I am modelling tensile shear test of GFRP Composite with Hashin Damage in ABAQUS. Model with Damage Initiation alone (without Evolution) converges, when NLGEOM is OFF. But with Damage Evolution Criteria, it is not Converging. I tried Damage Stabilisation, but it works only for higher values (0.01) and it gives erratic results. When i turn ON NLGEOM, none of them is converging.
Errors i get are: Too many attempts made for this increment, Time Required is less than Minimum Value.
Warnings are: FORCE equilibrium accepted using the alternate tolerance.
I have Half Symmetric Model (Composite Layup with Conventional Shell) and applied Displacement BC(U1 Specified, Others are Zero) on end of the Plate and have Encastre BC on Pin(Rigid Body) at the Hole. Node to Surface Contact with Small Sliding is used with Pin (Surface) has Master and Plate (Nodes) as Slave.
Step: Initial – 0.01, Minimum – 1e-9
Material Properties: Lamina, E1:35000 N/mm2, E2:2432, Nu12:0.32, G12,G13:1057, G23: 863, Hashin Damage, YLT:1652, YLC:740, YTT:26, YTC:36, SL:31, ST:31, Evolution, LT:1.26 N/mm, LC:0.25, TT:0.0068, TC:0.0135.
I have Fine Mesh around the Hole (as i want to introduce micromechanical Properties in to the model later).
Tried the Model in Dynamic, Implicit (Quasi Static) - Not Working.
Dynamic, Explicit - Model converges with deletion of elements due to Damage. But I read that it is not advisable to use Explicit and dont know how to choose the Optimal value of Mass scaling factor.
Please suggest me, how to deal with these Convergence issues and how to choose the correct value for Damage Stabilisation..
I have attached images for reference.
HI, if you clearly observe your error message "Too many attempts made for this increment, Time Required is less than Minimum Value".
To avoid this type of errors you need to change some parameters in Steps. The solver need more increments to converge. Try changing the variables in the steps.
Keep NLGEOM on
Time period=1
Number of increments=100000
Increment size: Initial=0.001
Min=1x10-30
Try changing the control parameters sounds like you have specified the min value to be too big or try using a smaller min value.
In Abaqus Standard/Implicit, this is the first thing you want to do:
In "Step" module go to "Other" in menu, then "General solution control" --> "Edit" --> choose the analysis step (Step-1). In there, switch to the discontinuous analysis, and increase the number of iterations before cut-back (default is I_a=5), see screenshot attached.
Then, you can use viscous regularization in the material definition.
Or/And you can use automatic stabilization scheme in the Step definition.
Hope this helps.
Hi, Thamaraikannan Seshachalam , did you manage to solve your problem? If you have, please, could you share with us? I am facing the same issue with convergence for damage evolution composite.
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