Frequency load in HyperMesh using Nastran solver

Koushik Chandrashekhar_21806

Hi all,   I need to apply frequency as load in HyperMesh tool using Nastran solver . But I do not know how to apply frequency as load on a given component. I need help on this matter, Please help.

Adriano A. Koga

Hi @Koushik Chandrashekhar

 

I assume you're trying to build a FRF analysis (Sol 111 or 112).

You might reference to OptiStruct tutorial for FRF, as it is pretty similar to Nastran Setup.

 

Besides these steps from the tutorials, you will need to add 'SOL 111 or 112' card and make sure results are requested in Punch or OP2 formats, instead of H3D.

 

As you already use HM, it would be easier to run this in OptiStruct, by the way.

Advanced Small Displacement Finite Element Analysis

 

• OS-T: 1300 Direct Frequency Response Analysis of a Flat Plate
  This tutorial demonstrates how to import an existing FE model, apply boundary conditions, and perform a finite element analysis on a flat plate.
• OS-T: 1305 Modal Frequency Response Analysis of a Flat Plate
  This tutorial demonstrates how to import an existing FE model, apply boundary conditions, and perform a modal frequency response analysis on a flat plate.

 

Koushik Chandrashekhar_21806

Hi Adriano,

 

Thank you very much.

I received this query from a user and I gave him this post link for further updates.  

Xavier

thank you, sir

small displacement finite element analysis section was very helpful, this section  only gives displacement values for varying loads with respect to time.

but i require  stress and strains also to that corresponding displacements generated.

i tried many control cards to print stress and strain, but there was no use.

Irrespective of so many cards  selected, the output file (f06  file) only contained displacement for varying load with respect to time.

please help me in this matter.

 

Adriano A. Koga

i believe adding PARAM,POST,-1 or -2 might help you.

 

Ohterwise, add manually the Cards (something like this)

 

STRESS(PRINT) = ALL

STRAIN(PRINT) = ALL

 

depending if you want Magnitude or Phase, or Real Imaginary, you will need to adjust.

Usually people also request this in Punch/PLOT Format, to plot in HyperGraph.

 

I'm not super familiar to Nastran outputs, but you migh look here and then find these card in HyperMesh.

https://femci.gsfc.nasa.gov/sine_vib/

 

Take care with FRF results size as depending on your  model size it might get huge.

So usually people request results only for desired elements/nodes, creating a SET for output and selecting it.

Xavier

 

please go through files attached 

 

the output of dynamic analysis is 1000 times greater than that of static analysis

I have verified for  input units in both the case the  E, G, Nu is the same , but yet there  is drastic change in dynamic output.

 

 

 

 

 

 

 

 

Unable to find an attachment - read this blog

Adriano A. Koga

hi,

 

by your description your dynamic load (transient) is using this table shown above, with a ramp from 0 to 1000.

This means that you're multiplying your forces (total 1000N) times the TABLED1 value, thus resulting in a load 1000x higher than your statics.

 

Your table could be changed to have a maximum value of 1.0 multiplied by your forces (~1000N)

Xavier

thank u sir,