Phase graph is discontinuous, why?

[Frankie183]

Hi all!

I've got a question, I perform a Steady state analysis and have exported the phase and magnitude graph.
However, there are some massive discontinities in it, while I have a lot of points in the step definiiton between the lower and upper frequency..

Any Idea where these discontinities come from?

Greetings,

 

[FEA way]

Some details of the simulation will be needed to help with this issue:
- do you perform steady-state dynamics analysis on a fractured specimen ? What is its goal ?
- what kind of structure is that and how is it loaded ?
- is the simulation based on some research paper ? If yes, the title will be useful.

Also, please attach some screenshots showing the model and results (contour plots, deformed shape), if you can.

 

[Frankie183]

Yes,

it's a simple cantilever beam subjected to a vertical load on the end.
In the specimen, a delamination is present. I increase the delamination for every steady state analysis. That's why you see a shift in the resonance frequency, as the stiffness decreases.
It's a novel research, so the paper is not there yet. I unfortunately can not show the screenshots.

Any clue to the discontinuity?

 

[FEA way]

I think that the best you can do is take a close look at the deformed shape and contour plots for frequencies around which these discontinuities occur. Animations and XY plots of other output variables (especially energies) might be helpful as well.

Generally speaking, I would expect some discontinuities in such analysis as it involves fracture mechanics. Discretization may have large impact here so try refining the mesh.