« Return to Thread: zero Force everywhere!!
RE: stress relaxation problem...
by Alberto Echeverria
::
Rate this Message:
Dear Fatih,
I think you should read about how to do a creep analysis. If you apply a
creep type law (There are different models depending on the creep mechanism,
Norton , time hardening, strain hardening ) for your material under
prescribed strain conditions you will see that elastic strain will transform
into creep strain and this way the stress (dependent on the elastic strain)
will decrease.
I remember that you ought to use *Visco kind of analysis.
I cannot remember if there are examples, please check the documentation.
Kind regards,
Alberto
De: Abaqus@... [mailto:Abaqus@...] En nombre de
aruk77500
Enviado el: miércoles, 01 de julio de 2009 13:20
Para: Abaqus@...
Asunto: [Abaqus] stress relaxation problem...
hello group,
I need to take idea of you about a problem.
I want to make a stress relaxation analysis of PA6. Let's say a polymer rod
is pretensioned by applyling a strain. And then, I want to calculate the
time required for the stress to come below a certain limit under this
constant strain.
What kind of analysis should I carry? A general static step to apply the
pretension and then what? a visco analysis? What kind of material behaviour
should I use for such a problem? What are the outputs in Abaqus I should
check? Is there a smiler problem in Abaqus documentation?
Thank you very much for your taking the time.
fatih
--- In Abaqus@... <mailto:Abaqus%40yahoogroups.com> , "Steve
Manifold" <s.manifold@...> wrote:
>
>
>
> So if you invert 1e+06 you get 1e-06. This is too small for modern
> computers?
>
>
>
>
>
> From: Abaqus@... <mailto:Abaqus%40yahoogroups.com>[mailto:Abaqus@... <mailto:Abaqus%40yahoogroups.com> ] On Behalf
Of
> krobkrobkrob
> Sent: Thursday, June 25, 2009 7:33 PM
> To: Abaqus@... <mailto:Abaqus%40yahoogroups.com>
> Subject: [Abaqus] Re: zero Force everywhere!!
>
>
>
>
>
>
>
>
> You might want to recheck your units.
>
> Also, your entries for loads are expanded to, for example, "e+06" which I
> assume would be newtons. This expansion makes your numbers very large. If
> the calculation involves inverting at some point, you are bound to end up
> with very tiny numbers, which could easily be declared to be zero during
> computation!
>
> Regards,
> Robert
>
> --- In Abaqus@... <mailto:Abaqus%40yahoogroups.com><mailto:Abaqus%40yahoogroups.com> , ziyad
> <ziyad02@> wrote:
> >
> >
> > Hi all,
> > I had recieved following warrning when modeling load test on board pile.
> Has
> > anyone an idea what does this mean. Attached inp.file.
> >
> > regards
> > Ziyad
> >
> > warrning:"There is zero FORCE everywhere in the model based on thedefault
> > criterion. please check the value of the average FORCE during the
current
> > iteration to verify that the FORCE is small enough to be treated as
zero.
> if
> > not, please use the solution controls to reset the criterion for zero
> > FORCE." http://www.nabble.com/file/p24147811/Load-test.inp Load-test.inp
> > --
> > View this message in context:
> http://www.nabble.com/zero-Force-everywhere%21%21-tp24147811p24147811.html
> > Sent from the Abaqus Users mailing list archive at Nabble.com.
> >
>
>
>
>
>
> [Non-text portions of this message have been removed]
>
[Non-text portions of this message have been removed]
I think you should read about how to do a creep analysis. If you apply a
creep type law (There are different models depending on the creep mechanism,
Norton , time hardening, strain hardening ) for your material under
prescribed strain conditions you will see that elastic strain will transform
into creep strain and this way the stress (dependent on the elastic strain)
will decrease.
I remember that you ought to use *Visco kind of analysis.
I cannot remember if there are examples, please check the documentation.
Kind regards,
Alberto
De: Abaqus@... [mailto:Abaqus@...] En nombre de
aruk77500
Enviado el: miércoles, 01 de julio de 2009 13:20
Para: Abaqus@...
Asunto: [Abaqus] stress relaxation problem...
hello group,
I need to take idea of you about a problem.
I want to make a stress relaxation analysis of PA6. Let's say a polymer rod
is pretensioned by applyling a strain. And then, I want to calculate the
time required for the stress to come below a certain limit under this
constant strain.
What kind of analysis should I carry? A general static step to apply the
pretension and then what? a visco analysis? What kind of material behaviour
should I use for such a problem? What are the outputs in Abaqus I should
check? Is there a smiler problem in Abaqus documentation?
Thank you very much for your taking the time.
fatih
--- In Abaqus@... <mailto:Abaqus%40yahoogroups.com> , "Steve
Manifold" <s.manifold@...> wrote:
>
>
>
> So if you invert 1e+06 you get 1e-06. This is too small for modern
> computers?
>
>
>
>
>
> From: Abaqus@... <mailto:Abaqus%40yahoogroups.com>
Of
> krobkrobkrob
> Sent: Thursday, June 25, 2009 7:33 PM
> To: Abaqus@... <mailto:Abaqus%40yahoogroups.com>
> Subject: [Abaqus] Re: zero Force everywhere!!
>
>
>
>
>
>
>
>
> You might want to recheck your units.
>
> Also, your entries for loads are expanded to, for example, "e+06" which I
> assume would be newtons. This expansion makes your numbers very large. If
> the calculation involves inverting at some point, you are bound to end up
> with very tiny numbers, which could easily be declared to be zero during
> computation!
>
> Regards,
> Robert
>
> --- In Abaqus@... <mailto:Abaqus%40yahoogroups.com>
> <ziyad02@> wrote:
> >
> >
> > Hi all,
> > I had recieved following warrning when modeling load test on board pile.
> Has
> > anyone an idea what does this mean. Attached inp.file.
> >
> > regards
> > Ziyad
> >
> > warrning:"There is zero FORCE everywhere in the model based on the
> > criterion. please check the value of the average FORCE during the
current
> > iteration to verify that the FORCE is small enough to be treated as
zero.
> if
> > not, please use the solution controls to reset the criterion for zero
> > FORCE." http://www.nabble.com/file/p24147811/Load-test.inp Load-test.inp
> > --
> > View this message in context:
> http://www.nabble.com/zero-Force-everywhere%21%21-tp24147811p24147811.html
> > Sent from the Abaqus Users mailing list archive at Nabble.com.
> >
>
>
>
>
>
> [Non-text portions of this message have been removed]
>
[Non-text portions of this message have been removed]
« Return to Thread: zero Force everywhere!!
| Free embeddable forum powered by Nabble | Forum Help |
