Criterion for Modell Validation/ callibration

[engg35mechie]

Hallo Group

I am new to NVH simulation.

I have a component tested for vibration. From the test involved measuring Frequency response function (Mobility)FRF on 6 points on the modell. So I have plots of FRF values at Six points on the modell. Using this I want to calibrate My FEM model (with hypermesh/optistruct/hyperstudy). What are techniques to callibrate such modell. I have come across Modal assurance criterion (MAC) and Model updating technique. can you enlighten me about such method.

Thanks and Regards
Pratik

 

[GregLocock]

It would take too long in a post, try any link that discusses correlation of modal analaysis models

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[engg35mechie]

Hello Greg


I have have been going through some post and then some scientific papers. And i believe that FDAC is possible way for correlating and Model updating in my case.
Reasons
1) It takes into account frequency shift
2)FRF can be directly used used for corelation without extracting modal parameter like (Mode shape , Damping etc)as against MAC. especially I dont know how exactly to extract mode shape from a FRF (Mobiltiy) data (attached file I have FRF at Six such points).

But i am confused as to how do you get the values of conjugate of the FRF (as refered in

http://sem-proceedings.com/15i/sem....ion-Technique-Model-Correlation-Updating.pdf)

because all my FRF values are real coreesponding to each frequency.( I dont get which matrix should I transpose)
Also what exactly is FRF matrix (coloums= fRF value at various measured points and row = frequency steps where responses are measured

Thanks and Regards.

 

[engg35mechie]

PS: I am validating the model in range 0 to 200 hz. Should I take the frequency values at resonance for validation with FDAC or any values at suitable interval will be good enough.

 

[GregLocock]

FRFs should be complex.

Personally I think there is less to that paper than meets the eye


Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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