Dynamic simulation, ball joints.

[richardWE24B]

Hi All,

New to Inventor and especially to assemblies and dynamic simulation.  I am trying to build a simple 'twist to steer' mechanism and I cannot get the ball joints to work to complete the assembly.  The last one always causes a conflict.    Initially I had the spherical joints as sub assemblies with the ball joint and tried placing them with conventional axis/axis constraints but the ball joint didn't work in the larger assembly.  I have separated the balls into the higher level assembly and this seems to do what I want except for the last joint.  Any pointers on where I am going wrong would be appreciated.

Richard.

[johnsonshiue]

Hi! Please attach all the files including ipt and iam files. The top-level assembly file does not contain all the geometry.

Many thanks!

[richardWE24B]

Dear Johnson, 

Please find attached .rar folder with the parts and sub assemblies for the rear steer mechanism.

Appreciate you looking at it.

Best regards,

Richard.

[johnsonshiue]

Hi! There are a few files missing. Please attached the following files.

Spherical Bearing.iam

Symmetry of RC-BM-RST-0917-C001.ipt

COM-M6-AuroraBearingCo.-09-22-2017 (1).ipt

Many thanks!

[richardWE24B]

Hi Johnson,

I am really demonstrating my lack of Inventor skills.  I thought I had deleted these parts. 

I got the bearing from the Aurora website, I then made a sub assembly from that by defining the ball joint in that sub assembly.  I couldn't then build the assembly and have the degrees of freedom carry over in the higher level.  I deleted the ball from the spherical sub assembly to put it in the higher level assembly to make the joint with the degrees of freedom at the higher level.  This gave me what I was looking for up to the last connection which is where I ran out of ideas.  The 'upright' and it's symmetry part are renamed Upright LH and RH.  The missing parts are in the zip folder attached for completeness I've added the wheel and part ....c005 this is intended to be a composite leaf spring that locates in the slots in the uprights.

Sorry to make things complicated!

Many thanks,

Richard.

PS Just for info I've added a picture to put the assembly in it's context;  Lean to steer!

[JDMather]

Did you resolve this issue?

You are more likely to get wider range of user input by using native Windows zip utility rather than using 3rd party rar compression.

Personally, I would never install a (free) rar extractor on my clean Inventor machine.

[richardWE24B]

Not as yet.

Richard.

[dgorsman]

@JDMather - RAR is popular with software developers, especially with the open-source dev crowd.  I'd consider it as safe as ZIP/WinZIP, but otherwise agree the latter is the better choice for general use.

[johnsonshiue]

Hi Richard,

Part2.ipt and Part3.ipt are still missing. Did you use Pack&Go to include all the files? We are trying to help but we do need a complete dataset to understand the issue better. We are all here learning and helping each other regardless of the skill levels. Inventor is a powerful tool but sometimes it is a bit hard to understand.

Many thanks!

[richardWE24B]

Hi Johnson,

Apologies once again!  I'm a long time CATIA user and this old dog is resisting learning the new tricks! I have now learnt 'pack and go' so that's something I guess. 

Attached a new zip file with the pack and go folder of the assembly.  I hope this works.

The time spent and feed back is certainly very appreciated.

regards,

Richard.

[JDMather]

I like to give problems like this to my students to solve.

I insist that they fully define all of their sketches before moving to an advanced topic like Dynamic Simulation - so the first thing we will have to do is go through each and every part and examine the Design Intent.

[JDMather]

This is an interesting problem, but without parametric history it would take me an estimated 3-4 hrs to solve and then I would need to create the geometry from scratch (to satisfy myself).  You have something off ever so slightly.

Eventually I will solve this one as it is interesting to me.

When I model something like this - I start out with simple stick figure lines.  The mechanism can be laid out and tested in a skeleton part file  with Sketch Blocks of simple 2D sketches before ever modeling any solid geometry.

I would then use multi-body solids technique, and finally, push out the assembly.

[JDMather]

So far I have discovered 2 critical errors - I was able to fix one of them, but still working on second error.

(There were at least 2 minor errors as well.)

[richardWE24B]

Hi JD,

I certainly appreciate the feedback.  I didn't realise the can of worms I was opening!  I expected a simple, 'change this constraint, or do this first then this..' kind of reply. 

I'm not surprised there are Inventor modelling errors.  I'm a long time CATIA user and probably trying to force Inventor into my methods rather more than I should.  There are a lot of attractions to Inventor with the included functionality over CATIA where the 'CAD+' functions like this dynamic simulation are expensive add ons.  I working on parts modelled in CATIA, hoping they could be assembled in Inventor to use in these environments, if it's sensitive to the modelling history of the part that seems then it might not be so simple.

Regards,

Richard

[JDMather]

Well, it was only sensitive to history in the terms that without the history it took much more effort to track down the issues. I hope to have a working assembly soon.