Frequency response analysis - settings

User: "Mateusz L"
Altair Community Member
Updated by Mateusz L

Hello, I am writing to ask how correctly set FRA analysis?
I've made an example with simple plate:
1.Modal analysis:
<?xml version="1.0" encoding="UTF-8"?>Modal.thumb.PNG.644bf253b9dde77c39d31494d1bfcfcd.PNG

2. FRA analysis:
- frequency function like that (just for example)

image.png.0f8e3b00a4e3658efbc8321a9d10d116.png

- base excitation - acceleration
image.png.ec7a5064b37f5dd08613eeb64c490c56.png

3. Result:
image.png.261c58457f002543c48f33be68a15843.png

Result isn't the same as in modal analysis as I supposed to. I expected peak values in 26Hz, 116Hz, 169Hz where resonace will occur.
 

Somewhere I made a mistake, can anyone help me?

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    User: "GirishM"
    Altair Employee
    Updated by GirishM

    Hi Mateusz,

    Can you confirm if you are using 2019.2 version of SimSolid?

    User: "Mateusz L"
    Altair Community Member
    OP
    Updated by Mateusz L

    Hi Girish,
    yes, I am using 2019.2.0 version.

    User: "GirishM"
    Altair Employee
    Updated by GirishM

    Please try the latest 2019.2.1 release. We fixed a bug related to FRF.

    User: "AlessioMM"
    Altair Community Member
    Updated by AlessioMM

    Hello, I have quite the same problem, using Base excitation (Simsolid latest release 2019.4.1).


    Just considering a simple input (constant acceleration 1m/sec^2) I can't obtain the same results between FEM analysis and Simsolid. Simsolid seems to convert and use the input acceleration in the wrong way respect to traditional FEM.

     

    Frequency-function.JPG.24fb1b50d43931444ea8fc5b5f7e5423.JPGBase-Excitation.JPG.6aa7cb9795e2b74f51a2658f67bab7f6.JPG

     

    Does anyone have already check the right correlation between Simsolid and FEM results in frf acceleration vs freq analysis (Base excitation)?

     

     

     

     

    Hi,

    As shown in the picture below, did you link your dynamic analysis to the conducted modal analysis? and gave proper frequency span?

     

    <?xml version="1.0" encoding="UTF-8"?>Picture1.png