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change dimension to keep volume

omarhernandez

New member
Hey everbody,


I am trying to set up a multi-objective design study. I at least know the name of the function I am trying to use but don't know if that is the correct one!


Let's us say that I need to make pro/e udpate a length of a rod to keep the same volume (input but constant) when I change the diameter (also input). Am I using the correct function (Multi-objective study). I will later add more dim, but am using this ex as asimple case. The person usually incharge of this is gone, and i am stuck will all of his work for the time being!!



I keep getting a error message when trying to select the goals "There are no available parameters. Only top-level analysis features' parameters are allowed for selection here." - can someone explain


Thanks
Edited by: omarhernandez
 

Kaz Z06

New member
It sounds like what you want to do is perform a "feasbility study" - you wish to find out if it is possible to achieve a given volume by changing the length. If this is what you're looking for, use "feasability study". The "MODS" (Multi-Objective Design Study)is to conduct DOEs - very powerful itself, but will not address what it sounds like you are trying to accomplish.


It also might sound like you wish to use a simple relation in your model to maintain a specific volume no matter what you do to the other dimensions.


Cheers,


Kaz
 

omarhernandez

New member
Thanks for the help Kaz!


Well at least I know what proper analysis to use now. "feasibility study" menu manager looks a lot like the "MDOS" one. I can't seem to get into the "Design Constraints" selection window (just like in "MDOS")


Pro/E keep prompting me "There are no availible top-level features' parameters" I tried looking in the help, but no luck. What exactly are these feature parameters? How do I create one? I wanted to use the following constraint - MP_VOLUME("") = value. Has anyone ever done somthing of this sort. Any suggestions would really help.


Thanks,


Omar
 

marschalek

New member
For the example you mentioned, Kaz Z06 is correct, you
should be using the Feasibility function under Analysis
> Feasibility/Optimization.

For your second question, you need to create a datum
analysis feature that creates the volume as a parameter.

Analysis > Model > Mass Properties, change the type from
Quick to Feature, and complete. Now you have the
"volume" parameter that you can use in any analysis.
 

omarhernandez

New member
Wow that's is great! I'm not so crazy about how I must compute the analysis in order to get the dimension to update, but rather use this method than do it manually!!!


Thanks Jim you saved me from many headaches (calling tech support)
 

omarhernandez

New member
quick question--- How does pro/e determine hot to change the design dimensions when trying to maintain a user specified volume. Theo, If you have two dimension there can be a number of solutions. How does pro/e pick the one it picks
!


Funny way of saying it!
 

marschalek

New member
If changing both dimensions will move closer to the constraint, Pro/E changes both by the same percentage. If one dimension hits a limit, then the other dimension(s) take up the slack.
 

Kaz Z06

New member
Omar,


Afeasability study is the same analysis as an optimization with the exception that there is no "goal" to achieve - like minimizing or maximizing a measure. This means that any dimension you choose to have Pro/E vary will change in any way/combination in order to try to meet the contraint(s) you have set. There may be an infinite number of ways to meet the constraint(s) through different combinations of the dimensions you choose to vary. Only when you ask it to become an optimization will BMX try to select the proper combination of your dimensions to minimize/maximize the additional chosen goal.
 

omarhernandez

New member
Very good expenation guys! Thanks for the great help. You got me out of a jam! I will be taking the behavior modeling course in the next month! Thanks again Kaz Zo6 and Jim!
 

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