Behavioral Modeling Extension

[Mloew]

I believe that the Behavioral Modeling Extension functionality for Pro/E is one of the best features of that software and certainly one of the most misunderstood. Here is some information I have compiled to make better use of the BMX functionality.


The syntax for relating the analysis features is as follows:


parameter_name:FID_analysis_feature_name


Thus, if you were using the "length" parameter from a analysis feature "Analysis1"; it would be:


length:FID_Analysis1


A listing of the functions used in relations can be found at thePTC Technical Support Knowledge Base. Note: you must have maintenance to search the knowledge base.


Here are some links to free information from PTC available on the web:
Pro/ENGINEER Behavioral Modeling
PTC Tips and Tricks: Solving Engineering Problems with BMX
Using a User-defined Analysis and Behavioral Modeling Extension to Maximize Projected Areas (video)
Pro/ENGINEER Wildfire 2.0: What's New -- User-defined Input for Multi-objective Design Studies


And these from the PTC Customer Care Zone:
BMX Tutorial (downloads a .zip file)
Customer Care E-Newsletter: Pro/ENGINEER Behavioral Modeling Extension (BMX) & Solving Engineering Problems w/ BMX


Links to articles:
Profiles Magazine:
Put an End to Endless Iterations with Behavioral Modeling
by Dana Coombs, SYNTHES Maxillofacial
Using Pro/ENGINEER's Analysis Feature Effectively
By Asim Rashid, Wahid Industries Limited
Desktop Engineering Magazine:
Building a Better Bicycle
By Louise Elliott

Please let me know if you find any other information that I should add to this list.


Best regards,


Matthew Ian Loew

 

[Israr]

The only book on the subject (BMX) , for release Wildfire, is available from CADQUEST.





Israr

 

[jridge]

PTC Offers a short course in BMX, but its really easy enough to learn on your own with a little bit of initiative. The basics of BMX are nothing more than the standard optimization tools that any analysis package uses; sensitivity, feasibility and optimization. The power of BMX lies in the ability to incorporate a new type of feature into a solid model, who's only purpose is to calculate and store the results of an analysis.


Lots of design problems can be solved quickly by identifying a goal, providing a range for the sensitive variables and letting the optimization find the solution. For example... say you have a tiny edge created by the near intersection of two features. You know that with just a little more length to one variable the edge would become a common vertex. I use a feasibility study, measure the distance between the vertices, set that distance to (0) as a design constraintand pick the adjustable feature dimension forcing it to the design constraint and poof...

no more short edge.


That's just one of about 20 daily uses I have for BMX. BTW, CADQuest has excellent books.


Best regards,


JC Ridge

 

[Mloew]

Jim,


Thanks for the simple example! I think it helps to better understand the functionality in BMX.


Best regards,


Matthew

 

[Israr]

Sir Mathew,


I have a problem of BMX/ The problem is quite interesting. I am attaching the jpg file of it.View attachment 725


I want the ladder to lift from zero to 90 degree, minimize jack length and ternary and binary links, and simultaneously achieve the goal of minimum force required and the assembly have no interference.


If you are interested I can send the assembly.


Israr

 

[Israr]

Sir Mathew,


Just to inform you that I am using WF 2.0


Israr

 

[Mloew]

Israr,


Isn't everyone?

I sent you a private message with my email. I am very in terested in your example. Thanks!

 

[Israr]

Sir Mathew,


Actually the file size is about 3 Mb so can't be uploaded here. BTW the old procentral had no limit to attachments.


Israr

 

[pedja666]

In WF2.0 a Mechanica analysis has been added to BMX.<?:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" />


So we can imagine following scenario:


-Engineering department with say 8 designers and an engineer familiar with FEA and Pro/M.


-Designer A has to design a supporting beam which spam will depend on design requirements and limitations. The cross section will be designed according to the strength requirements (Max VM Stress with safety factor of 1.5)


- Beam spam will change et least few times during design cycle due to different design iterations.


The best and most efficient solution solution is:


1- Designer creates initial beam geometry an hand it down to the engineer


2- The Engineer set up the model and do the analysis


3- Designer takes the model back and perform the mechanica analysis extracting the max VM Stress as parameter (No Mechanica knowledge is necessary for this)


4- Designer creates a optimization study setting the max VM stress to be Yield Stress/Safety factor and the cross section dimensions to be variables


5-Designer creates a optimization feature from this study.


Now he can change the beam spam as many times as he wants ProE and ProM will adjust the cross section geometry automatically.No need for the engineer to do new analysis after each eteration


The requirement is at least one floating license of ProM in the department

 

[Israr]

Pedja,


Thanks for the guidelines. If you need I can send you the assembly. You always accept challenges. So let you have another one.


Israr
Edited by: Israr

 

[pedja666]

Israr<?:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" />


One thing that I failed to mention is that this kind of optimization particularly when Mechanica is involved take a significant time to complete. Even this simple example that I stated above and your example is much more complex.


Sorry but right now I do not have the time for this. Your example is a typical example for use of BMX and optimization because your design requirement are in conflict with each other and you will have to find some kind of compromise.


The shorter your links are the more difficult will be to bring the ladder up meaning more stress for your links. If your ladder are brought up by a electromotor you would have the first constraint regarding max allowable torque. After that I would design the initial geometry fulfilling 0-90 degree requirement. Than go to Pro/M and analyze the links. In the end do mechanica and optimization study in BMX setting the the length of the links as variables with the min length you already calculated and max length by your judgment and vm stress in the links as the goal.


And prepare yourself for the long run

 

[Israr]

Pedja,


By now I want only lengths and angles optimizations and I want to take for granted the cross-sections and material. But I want the force applied by the hydraulic jack to be minimized. I want the mechanism to be powered by hydralulic jack as shown in the picture.


So would like the help in this connection.


Israr

 

[pedja666]

Well israr<?:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" />


That simplifies the problem a lot.


-First do not use the real assy for optimization. Create a skeleton or a part with curves representing your geometry only.


-Do optimization for the worst case which is when the ladder is in 0 position


-If "a" is the angle between the ladder in zero position and hydraulic jack your basic equation is F*SINa*B=G*L/2 where


G is the weight of the ladder


F is needed hydraulic force


B-distance between the ladder pivot point and the point of connection between the ladder and jack


L -Length of the ladder


So you see that your hydraulic force depends on two variables


1- angle a


2-distance B


The greater both of them the lesser is the force and the longer the jacks.


So set the angle

 

[Israr]

Pedja,


Thank you very much for reply. I have already done this. Actually the problem is of interference, and the achievement of both 0 and 90 degrees simultaneously.


When I get values from optimization and set those values either the assembly gets global interference of it does not achieve 90 degree.


If you say, I will send you my assembly along with optimization results.


Israr

 

[puppet]

out of interest where did that equation come from?

 

[pedja666]

The equation comes from a simple summation of moments around the ladder pivot when the ladder is in zero degree position (the position that requires the greatest hydraulic force).<?:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" />


Israr


The interference, you have to deal with particular geometry and probably thathave tobe done manually. As for inability to reach 90 degree position after optimization maybeyou should change the scenario by setting the length of the jack as the variable with min and max value previously calculated and necessary to reach 90 degreeanddo optimization by maximizing the other two values: angle and distance.If your file is too big for upload suppress all features and than upload it.I did it once here and it worked