Volume priority in a container 1

[marco1bene]

G'Day!

I am making a cylindrical container, and I've run into a nuisance, since I'm using history based modelling,
NX won't let me make expressions interact between features of different history states.

What I'm trying to achieve is a 1 000 000 mm^3 container, and have it contain the same amount of volume whilst I add features.
So for now, I've been doing it by using expressions, and changing the diameter parameter of my body (and with it the height, so it stays proportional), and I've came within a few 10 mm^3 of 1l, but it's so painstaking, changing the parameter, NX rebuilds the model, analyse it, go back, change it again,… …no fun at all!… :-D

Is there a way to achieve this, or a feature buried somewhere deep inside NX just for that kind of thing?


Cheers, and thank you

Marcel

 

[JohnRBaker]

What version of NX are you running? Have you tried using the Optimization Wizard? If you don't have access to this capability you can also perform an optimization using the 'Goal Seek' function inside the Modeling Spreadsheet.

As an example of how to use the internal Modeling Spreadsheet to perform an 'Optimization', I've attached an OLD (I created this demo part in 1996) demo file that I've used over the years to show people how this function works. The demo solves a very simple problem, not all that different from yours in fact, of "How tall is an 8 oz glass of water?". Of course, the answer is "As tall as it needs to be." but that doesn't really give you anything that you can work with so I developed this demo.

Anyway, open the part file (it was saved in NX 6.0 so hopefully you're using something at least that new) and go to...

Tools -> Spreadsheet...

...and when the spreadsheet opens, select the 'Add-Ins' Excel ribbon tab and then select the 'Goal Seek' option and when the menu comes up, hit OK, and the system will iterate until it gets to exactly 8 oz. You can change any of the Parameter values in the spreadsheet (the purple cells) and repeat the Goal Seek to try a different sizes, keeping in mind that if you do NOT change the desired capacity, changing the 'Height' parameter will not change anything since that is what the Goal Seek if being solved for, the 'Height of the glass'.

To help provide a bit more explanation as to what's going on, I've also provided a 'How to run this demo' readme file which I wrote back in 1996 when I shared this demo with some of my co-workers.

Anyway, take a look at this as perhaps this will help you get what you're looking for, IF you don't have access to the Optimization Wizard, which is of course TODAY'S preferred solution (but the Spreadsheet functionality is still there as an albeit, less modern approach).

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[marco1bene]

John R. Baker!

You've brought a huge smile to my face. Thank you.

As for my software I am running NX 8.0.1… Mac, so I cannot run the goal seek,
because there is no plugin for Excel For Mac, or does it only work with Excel 2004, but I do have the Optimisation Wizard,
how did I miss this one… I actually have another question, when you shell the body, is there a way to use the inner wall of the body
fot the optimisation process?

Thank you for your effort.

 

[JohnRBaker]

Your best best is to extract the interior faces, making sure that they're associative, and using them to create another solid body representing the usable volume of the tank and then use that as your 'volume of interest'.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.