Curve Interpolation

fliesenf

Hello,

I tried to include dynamic bearing stiffness in a MBD system. The curves were determined by the producer and should be correctly. In the transient analysis I got the following warning:

I think that means, that the curve is not defined in the necessary region. But these high X values (displacement in mm) should never be reached in reality, because the displacement of a bearing is much smaller (factor 100-1000).

When my comprehension is right (the X values in the screenshot were needed), my static system have to be wrong. Am I right with this assumption or is there another mistake?

Thank you!

Community-Pasted-Attachment-1660639944483.png

Praful

Hello fliesenf

your understanding is right. the model may not have been set up correctly.

1) how are you modeling the "dynamic stiffness" ? Note that when a stiffness for a spring or bushing is not a constant value, it is represented as a Force. So the curve that you are creating should be a Force v/s displacement curve (and not Stiffness v/s displacement).

2) what is the reference for the displacement ? Generally, a displacement function between 2 markers is used. Does the displacement function used matches with the reference that was used to generate the data ?

3) Check the interpolation that you are obtaining (Akima or Cubic) . Does that look good ?

4) check for any other abnormalities in the model. Such as a high mass/inertia value etc. ?

5) It looks like there are several springdampers or bushings which you are representing with a non-linear curve. Just keep one of them active while setting others to a constant stiffness value (Linear in the Springdamper or bushing properties) to figure out what is causing this behavior.

 

Good luck !

Regards

Praful