Frequency response Function : Mobility for somepoints

Hi Pratik,

Please refer to Frequency response function tutorial on our help documents.

OS-1300: Direct Frequency Response Analysis of a Flat Plate

OS-1305: Modal Frequency Response Analysis of a Flat Plate

In addition refer to RLOAD2 card (used in above mentioned tutorials) to learn how to apply velocity as a freq function.

 Step 8: Create a Set of Frequencies to be used in the Response Solution
 

can you elaborate this steps? does is it calculate the response for only this 49 freqencies (20 hz -1000 hz)

Modal frequency response : does it used some Modal matrix reduction method? any  literature  for optistruct about this method?

Can i use EIGRA instead to EIGRL for Mode frequency extraction

Hi Pratik,

Yes, response is calculated from 20-1000Hz.

You can use EIGRA for modal FRA. You can refer to OptiStruct user guide form more information on FRF analysis.

Altair OptiStruct > User's Guide > Structural Finite Element Analysis > Solution Sequences:

Hello Prakash

In Step 5:  Create a Unit Load at a Point on the Flat Plate

   7 Uncheck all the dof's; except dof3, and click the = to the right of dof3 and enter a value of 20.

what dies the value 20 stand for? Isn,t it unit load?

Regards

Pratik

Pratik,

that is the load/exitation you are giving in Z-direction.

If you are giving load type as enforced displacement for instance, then the node will be displaced by 20 units.

OS-1305: Modal Frequency Response Analysis of a Flat Plate

Hello Prakash

so what exactly is Modal Frequency Response , how does it differ from drect frequency response

for example  If i want velocity response between excitation frequency between say 1000 to 2000 hz , but i want response only at eigen frequncies in this range  should i do Modal Frequency response analysis?

OptiStruct > User's Guide > Structural Analysis:

Hello Group ,

I want to have value of frequency response function Impedance defined as (Acceleration / force) at some points on my structure.

I am doing modal frequency response analysis with optistruct. How do I go about it

Also Suggest Control Cards and other inputs