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Example of a Pressure Tank Modeled Top-Down, where Equations Driven Parts update as the assembly is copied with new file names

Question asked by Mauricio Martinez-Saez on Nov 20, 2009
Latest reply on Nov 23, 2009 by Alessandro Frattini

Recently I see many posts here related to Top-Down parametric modeling, Design Tables, etc.


Attached is a very simple example of a cylindrical pressure tank modeled Top-Down and 100% parametric, the example show how:


1.- Model the assembly Top-Down using a Referential Geometry Part placed at the top level, which can be copied as required to sub-assemblies of larger model, to be use to relate parts to the geometry.  Changes made to instances of this part at any level will propagate across the entire model.


2.- The "Flange" part have two equations driving the thickness of the flange and the number of holes,  this equation will update correctly when the model is copied to another folder to generate a new project and names of the part files are changed during the "copy" process (do not change the name of the "Ref-Geometry" part).  The equations are not necessary to model this part (since it can be related by geometry) but I created them to show that when the model is structured this way the equations do not get loss when the model is copied to a new folder with new file names.


Since the origin of relations and values for the equations are inside the "Ref-Geometry" part, the relations and values (input variable names for the equations) will always be correct.


To change the tank to another size, open the "Ref-Geometry" part on his how window (in-context, or alone) and open for editing the design table on this part, this will show a simple "configurator" where you can change the values driving the internal volume of the tank and some dimensional parameters, them close the table, save the "Ref-Geometry" part and close it,  if you open the part in-context of the assembly, the assembly will rebuild to the new configuration.  If you open the part alone, then once it is saved and close, open the assembly and it will open to a new configuration.


To copy the model to a new proyect, use the Copy Files function inside the File > Find References window,  then select a new folder and change the name of the parts as you may like (except the name for the "Ref_Geometry" part.


This show the basic principle for doing a top-down model, the example is done very simple in order to allow to be analyze easier.  This same method can be used to produce very complex assemblies having multiple subassembly levels and large number of components.  As time allow I will create more complex models and post them here.


The DT inside the "Ref_Geometry" part is protected but it can be unprotected by opening it on Excel since it do not have any password code.  To se the complete table, you will need to Unhide the rows and columns that are hidden on the Excel sheet (I believe you know how to do that).


Hope this will be of help to people wanting to utilize to-down modeling.


Tank Assembly Example.JPG