Dynamic Simulation of Extension Springs

[rob.j.ross]

In the dynamics simulation mode of Inventor 11, has anyone modeled an extension spring with an initial tension?  When entering springs is seems that I can choose the spring rate only.  The initial tension wound into the spring shifts the spring's force by the initial tension.  Can this force shift be modeled with the spring tool?

[henderh]

Hi Rob,

  You can specify the "Free length" length in the spring's properties (see attached image).

  This will determine the tensile or compressive preload, if the current (or initial) distance between the two defining verticies is different .  As you've found, you cannot input the preload directly.

  Please let us know if you have any additional questions, comments or suggestions.

Thanks, -hugh

[stephen.kosek]

Adjusting the free length only works for one position of the spring.  I am stretching the spring six inches while the part is rotating.  I am trying to use the unknown force to rotate the part, but without an initial tension in my spring, the unknown force result is not accurate. 

[JDMather]

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@stephen.kosek wrote:

  I am trying to use the unknown force to rotate the part, but without an initial tension in my spring, the unknown force result is not accurate. 

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Attach your assembly here.

[stephen.kosek]

The original post for needing initial tension in springs was 10 years ago.  Has there been any software updates to this situation?

[dszego]

I'll add that in Inventor 2020, there's still no way to ground something at one end of the spring, move something at the other end of the spring, and have the spring stretch or compress.

[JDMather]

Attach your assembly here.

[dszego]

Hi, thanks for taking the time to reply. Here's a cut down version of the assembly in question.

[JDMather]

For those who might come across this old thread through search - I am going to continue the new discussion in this thread (see link below) as the previous posters did not choose to continue the discussion and made some incorrect statements that were never corrected since they did not Attach their datasets for illustration of the misconceptions.

In particular @stephen.kosek should have posted files for clarification.  Spring force in Inventor Dynamic Simulation works exactly like it does in the real world.

https://forums.autodesk.com/t5/inventor-forum/stretching-an-extension-spring-made-with-the-generator...