# Model analysis

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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.

Priyanka bhola

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1 hour ago, priyankabhola 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.

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,

priyankabhola and PrasannaK like this

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On 3/28/2020 at 2:55 PM, priyankabhola 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.

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

priyankabhola likes this

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On 3/28/2020 at 8:53 PM, Farouk Maaboudallah 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,

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On 3/30/2020 at 3:16 PM, Nathan 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

thanks  a lot