate again 100 cycles etc, this would cut down the calculation time, but I'm not sure it applies to your case ;)

--
Good luck
Ivar
Hi but what do you expect to change between one cycle and 2, ...1000 ? I would say rather calculate one cycle, and integrate manually whatever variable you have. Now if this variable changing is influencing the calculations, you might manage to accumulate 100 cycles, then rerun with the new values, and accumulate again 100 cycles etc, this would cut down the calculation time, but I'm not sure it applies to your case ;) -- Good luck Ivar

Sanjay Dakshinamoorthy

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Posted: 1 decade ago 2011年4月8日 GMT-4 03:02
thanks for the reply IVAN,

i am finding the creep taking place in the solder (sandwich model) due to the influence of temperature.
i have attached an example of results required .

regards,

D.Sanjay
thanks for the reply IVAN, i am finding the creep taking place in the solder (sandwich model) due to the influence of temperature. i have attached an example of results required . regards, D.Sanjay


Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 2011年4月8日 GMT-4 03:49
Hi

then probably you need to run N cycles within COMSOL, if you have not other way to separate the effects, as I see the stress changes, but the temperature cycle is probably not affected

--
Good luck
Ivar
Hi then probably you need to run N cycles within COMSOL, if you have not other way to separate the effects, as I see the stress changes, but the temperature cycle is probably not affected -- Good luck Ivar

Sanjay Dakshinamoorthy

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Posted: 1 decade ago 2011年4月8日 GMT-4 04:41

Hi

then probably you need to run N cycles within COMSOL, if you have not other way to separate the effects, as I see the stress changes, but the temperature cycle is probably not affected

--
Good luck
Ivar


thanks for the reply..
as i am new user to comsol... i wanted to know how to run N cycles.... in piecewise i could define only one cycle..
where can i define N cycles.. is there any tutorials for it..

d.sanjay
[QUOTE] Hi then probably you need to run N cycles within COMSOL, if you have not other way to separate the effects, as I see the stress changes, but the temperature cycle is probably not affected -- Good luck Ivar [/QUOTE] thanks for the reply.. as i am new user to comsol... i wanted to know how to run N cycles.... in piecewise i could define only one cycle.. where can i define N cycles.. is there any tutorials for it.. d.sanjay

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 2011年4月8日 GMT-4 04:46
Hi

no not really, make your load function periodical (in V4.1 you have an option in the analytical or piecewise functions somewhere ;) or use a modulo "t" and then run a long transient run

--
Good luck
Ivar
Hi no not really, make your load function periodical (in V4.1 you have an option in the analytical or piecewise functions somewhere ;) or use a modulo "t" and then run a long transient run -- Good luck Ivar

Sanjay Dakshinamoorthy

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Posted: 1 decade ago 2011年4月12日 GMT-4 00:40
Ivar,
with the help of piecewise function i have done single cycle. for running N cycles do i need any other software like MatLab or Comsol 4.0 itself can do it?
If Comsol 4.0 can do... can u help me in doing N cycles...

regards,
Sanjay.D
Ivar, with the help of piecewise function i have done single cycle. for running N cycles do i need any other software like MatLab or Comsol 4.0 itself can do it? If Comsol 4.0 can do... can u help me in doing N cycles... regards, Sanjay.D

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 2011年4月12日 GMT-4 02:19
Hi

if its a transient solver sequence, you need to make your cycle command periodic (repeating w.r.t. "t" time) you can use a modulo function, there are several threads thereon, try a search

--
Good luck
Ivar
Hi if its a transient solver sequence, you need to make your cycle command periodic (repeating w.r.t. "t" time) you can use a modulo function, there are several threads thereon, try a search -- Good luck Ivar

Sanjay Dakshinamoorthy

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Posted: 1 decade ago 2011年4月23日 GMT-4 02:21
Ivar,
i gave the piecewise function of one cycle i.e cycle finishing time is 900 s( 15min)
in the transient solver the time step is range(0,1,900)
if i increace the time in the solver for multiple cycles i.e (0,1,1800) i get solver error.
is there any way to cycle increase or do i need MATLAB or comsol can solve N cycles.?

regards,
SANJAY.D
Ivar, i gave the piecewise function of one cycle i.e cycle finishing time is 900 s( 15min) in the transient solver the time step is range(0,1,900) if i increace the time in the solver for multiple cycles i.e (0,1,1800) i get solver error. is there any way to cycle increase or do i need MATLAB or comsol can solve N cycles.? regards, SANJAY.D

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 2011年4月23日 GMT-4 03:06
Hi

make sure that your time cycle is
1) really periodic with a function plot, and that it's derivable (no sharp steps, particularly at the transition)
2) then use a transient solver (for all periodic type responses) with the time step set to strict or intermediate (check the doc)
Or at least set a few extra time steps at the transition to get the solver to reconsider the slope of you signal, else it might skip over the repetition (and fail)

--
Good luck
Ivar
Hi make sure that your time cycle is 1) really periodic with a function plot, and that it's derivable (no sharp steps, particularly at the transition) 2) then use a transient solver (for all periodic type responses) with the time step set to strict or intermediate (check the doc) Or at least set a few extra time steps at the transition to get the solver to reconsider the slope of you signal, else it might skip over the repetition (and fail) -- Good luck Ivar

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