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Failed to compute elasto-plastic variables
Posted 9 déc. 2010, 12:12 UTC−5 Materials, Structural Mechanics Version 3.5a, Version 4.1 4 Replies
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Hello,
I'm trying to solve an Structural Mechanics problem in 3D:
In fact, it's a concrete block that will be loaded in compression. I have introduced a Drucker Prager model defined by the equation:
F = alpha*Tr_s+sigma_eqv-K;
where,
alpha = (fc-ft)/(fc+ft)
Tr_s = sx_smsld+sy_smsld+sz_smsld
sigma_eqv = sqrt(0.5*(sx^2+sy^2+sz^2)+sxy_smsld^2), et
k = 2*(fc*ft)/(fc+ft)
I have introduced the subdomain expressions fc and ft and defined the function "Disp" (displacement) as follows:
0 0
0.5 0.0005
0 0.001
to define an prescribed displacement of 1 mm.
I'm trying to solve this problem as a time-dependent function but the solution doesn't converge. I have always the Error message:
Error: 8030
Subdomain plot failed.
Failed to compute elasto-plastic variables, try instead the Gauss-point variables.
I'm working in the 35a version of COMSOL and I would like to solve this problem before passing to the most recent version of COMSOL.
If someone has had a similar problem before or know the answer for this kind of problem I would really appreciate her/his help.
Thanks in advance,
Angel
I'm trying to solve an Structural Mechanics problem in 3D:
In fact, it's a concrete block that will be loaded in compression. I have introduced a Drucker Prager model defined by the equation:
F = alpha*Tr_s+sigma_eqv-K;
where,
alpha = (fc-ft)/(fc+ft)
Tr_s = sx_smsld+sy_smsld+sz_smsld
sigma_eqv = sqrt(0.5*(sx^2+sy^2+sz^2)+sxy_smsld^2), et
k = 2*(fc*ft)/(fc+ft)
I have introduced the subdomain expressions fc and ft and defined the function "Disp" (displacement) as follows:
0 0
0.5 0.0005
0 0.001
to define an prescribed displacement of 1 mm.
I'm trying to solve this problem as a time-dependent function but the solution doesn't converge. I have always the Error message:
Error: 8030
Subdomain plot failed.
Failed to compute elasto-plastic variables, try instead the Gauss-point variables.
I'm working in the 35a version of COMSOL and I would like to solve this problem before passing to the most recent version of COMSOL.
If someone has had a similar problem before or know the answer for this kind of problem I would really appreciate her/his help.
Thanks in advance,
Angel
4 Replies Last Post 30 juin 2011, 06:49 UTC−4
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Posted:
1 decade ago
Hi
I havent gone far into your model but I'm puzzled about: 1)
sigma_eqv = sqrt(0.5*(sx^2+sy^2+sz^2)+sxy_smsld^2), et
shoulnt it be ?
sigma_eqv = sqrt(0.5*(sx_smsld^2+sy_smsld^2+sz_smsld^2)+sxy_smsld^2), et
then I suspect k is already defined in COMSOl so there might be a little naming mess, try avoid single lettre variables for you own variables, I thendto add a _ or _ik to my variables to clearly identify them
--
Good luck
Ivar
I havent gone far into your model but I'm puzzled about: 1)
sigma_eqv = sqrt(0.5*(sx^2+sy^2+sz^2)+sxy_smsld^2), et
shoulnt it be ?
sigma_eqv = sqrt(0.5*(sx_smsld^2+sy_smsld^2+sz_smsld^2)+sxy_smsld^2), et
then I suspect k is already defined in COMSOl so there might be a little naming mess, try avoid single lettre variables for you own variables, I thendto add a _ or _ik to my variables to clearly identify them
--
Good luck
Ivar
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Posted:
1 decade ago
Hi Ivar,
firstly, thank you very much for your answer.
To define sigma_eqv I had previously defined sx, sy and sz as follows:
sx = sx_smsld-sigma_mean,
sy = sy_smsld-sigma_mean,
sz = sz_smsld-sigma_mean, and
sigma_mean = (sx_smsld+sy_smsld+sz_smsld)/3
Apparently the equations are well introduced, anyway I tried to make the change that you suggested me but it doesn't work not either.
The problem is that the model doesn't arrive to converge because of some Error in residual computation.
Besides en the error message they suggest me to try instead the Gauss-point variables, but it doesn't work.
I would really appreciate any kind of help or suggestion that you could give me to solve this problem.
Angel
firstly, thank you very much for your answer.
To define sigma_eqv I had previously defined sx, sy and sz as follows:
sx = sx_smsld-sigma_mean,
sy = sy_smsld-sigma_mean,
sz = sz_smsld-sigma_mean, and
sigma_mean = (sx_smsld+sy_smsld+sz_smsld)/3
Apparently the equations are well introduced, anyway I tried to make the change that you suggested me but it doesn't work not either.
The problem is that the model doesn't arrive to converge because of some Error in residual computation.
Besides en the error message they suggest me to try instead the Gauss-point variables, but it doesn't work.
I would really appreciate any kind of help or suggestion that you could give me to solve this problem.
Angel
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Posted:
1 decade ago
Hi
unfotunately I do not have any other ideas to propose like that, the sx looked like strange, but if these are defined variables, now sx is also used internally, perhaps to be on the sure side, try to avoid simple names or personalise your variables fully
--
Good luck
Ivar
unfotunately I do not have any other ideas to propose like that, the sx looked like strange, but if these are defined variables, now sx is also used internally, perhaps to be on the sure side, try to avoid simple names or personalise your variables fully
--
Good luck
Ivar
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hi Ivar,
firstly, thank you very much for your answer.
To define sigma_eqv I had previously defined sx, sy and sz as follows:
sx = sx_smsld-sigma_mean,
sy = sy_smsld-sigma_mean,
sz = sz_smsld-sigma_mean, and
sigma_mean = (sx_smsld+sy_smsld+sz_smsld)/3
Apparently the equations are well introduced, anyway I tried to make the change that you suggested me but it doesn't work not either.
The problem is that the model doesn't arrive to converge because of some Error in residual computation.
Besides en the error message they suggest me to try instead the Gauss-point variables, but it doesn't work.
I would really appreciate any kind of help or suggestion that you could give me to solve this problem.
Angel
Hi Angel,
I am having a similar problem with the version 4.1. Did you solve the problem? Do you have any idea how to get the variables at Gauss-points? Thanks!