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Dynamic Simulation: How to apply an acceleration?

17 REPLIES 17
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Message 1 of 18
FabianNie
2255 Views, 17 Replies

Dynamic Simulation: How to apply an acceleration?

Hi forum,

I know how to apply a force in a dynamic simultion. But how do I apply an acceleration?

 

Thanks for you help,

Fabian

17 REPLIES 17
Message 2 of 18
JDMather
in reply to: FabianNie

Have you gone through this book?

http://vrblog.info/

Attach your assembly here.

 


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Message 3 of 18
FabianNie
in reply to: JDMather

Thank you for the answer.

I had a quick look on this website but it doesn't seem to deal with accelerations.

The version I run is Inventor 11, in case this is important

I designed an acceleration sensor carrier and now I would like to see how it deforms if an acceleration is applied. Like putting the carrier on a sled and accelerating the sled. Hope you don't need the assembly to help me.

 

Fabian

 

Message 4 of 18
JDMather
in reply to: FabianNie


@FabianNie wrote:

 

I had a quick look on this website but it doesn't seem to deal with accelerations.

 


I have the book right in front of me and there are examples of acceleration

http://www.amazon.com/Running-Autodesk-Inventor-Simulation-Second/dp/0123821029/ref=sr_1_3?ie=UTF8&s...

 

 

Did you open the attachment image in my previous post?

 

Your job might be as simple as adding a Body Load in FEA environment - in which case you don't even need dynamic simulation. (see attached)

 


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Message 5 of 18
swalton
in reply to: FabianNie

I believe that dynamic simulation is rigid body motion only. 

 

If you want to see deformation, you should use the FEA package. 

 

Create a gravity load and mulitply the stock mangnitude by the #of Gs you want to simulate.

Steve Walton
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Message 6 of 18
FabianNie
in reply to: swalton

JDMather: Sorry, I didn't see the first attached picture. But I did see the second one at once.

 

I quickly drew a part and apply an acceleration. The result is attached. I'm a little confused about the direction. The arrow is pointing from the left to the right. I think the part should bend to the other direction. Is there a way I can do this simulation with an assembly? Or is it like swaltan says a rigid body simulation?

 

Fabian

Message 7 of 18
JDMather
in reply to: FabianNie

If you can get to correct forces in dynamic simulation you can then export discrete time steps to analyze FEA at those time steps of interest  (it is not going to dynamically deform while in DS).


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Message 8 of 18
FabianNie
in reply to: JDMather

But then I do need additional software, right? And is the direction of the acceleration in the picture correct?

Message 9 of 18
JDMather
in reply to: FabianNie


@FabianNie wrote:

But then I do need additional software, right? And is the direction of the acceleration in the picture correct?


No other software needed if my workflow would work in your application (you should get that book or at least go through all of the built-in tutorials and any YouTube or Skillbuilders you can find on the topic).

 

For your second question I can't really tell anything from that picture.

Can't you build a simplfied dummy assembly or part that illustrates the same behavior of your real work and attach that here?


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Message 10 of 18
FabianNie
in reply to: JDMather

Just made an example and applied an acceleration on one part. The files are attached.

 

Fabian

Message 11 of 18
JDMather
in reply to: FabianNie

I get an error trying to extract your zip.
Did you use Windows to zip or some other software?


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Message 12 of 18
FabianNie
in reply to: JDMather

This is strange. I used 7-Zip. I attached it again packed with 7-Zip but without compression. If it still does not work I'll get another software.

 

Fabian

Message 13 of 18
JDMather
in reply to: FabianNie

That one opens fine - but I'm on my way out the door.  I'll check back tomorrow if someone else doesn't jump in here.


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Message 14 of 18
JDMather
in reply to: FabianNie


@FabianNie wrote:

 I'm a little confused about the direction. The arrow is pointing from the left to the right. I think the part should bend to the other direction. 

Fabian


I think it is a matter of perspective body load acceleration or a force (like gravity). 
I'll let Hugh come along and give a better explaination.


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Message 15 of 18
henderh
in reply to: JDMather

I totally agree with JD, it's a matter of perspective.

 

For your analogy of an acceleration sled, if the box moves to the left, the acceleration force will act to the right.  The "free" corners of the box will deflect to the right.

 

If you were in a car, and it accelerates forward, your head would thrown back and your body pressed into the seat.  Although the direction is forward, the body load from the acceleration is the opposite direction due to the inertia that your body wants to stay "at rest".  A similar thing would be true for going around a corner.

 

If you set up the simulation this way in Dynamic Simulation, you can export the motion loads and view the acceleration body load direction in stress Analysis.  It consistent.

 

Hope this helps...

 

Thanks, -Hugh

 

NG_body_load_acceleration_direction.png



Hugh Henderson
QA Engineer (Fusion Simulation)
Message 16 of 18
FabianNie
in reply to: FabianNie

Sorry for the late reply. Had to take a few days off for family affairs.

 

@ JDMather and henderh: Thank you for your help. I appreciate it very much.

 

@ henderh: Why can you do a stress analysis of an assembly with Inventor? I can do this only with a single component. Is it a new feature of a version later than R11?

 

@ JDMather: Could you point me to a source that describes how to export the forces in a dynamic simulation to an FEA? My book on inventor does not cover simulations and I hope I do not need to buy another book for just one simulation.

 

Fabian

Message 17 of 18
JDMather
in reply to: FabianNie

There are Tutorials built into Inventor. (see attached)

 

 

My guess is that there is probably a Skill Builder too  Help>Learning Tools>Skill Builders & Tutorials.


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Message 18 of 18
henderh
in reply to: FabianNie

Hi Fabian,

 

  We introduced assembly stress analysis in the R2010 release when we switched from the ANSYS based solver to the PlassoTech solver.

 

  R11 was released ~5 years ago and my memory is foggy on the exact steps.  If I remember correctly, the basics of exporting the motion loads in that release were:

    1)  Run the simualtion in DS and pause at the desired timestep

    2)  Press the Export to FEA button and select the part in the graphics

    3)  Choose the load bearing faces in the graphics when prompted in the dialog

    4)  In-place edit the part (key step)

    5)  Enter Stress Analysis and use the import motion loads command.

 

Hope this helps, -Hugh



Hugh Henderson
QA Engineer (Fusion Simulation)

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