I am modeling drained triaxial compression test. I modeled soil as cylindrical part in abaqus. Bottom part of cylinder is fixed and on top displacement is applied. I used Dynamic/explicit steps. After running model and getting .odb file, couldn't match stress strain diagram from experimental results. I don't know whether i am calculating stress in right way or not. Can anybody guide me in this regard? Advanced thanks for your reply.
S1-s3 is the stress invariant called Tresca. For the point of interest, create New xy data from field data for Tresca and axial strain, then create New xy data by operating on xy data and use the operator "combine" to make the stress vs strain data for plotting.
In this model, total number of nodes: 1095
Total number of elements: 840
840 linear hexahedral elements of type C3D8R. We can plot stress vs strain for any of element or node.
How i can plot (S1-S3) vs axial strain for whole model?
I don't understand the question. The stress and strain are field quantities and the values will change over the volume. You have to evaluate them at a single point. Otherwise you could plot load versus displacement for the whole model and compare theses to tests, in which case you follow a similar method to my previous answer for generating XY data by operating on existing XY data.
Ok thanks for your reply Sir,
Actually when i am summing up reaction force at bottom which is fixed b.c and dividing it by c/s area of specimen, i get stress. But c/s area will be changed also. How i can find actual area for each increment of displacement ? It is strain controlled test. For axial strain, i extracted U3 and dividing it by height of specimen. Is it correct way? Again i am getting difficulty to find volumetric strain. I took LE11, LE22 and LE33 and made average for whole model. Then i summed up (LE11+LE22+LE33) for volumetric strain. I am not sure for that.
Any guidelines will be encouraged.
I have tried (S11-S33) vs axial strain but couldn't get plot similar to experimental plot.
Maybe you can use the "create field output" option to create your variable as explained here
http://www.egr.msu.edu/software/abaqus/Documentation/docs/v6.7/books/usi/default.htm?startat=pt05ch24s05.html
Then, once you have your new field output (in your case s11-s33) you can plot it vs axial strain by using the "xy plot" option. This can be made for the whole model but if you have 3D geom it will be very difficult to understand the relation between the plotted results and the real node.
Hope it helps.
Franco
Ok.Thank you Franco Concli..I am trying to get the plot. Can you give any idea of plotting Volumetric strain vs axial strain?
Its been long since you have asked this question in the forum. I am not sure whether you have resolved the issue. I will try to share my thoughts.
Sorry for delay in answering. I was away from work due to holiday.
Thank you Nithin Sudersanan. I ran the model, it was working nicely for Triaxial compression test but i couldn't validate it for Triaxial extension test.
Can you help me for Triaxial extension test modeling using Drucker-Prager constitutive modeling.
Digvijay sir ,
I am working on cylindrical triaxial modelling of railway ballast. I am searching for drucker-prager hardening parameter yield stress and absolute plastic strain. can you plz give me some idea, how you took yield stress and plastic in your model? Bcz I am dealing with same problem. Plz reply
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