Model analysis

priyankabhola
priyankabhola Altair Community Member
edited October 2020 in Community Q&A

Hi,

 

i want to regarding model analysis card deatil EIGRL card .

 what is meaning of V1, V2 ,ND.... when should i use  v1 and v2 .difference between v1 and v2. i saw some tutroial online someone use v1 some one use v2.  can you explain in detail.

 

Thanks in advance

Priyanka bhola

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Answers

  • FaroukM
    FaroukM Altair Community Member
    edited March 2020
    Altair Forum User said:

    Hi,

     

    i want to regarding model analysis card deatil EIGRL card .

     what is meaning of V1, V2 ,ND.... when should i use  v1 and v2 .difference between v1 and v2. i saw some tutroial online someone use v1 some one use v2.  can you explain in detail.

     

    Thanks in advance

    Priyanka bhola

    Hi,

     

    First, you are running Real Eigenvalues Analysis using Lanczos solver (EIGRL).

     

    V1 and V2 mean the lower and upper bound of your frequency domain.

     

    ND means the number of roots (number of eigenvalues) of the following equation :

    (-w^2*M - K)*phi = 0

     

    with w refers to the real eigenvalue and phi means the eigenvectors.

     

    Cheers,

  • Nathan_22110
    Nathan_22110 Altair Community Member
    edited March 2020
    Altair Forum User said:

    Hi,

     

    i want to regarding model analysis card deatil EIGRL card .

     what is meaning of V1, V2 ,ND.... when should i use  v1 and v2 .difference between v1 and v2. i saw some tutroial online someone use v1 some one use v2.  can you explain in detail.

     

    Thanks in advance

    Priyanka bhola

    Hi,

     

    As Farouk said, V1 and V2 are respectively the lower and upper frequency bound.

    For example, if you write V1=20 and V2=2000, then it will search for Natural Modes frequency only in this range [20,2000] (according to your unit system, generally Hz).

    ND is to specify the number of roots (so of modal frequencies) you want.

     

    Please find the table attached from EIGRL OptiStruct help. If you combine V2 and ND, it will only compute the minimum number of frequencies allowed by either V2 or ND. 

     

    Regards,

    Nathan

    <?xml version="1.0" encoding="UTF-8"?>Capture.PNG

  • priyankabhola
    priyankabhola Altair Community Member
    edited May 2020
    Altair Forum User said:

    Hi,

     

    First, you are running Real Eigenvalues Analysis using Lanczos solver (EIGRL).

     

    V1 and V2 mean the lower and upper bound of your frequency domain.

     

    ND means the number of roots (number of eigenvalues) of the following equation :

    (-w^2*M - K)*phi = 0

     

    with w refers to the real eigenvalue and phi means the eigenvectors.

     

    Cheers,

    thanks a lot for reply 

  • priyankabhola
    priyankabhola Altair Community Member
    edited May 2020
    Altair Forum User said:

    Hi,

     

    As Farouk said, V1 and V2 are respectively the lower and upper frequency bound.

    For example, if you write V1=20 and V2=2000, then it will search for Natural Modes frequency only in this range [20,2000] (according to your unit system, generally Hz).

    ND is to specify the number of roots (so of modal frequencies) you want.

     

    Please find the table attached from EIGRL OptiStruct help. If you combine V2 and ND, it will only compute the minimum number of frequencies allowed by either V2 or ND. 

     

    Regards,

    Nathan

    <?xml version="1.0" encoding="UTF-8"?>Capture.PNG

    thanks  a lot

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