Contact in FRF

Beta

Hi,

 

I am trying to perform a FRF analysis in a simple model. However, there are some contacts in this model.

 

I know that SLIDE contact type could only be used in a Nonlinear analysis so the it is not possible to use it for FRF anaylysis.

 

Is there any method or some way so I can solve this problem.

 

Thank you! 

Rahul Rajan_21763

You can run FRF with NLSTAT analysis type. PFA fem deck for same.

Unable to find an attachment - read this blog

Beta

Hi Rahul,

 

Thank you for your answer. 

joseph_21332

Hi Rahul R

But however the Preloaded stress and strains are not carry forwarded from the NL substep to modal or FRF analysis.

if SPC Forces are carry forwarded then the results who be different

Adriano_Koga

joseph_21332 said:

Hi Rahul R

But however the Preloaded stress and strains are not carry forwarded from the NL substep to modal or FRF analysis.

if SPC Forces are carry forwarded then the results who be different

Just a quick coment in the first post:

SLIDE contact can be used in both linear and non-linear analysis, but it will act differently.

In linear models (static, modal, FRF,..), the contact status will not change during the analysis, meaning that it will not open or close due to traction/compression effects. There will be still sliding between the parts, frictionless, BUT they won't separate.

For full NL models, the SLIDE contact will be a frictionless contact but its status might change depending on the loading conditions, if they tend to open or close the contact.

 

Now, concerning PRELOAD.

Using PRELOAD into your FRF loadcase will carry Geometric Stiffness resulting from the preload loadcase.

 Please take a look at the attached PDF from the Help.

It is important to note that, while the prestressed linear analysis includes the
effects of preloading as a weakening ora stiffening of the structure, the results
from the prestressed analysis do not include the preloading results. Forexample,
the displacements from prestressed linear static analysis do not include the
preloading displacements. Inorder to get the overall deflection/stresses of the
structure, the displacements/stresses from the prestressed linearanalyses have to
be carefully superposed with the preloading displacements/stresses while
post-processing.Particularly, while post-processing complex results from
prestressed direct FRF, the correct approach would be tofirst obtain the complex
results for a certain phase and then superpose the appropriate preloading result.
Any othersuperposing approach would lead to incorrect results.