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Cyclic Dependency Error

hi.. please go throught the image attached, and let me know if there is a solution to this problem. I'm using this setting for a suspenstion conditions, but its not workin the way I think the CAD will work. is it some sort of bug in SE? I'm using ST3 .. Thanks in advance for your time.. 

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Re: Cyclic Dependency Error

I forgot to mention the lower ball shown in the image will move (depending on normal ride/ full bump/ full drop) say +/- 80mm roughly. But the distanance A and B should retain as it is and the constrains shouldn't fail.. I hope the requirement is clear. please let me know for any clarifications. 

Re: Cyclic Dependency Error

Hi Matthew,

 

You might find this info from the "Knowledge Base" very helpful to your design....http://community.plm.automation.siemens.com/t5/Solid-Edge-Knowledge-Base/Conceptual-Mechanisms-Hands...

Sean Cresswell
Design Manager Streetscape Limited
Solid Edge ST10 [MP0] Classic [x2 seats]
Windows 10

Re: Cyclic Dependency Error

[ Edited ]

Not sure about the circular dependancy issue. Depends on the relationship system you have setup.

 

For cases like this I usually use an ASM sketch and a PATH relationship to limit motion.

Also, I also use constructions to define positions of parts. Cylinders added to Blue and Grey parts in this case. The lengths of these can be edited to set the A and B lengths.

 

In the video below the yellow part is just coming along for the ride.

 

http://youtu.be/ddj_Es2rX0k 

(Hope the link works)

 

The system is constrained to move in the XZ plane. If you need it to tilt additional constructions are required.

 

Can't send you the files as I am on ST7.

 

Hope this helps.

 

Thanks,

 

Art

Solution
Solution
Accepted by topic author matthew
‎08-26-2015 04:32 AM

Re: Cyclic Dependency Error

Hi Matthew,

 

In a case like this, I found that the connect relationships in particular are a poor substitute for actual drawn components (even just temporary ones) representing those lengths, and the relationships take much longer to set up and manage without them. 

 

(Experience: having just done the exact same thing with a suspension design side project..)

-Dylan Gondyke

Re: Cyclic Dependency Error

Hi Everyone.. Many thanks for all the suggestions, its very interesting to know the sketch has so much of potential in the assembly..  Will apply it in my design and see the results (Sean, thanks for the instruction PDF)..

 

Dylan,  As suggested, instead of the ball joint, I will draw these parts and check (So now, instead of 4balls joints, there will be 2 parts, each parts contains 2 ball joints connected with a rod?). I will still need to use the connect relationship to make sure these tilt in any direction as needed. I think since the constrains reduces now I will not get the error, will try this tomorrow..  Thanks for your advice..

 

Art, Thanks for the video, thats much inline with my thoughts. I just want to make sure of the following points. The path sketch 160 shown in the video, I hope this can be changed while using an alternate assembly? I forgot to mention about the roll condition, where the vehicle 'rolls' sideways say 5deg +/- .. The path sketch 160 will cater to 3 positions, and for roll, I can have another path? Currently I have 3+2 alternate assembly in the main assembly. 

 

Thanks,

Matthew. 

Re: Cyclic Dependency Error

hi Dylan,

This has worked perfectly.. Smiley Happy Thanks.

Regards,
Matthew

Re: Cyclic Dependency Error

[ Edited ]

Glad it helped! Here's a little picture of some of what I just did...the ball joints and heim joints are all adjustable subassemblies with all ball/cup relationships free. Early on, I had a lot of dummy components that just captured the endpoints I was mocking up in any way possible. This eliminates the number of constraints you have to manage and makes it simpler to swap out pieces. It also makes dragging the components up and down much quicker, since there is less to compute. 

-Dylan Gondyke

Re: Cyclic Dependency Error

Sorry for the slow reply.

Rather than use an ASM Sketch the sketch can be placed inside another part file so it can move/tilt as well. You can add a sketch in the ASM to control the tilt of this part. (or another part that is grounded)

 

Actually I would use a Sync construction part so I can easily edit it from ASM to adjust lengths etc.
I've kind of gotten into the practice of using sync solids this way rather than sketches.

 

You can use Alternate Position ASMs but swiching these out is not as smooth. I would use adjustable ASMs and variables/relationships to lock things in position as pointed out in another thread.

 

I took some time to model this and animate it in Keyshot using ST7. See attached video.

Keyshot is way cool

 

http://youtu.be/rJ8PTQlAY6A

 

Glad you were able to work this out.

 

Thanks,

 

Art

Re: Cyclic Dependency Error

Hi Art, thanks for the super cool video.. Smiley Happy I will surely have to learn keyshot to improve the presentation side of the job.. Also I’m yet to work on Sync.. As you suggested, I think by drawing the sketch inside a part will also solve the problem, will try this method as well.

 

I think if we don’t use alternate assembly, we cannot save a position and each time we need to manually go and change the constrains/ variables. It is easy for the person who modelled it but will be difficult to explain to someone who sits in a different location (whereas in alternate assembly, I can mention which member to open). I’m not sure if we can ‘save some variables sets’ like the display configuration, in a normal assembly.

 

Thanks,
Matthew