I used two plastic material behavior curves and the solver finishes for the one which seems a bit stiffer, but an error message(Shown below) pop out for the other one. What do yo think is the reason and how can I avoid such things? I have used the same loading condition and step for both cases. I am expecting the solver to converge until the maximum stress, which then after the stiffness of the whole model will have a negative slope. I have attached the curves picture file.
Error message:
"Time increment required is less than the minimum specified"
Thank you for your help.
Look closer at the model - is there a stress concentration or so somewhere that causes the structure to fail locally?
Sometimes it also helps to increase the number of iterations in the newton solver (controls, analysis=discontinuous) or to switch to dynamic, quasistatic analysis.
Are you using same mesh size and density of the mesh. Because, the mesh size also influences the final results. I think limiting stiffness is defined as different. Also, you check the convergence criteria is satisfied or not..try your best..
Karthigeyan. thanks for your suggestion. But yes I have used EVERYTHING the same, except the material property inputs.(Just Copied and changed the result.
One thing I missed on my question is that there were such error messages before the above message.
"The strain increment has exceeded fifty times the strain to cause first yield at 319 points."
Looking to hear from you.
So one of your materials is probably softer than the other and you may reach a point where it is simply too soft to bear the load. Is the model displacement-controlled or force-controlled? If the latter, it may simply happen that your material cannot harden suffciently.
- Thank you Martin, the model is displacement controlled, and as you can see the black line is a bit stiffer -- Less strain with the same stress induced- before reaching to the maximum stress.
- If it is the case shouldn't I be having a maximum stress- breaking point(Or at lease the negative slop starting point?)
- My guess was that the lower the slop the lower the step increment needed for it not to exceed the maximum allowable strain per unit step. But still I decreased and still didn't help. Still confused.
Look closer at the model - is there a stress concentration or so somewhere that causes the structure to fail locally?
Sometimes it also helps to increase the number of iterations in the newton solver (controls, analysis=discontinuous) or to switch to dynamic, quasistatic analysis.
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