Abaqus/Isight: How to output deformed coordinates and stress information into ODB file

[jl39]

Hi, I am new to both Abaqus and Abaqus Isight.

I have successfully modeled and got simulation result.

I am trying to parameterize my input values and monitor output values from Abaqus by using Abaqus Isight.
I am particularily interested in coordinates of a certain nodes after the deformation and stress information for every node.
I have tried loading my odb file into Isight but it shows only COORD__mag__max, COORD__mag__min, U_mag_max, and U_mag_min for selection option while I want actual (x,y) coordinate of the certain node and stress at every nodes.

1. How do I specify a specific node so that it would output deformed coordinate for that node into ODB file.
2. Wow do I make Abaqus to output stress of all the nodes into ODB file so that I can use it in ODB file.

I would prefer using CAE (gui) but if input file usage is the only option I would happily use input file method.

Thank you.

 

[FEA way]

Abaqus stores deformed coordinates of nodes as output variable called COORD. You can request it in CAE (Volume/Thickness/Coordinates —> COORD). Stress components are saved as S variable. Keep in mind that you can request output variables for whole model or for selected sets.

 

[Mustaine3]

Number 1 is simple:
In Abaqus preprocessing, add a point on your geometry to a set (Tools->Set). Partition the geometry if don't have a point at the location you are interested in. Create a history output request in the step-module, use this set and request COORD. In Isight you can access the history output data.

Number 2 is tricky:
Stresses are element variables, so they are not stored at nodes by default. And you cannot request that as history output (but as field output).
Several workarounds are possible.
a) Create a Python script that exports the needed data from Abaqus/CAE (postprocessing) in a text file and parse those data from the file. This could be done for stresses and COORD, so you wouldn't need the solution for 1).
b) Create a Python script that extracts the needed information directly from the ODB without using the postprocessing routine of A/CAE. Advantage: No CAE license needed when it is done. Disadvantage: you need a special keyword to force the solver to write the stresses at the nodes. This keyword is not supported in A/CAE and could be added in the A/CAE Keyword Editor. This solution also makes answer 1) obsolete, since it could be used for stresses and COORD too.

 

[jl39]

Thank you for your replies.

@ Mustaine3, I think I made a mistake in my wording due to lack of understanding of how Abaqus works.
I am fine with stress values for every element, as long as I can access them in Isigiht.
The problem that I am having right now is that Isight is only showing S_mag_max and S_mag_min for output value option in the Isight, while I want to look at stress values for every element.

Thank you.

 

[Mustaine3]

Isight is doing this, since it makes no sense to have so many result data in Isight. You would have thousands of stresses. What do you want to do with them?
Isight is working with parameters. Do you want to define a parameter for each stress? I guess not.

So what is your goal? What are you trying to achieve? Maybe you are mixing parametric optimization with non-parametric optimization.

 

[jl39]

@ Mustaine3
Thanks for the reply.
I need to optimize my parameters under a constrain saying that stress states have to be tensile (positive).
Therefore, I want to look at stress values to check if they are positive. Specifically, I want to see S11, S22, and S33 values.
In the course of doing my project, I found out that I don't need to look at all the stress values, but only at some selected location.
I have tried doing so by generating a set of elements and a field output for stress values of the set, but Isight does not show stress values that I want but only shows S_mises_max and min values for the whole model.

 

[Mustaine3]

You are aware, that S11 etc. are not telling you if there is tension/compression?

With a limited number of values you can use the options If described in my first answer.