Load condition that varies with output (e.g. rotation of a reference point)

[FinlayA]

Hi,

I'm using Abaqus 6.10.

I have attached a picture that illustrates a simplified version of my problem. The actual problem is different but if I can solve this generic problem I should be able to tackle mine.

I am essentially looking to apply a moment to a hinged component (e.g. the bar pinned at its bottom in the diagram) but I want this moment to vary with the rotation of the component, i.e. the moment is a function of the angle of rotation.

So I basically need the effect of a torsional spring as shown in the diagram. I am wanting to begin my simulation/analysis with the bar in the vertical position, with the spring compressed, so when the simulation begins, the bar begins to accelerate as the spring returns to its stable position.

Currently my best solution has been to apply the average moment of the swing, however this is not ideal as the component impacts another component on its swing down. I am aware you can add spring elements, although I have not seen the capability for torsional springs, or to have a spring that starts the simulation in its compressed state.

As I'm running an explicit, dynamic analysis, it would be perfect if I could define the moment using the rotation of a reference point at the hinge, so that this updates every increment.

If anybody knows of a method for doing this, or a different but useful method, I will be very appreciative!

Many thanks,

Finlay

 

[akabarten]

Hi Finlay

To define load dependent on rotation you need to use user amplitude defined with VUAMP subroutine + sensor output.
For details please take a look into Abaqus documentation:
- Abaqus User Subroutines Reference Manual, 1.2.7 VUAMP User subroutine to specify amplitudes.
- Abaqus Analysis User's Manual, 4.1.3 Output to the output database, Sensor definition in Abaqus/Standard and Abaqus/Explicit

Regards,
Bartosz

 

[FinlayA]

Thanks Bartosz,

I've had a look at that seems to be what I'm after. It's maybe a bit outwith my skills, I have been operating using the Abaqus/CAE pre-processer and haven't attempted to use any code before but I'll give it a shot.

Thanks for your help.

 

[IceBreakerSours]

Unless you haven't already, you will have to install a few software programs before you can do any coding. Check the forums and Simulia website for more on this.

http://www.eng-tips.com/faqs.cfm?fid=376

http://www.eng-tips.com/faqs.cfm?fid=1083