substructures and submodels 1

[technodam]

can anyone tell me about how to create substructures and submodels in abaqus? it is not much clear from abaqus documentation. it would also be helpful if anyone knows about some video tutorials about this.
also i would like to know how the submodel can be generated using pythion scripting.

 

[burningDiesel]

Well, substructures and submodeling are two different things.
In substructures, you make one 'super element' from a certain part of your mesh, a part that is repeated often (e.g. fan blades on a fan) or part of a larger assembly (e.g. the engine of a car) and you are only changing the bodywork between analysis.
Submodeling is more of a clever way of assigning boundary conditions to a more detailed part of your model. E.g. you load your coarse model and calculate it, and then use this solution as a boundary for a more detailed analysis (either a more refined mesh or more detailed notches, fillets, ... ).

 

[technodam]

Thanks sdebock!!
i know the theory behind the substructures and submodeling. i just wanted to apply that in abaqus to model planetary gear system. i analysed it using normal techniques in abaqus but i want more accurate results and i also hav to reduce the computational time using substructure and submodeling technique.
so let me know the procedure to create substructures and submodels in abaqus. as i mentioned its nt much clear from documentation.

 

[burningDiesel]

Well there is a 2 day Abaqus course on substructering and submodeling, I can't explain it all in forum posts.
You can't be more exact on what your problem is? I suggest you look at the examples manual:

3.2.2 Substructure analysis of a pick-up truck model
1.1.23 Submodel stress analysis of pressure vessel closure hardware
2.2.1 Analysis of a rotating fan using substructures and cyclic symmetry
4.1.10 Substructure analysis of a one-piston engine model

There are probably more.
You should start by finding out whether to use submodeling or substructures.

 

[technodam]

Thank you very much!!
i'll go through these examples.
actually i got the theoraticcal concept of substructure and submodeling very well but facing difficulties applying them in actual model. im analyzing the whole planetary gear system of windmills. it includes planet carrier, gears at various stages and more... the analysis of these components is done in abaqus. so the main aim now is to reduce calculation time either using substructure or submodeling or else any other appropriate technique.
also i would like to know whether python scripting helps in time reduction?

 

[IceBreakerSours]

I have to admit, I don't quite get what specific problem you are facing. It reminds me of students who I used to

acing difficulties applying them in actual model

I assume you mean to say that you are having a hard time *generating* a substructure/submodel?

a) Go to: "Step module: Create Step: Linear perturbation: Substructure generation: n"

"n" is just an ID (a number). If repeated use is expected, a region (i.e., an element set) or the whole model can be designated to be the substructure. There are *many* examples in the documentation for you to go through.

b) Go to: "Load module: Create Boundary Condition: choose Other for the Category and Submodel for the Types for Selected Step: Driving region: Specify"

i want more accurate results and i also hav to reduce the computational time using substructure and submodeling technique

So, you want to use *both* substructuring (for reduced computational cost) and submodeling (for accuracy in, I assume, stress values in a high stress gradient region)?

if anyone knows about some video tutorials

You are in luck! Someone has a posted a short video on submodeling on YouTube.

http://www.eng-tips.com/faqs.cfm?fid=376

http://www.eng-tips.com/faqs.cfm?fid=1083

 

[technodam]

Thank you very much!!
Yes I want to use both sub-structuring and sub-modeling as the normal procedure for analysis takes lot much of time.
I think you are talking about sub-modeling tutorial for 'speed break analysis' on you tube. I went through the video and yes it is useful. Let me mentioned one more thing that I haven't used Abaqus much. I got the procedure for substructure generation as you mentioned, from documentation. also there are examples on substructuring. so i'll go through those and then i'll get an idea how and where to use substructuring and submodeling exactly.
please let me know if there are any scripting techniques to reduce the computational time and to improve accuracy.

 

[IceBreakerSours]

What makes you conclude these are the only options available to you?

http://www.eng-tips.com/faqs.cfm?fid=376

http://www.eng-tips.com/faqs.cfm?fid=1083

 

[technodam]

I know these are not the only options but I couldnt find the other ones also. Also I want to finish this work as early as possible so i decided to go with the options at least i heard of and about which I stuided something.
and yes if there are any other options to reduce calculation time and improving accuracy please let me know those. I will work on them and will use them.

 

[IceBreakerSours]

Can you upload your INP?

http://www.eng-tips.com/faqs.cfm?fid=376

http://www.eng-tips.com/faqs.cfm?fid=1083

 

[technodam]

Sorry but I don't think it's allowed for me to upload anything regarding this project. so if you still suggest some ways for my Analysis problem it would be helpful.
Thank you for your help.

 

[IceBreakerSours]

Can you upload a "similar"/"simpler" INP? If not, then can you give us any indications (upload images?) of what exactly you are trying to do (see example below)? If you can't do any of this, have your boss buy you a few ABAQUS support license tokens.

For example:

"I am running a static analysis using Standard solver. C3D8 and T3D2 elements are used in the analysis. Warning messages in the .dat and .msg files are:

1) Overconstraint checks ..
2) Numerical singularity ..
3) Excessive distortion ..
4) .. ..

The .sta file stops after 5 iterations of the first increment.

Noisy CPRESS at the site of contact is observed."

http://www.eng-tips.com/faqs.cfm?fid=376

http://www.eng-tips.com/faqs.cfm?fid=1083