homogeneous stress for a tensile test
homogeneous stress for a tensile test
(OP)
Hello everyone,
In these last days I try to study the stress in a simple tensile test, the main goal of the exercise is to display at the end an homogeneous stress along the part. To do so, I have begun to completly constraint one side of the part (Tx=Ty=Tz=0) but the results don't suit me as if any transverse displacement were locked, thus I have decided to lock the structure in one direction (longitudinal direction) but when I read the reuslt file f06 it is written:
USER FATAL MESSAGE 9050 (SUBDMAP SEKRRS)
RUN TERMINATED DUE TO EXCESSIVE PIVOT RATIOS IN MATRIX KLL.
USER ACTION: CONSTRAIN MECHANISMS WITH SPCI OR SUPORTI ENTRIES OR SPECIFY PARAM,BAILOUT,-1 TO CONTINUE THE RUN WITH MECHANISMS.
I don t know what to do.
thanks a lot.
In these last days I try to study the stress in a simple tensile test, the main goal of the exercise is to display at the end an homogeneous stress along the part. To do so, I have begun to completly constraint one side of the part (Tx=Ty=Tz=0) but the results don't suit me as if any transverse displacement were locked, thus I have decided to lock the structure in one direction (longitudinal direction) but when I read the reuslt file f06 it is written:
USER FATAL MESSAGE 9050 (SUBDMAP SEKRRS)
RUN TERMINATED DUE TO EXCESSIVE PIVOT RATIOS IN MATRIX KLL.
USER ACTION: CONSTRAIN MECHANISMS WITH SPCI OR SUPORTI ENTRIES OR SPECIFY PARAM,BAILOUT,-1 TO CONTINUE THE RUN WITH MECHANISMS.
I don t know what to do.
thanks a lot.
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RE: homogeneous stress for a tensile test
RE: homogeneous stress for a tensile test
interesting, then it means that i need anyway to fix completely one side, but i don't get the point when you say that i can use the symmetry of my model.
what are you refering to ?
thanks for your answer
RE: homogeneous stress for a tensile test
RE: homogeneous stress for a tensile test
RE: homogeneous stress for a tensile test
Thanks
RE: homogeneous stress for a tensile test
- Make sure you have a relatively fine mesh if you want to look at stresses. Based on your dimensions, you may want to use an element edge length of 2 mm or even 1 mm.
- By default, Patran will plot averaged results for fringe plots (which will miss absolute peak stresses). You can't turn averaging off from a "Create->Quickplot" you need to use "Create->Fringe" in the Results Form in Patran. I believe the actual setting is something like, "Domain: None" in one of the fringe plot settings.
- When you removed the Tx constraint from one end of the mesh, the model was free to move in the Y-direction which resulted in the negative pivot ratio error in the f06 output file. This is because you can't have rigid body motion of your model in a linear statics solution. You need to constrain at least one node in the model from y-displacement.
Question: When you successfully ran your model with the full constraints on one end, what didn't you like about the results? If I was going to simulate a tension test, I would constrain all degrees of freedom at one end and pull on the other end.