FEA on bolted assemblies???

[TomUSPSEngrg]

Will the next release of Inventor have the capability to perform FEA on bolted assemblies??

T

[PeteMaxfield]

Greetings Tom,

We can not comment on the timing of future funtionality in this forum, however I can say we are looking into pre-stress bolts, as well as idealized bolt connection patterns, so bolts are not meshed but instead represented by ideal contacts.

Kind regards,
Pete
Product Design Lead

[dloganbill]

Have these features been implemented yet?  We are attempting to analyze a large steel structure with bolted connections.

What is the proper work flow for analyzing bolted conections in a large structure?

[davef]

Any news on this topic?  I'm also looking to perform an FEA on a bolted assembly and notes on best practices & workflow will be greatly appreciated.  Thanks.

Dave

[mcgyvr]

Just a warning/information.. (and I have no knowledge of your knowledge on the subject but)

Proper/accurate FEA is not something for the untrained. There are engineers that specialize in that field and have studied/trained for it and is NOT something anyone can do "properly".

FEA analysis requires a professional understanding of the concepts/appropriate constraints/meshing,etc...

Way more than what a few online tutorials can provide IMO..

Personally I would never try to "internet train" someone to perform FEA analysis.

But a google search for Inventor FEA should get you plenty of simple online basic tutorials to start your learning process.

[davef]

Took courses in FEA in college - but 25 years have passed since then.  So, knowledge is rusty/light; but understanding of concepts and ability to learn quickly is in good shape.  Thank you for your concern.

I've worked for and alongside engineers in their late 50s that achieved "guru" statuses in various computer tools well after they completed their formal university educations.  I wonder how often they were warned about venturing into areas that they had not yet mastered.  I trust you are not advocating that we all graduate from formal educations and count the days until we die or retire without reaching out (via online forums, face to face interactions, books, etc.) to learn new skills or to advance existing ones.

Your point (concern/warning), and clumsy delivery, have been noted.

To those that are interested in helping one advance his knowledge of the subject (best practices/ workflow or maybe just tips for FEAs of bolted assemblies), your help will be truly appreciated.   

For information/reference: I am interested in the stresses in an unstayed pressure vessel head and in the vessel's mating flange.  (These things are kept together with pre-stressed bolts.)  The geometry of the head is [necessarily] complicated.  This complicates application of the applicable ASME rules, so an FEA is desired as a confirming check.  The flange geometery also [necessarily] deviates a bit from ASME B&PV code details, so we'd like to check it as well.  

[mcgyvr]

No offsense was meant.. I just see too many people who think they can do FEA "properly" just because it comes with Inventor. And companies who think that their cad monkeys can do it too and it just scares me when safety is concerned. 

[blair]

You may wish to upgrade to Simulation Mechanical 2014, it has the ability to deal with bolts/fastners.

http://wikihelp.autodesk.com/Simulation_Mechanical/enu/2014/Help/0328-User_s_G328/0479-Mesh_Mod479/0...

This is somewhat beyond the FEA package that is packaged inside of Inventor.

[davef]

Hello Blair.  Thank you for the feedback and link.  Yes, it does appear that we need the full blown analysis package.

I feared we'd run into a situation requiring the full blown package.  I was hoping that more than a month would pass, though, after buying the Product Design Suite before the situation came up.  Oh well.

Thanks again.

Dave

[blair]

You can do some work-around by using the Split-Face command to create "Load-Spots" on the face of the object to replicate the load forces applied by the fastener and applying "axial/vector constraints" on the inside face of the bolt hole.

It is a work-around, you will most likely have to do some digging for information to get the correct load/clamping force for your fasteners at the desired torque.

[Xun.Zhang]

Hi Tom,

Although we don't have a devoted bolted connection feature / load or contact type, there are ways you can get close.

The most straightforward would be to split the faces of the flange or plate with the "footprint" of either the washer or bolt head.  Exclude the bolted connection from the Simulation.  Then create a manual contact using those split faces.  You can use Bonded or spring type contact.

This gets more tricky, but you could also cut a section out of the bolt shaft itself, so there is a gap.  Then, create a pre-tension in the bolt by adding a force to each half of the bolt (on the newly created faces by the cut) pointing towards each other.  Be sure to make the cut wide enough so that it lies outside the default distance for automatic contacts or else a bonded contact would be made, and the forces wouldn't have any effect.

If the bolts were placed from Content Center, you cannot modify them with the cut, unless you chose to place them "As Custom".

Hope it helps!