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I am looking for a way to calculate the overall inner resistance of the electric cable connection with the modeler in my SysML1.4 model.
All necessary values (cable length/material/cross-section area, contact resistances of plugs, etc.) are available within the model. The formula could be modeled as a constraint.
Is there a way to do the calculation within modeler or at least to have a consistent and easy to go workflow (maybe using Excel) that can use the information from the model to do these calculations?
Any help would be highly appreciated.
All the best
The short answer is no, because outside of the VBS scripts for tool automation there isn't a defined expression language for models. This is a major failing for SysML parametric constraint blocks.
Do I understand you right: You see this as a lack in the SysML spec?
Yes you do understand me right. Modeler 8.3 implements, I believe, SysML v1.3. You can download the SysML spec from here: SysML. You'll also need the corresponding UML specification, which can be downloaded from: UML. Even SysML v1.5 does not define an expression language.
You can report issues and make suggestions for OMG specifications at: OMG Bug/Issue Reporting Form - OMG Issue Tracker.
But that does not forbid PTC to use the space that SysML leaves open and offer a solution anyway. Others have done so. (Eventhough it might carry the risk that it might not compatible with a later definition by a future version of SysML. Something that did not bother PTC with other proprietary extensions.)
Having a decent way of filling an Excel-Sheet with all the necessary information (including the formulars) would be fine too. And I can imagine some other paths as well. But I am very surprised that there should be no end-user-doable solution to this request at all. Having to buy Visual Studio and/or do deep extension programming for something like this I find a little too much as an end-user.
Also I am quite surprised that there seems to be no-one, not even PTC themselves, that can share a solution to get the thing done, which workaround o-ever. Is it simply impossible (which I cannot really believe) or does PTC not care to cover such a use-case - that for me would be a real value driver for modeling (and thus a powerful argument to involve more people, which means more sales for PTC in the end...).
I did not give up my hopes yet...
In part, they would say that they already do with the ParaSolver add-on. (I know of it, but have not used it.) In all other respects I completely agree with you. 🙂
I have also (informally) suggested that they should integrate with PTC Mathcad.
One of the issues I have in using SysML constraint blocks (and constraint notes) to express complex equations is the restriction of using simple/plain text without a decent graphical rendering of the expression in proper mathematical notation. (This even leaves us wondering which symbol to use for the multiplication operator, where the use of '*' creates an ambiguity, and for mech-eng consumption I now use 'x' with spaces either side of it.) Mathcad can do it. MathML can do. LaTeX can do it. PTC Integrity Modeler cannot do it!!!
But what's about the Simulink Integration for Integrity? Isn't it possible to run the simulation/computation about this tool?
This is something we are considering for a future release
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