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# creating stress response with flexibel element range

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hello

i would like to create an optimization approach in hyperstudy. i use a tcl-script based model file with parametrized geometry to generate my .fem model. the objective is to minimize the geometry till a certain stress level is reached. i define my stress response with the "max(resvector(...))" function.

this works well, but due to the changing geometry in the optimization approach, the script use a criteria-based automesh function to obtain a good element quality. as a result, the total number of elements varies and i get a error message "index out of range" for "resvector" if the number of elements are below the end_request arguement of the function. so i want to implement some kind of automated element range function (minimum to maximum element index) into the "resvector" function.

question: is it possible to include a dynamic range of elements into the "resvector" function?

[f.e. "resvector(file_name, type, 0 [start_request], maximum element index [end_request], ...)"]

greetings

stefan

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Hi Stefan

If you can create responses that gets the minimum element index and maximum element index, you can use these responses in your resvector definition such as

max(resvector(getenv("HST_APPROACH_RUN_PATH") + "/m_1/beam.h3d",1,0,r_6,0,0,0,1))

In this example, minimum element index is always 0 but maximum element index is another response (r_6). This response, r_6, in this case, reads the number of elements from the OptiStruct output file.

Hope this helps

Fatma

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Hello Stefan,

To add to the above reply from Fatma: you could define something like r_6 using a HyperMath function like:

function getNumReqs(fileName,type_index,subcase)
s = GetSubcase(fileName,subcase+1)
numReqs=s::GetNumReqs(type_index+1)
return numReqs
end

This function can be registered for use in HyperStudy making it accesible just like any other function.  So for example after registering it, you would define r_6  to have the expression :

getNumReqs(getenv("HST_APPROACH_RUN_PATH") + "/m_1/beam.h3d",1,0) where 1 and 0 are the Type and Subcase referenced by resvector.

Thanks

Joe

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Hello Fatma and Joe

Thanks a lot for your help. My solution: As Fatma has been suggested, I create a new response (element_max) to get the maximum element index. For that purpose, I use the "ASCII Extracts" function in the expression builder, with the .out as file source (where I can find the total number of elements) and use the keyword "Elements                  :    " to define my response.

It´s then "max(resvector(getenv("HST_APPROACH_RUN_PATH")+"FILENAME",1,0, element_max-1,0,0,0,0))". -1 because the index starts with 0!

It´s not as pretty as Joe's hint, but it works fine for me.

Stefan

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