How to obtain the natural frequency of the beam in ANSYS 1

[georg2976]

Dear gentlemen,

I am new in ansys, and I need a help. I want to obtain the frequencies of the beam, for any properties of the beam and any boundary conditions. I need some example how to set parameters of the beam, number of finite elements. Of course, for the beginning I need analyze for free vibration of the beam. We can include rotary inertia and shear. But for the beginning. ANSYS, frequency, settings parameters and boundary conditions.

Regards!!!

Georg

 

[flash3780]

There is a tutorial in the ANSYS help file that covers modal analysis of an airplane wing (which is like a beam). Drill down through the tree on the LHS of the help menu and select: "ANSYS Help System > Mechanical APDL > Tutorials > 8. Modal Tutorial > 8.1 Modal Analysis of an Airplane Wing"

Of course, you could use beam elements as well, but I'd imagine that your model won't be very large either way.

Good luck.

//signed//
Christopher K. Hubley
Mechanical Engineer
Sunpower Incorporated
Athens, Ohio
--

http://engineeringliberty.wordpress.com

 

[flash3780]

Whaddya know? They posted their tutorials online, as well:

http://www1.ansys.com/customer/content/documentation/130/ans_tut.pdf

Check out page 97 (107 in the PDF)

//signed//
Christopher K. Hubley
Mechanical Engineer
Sunpower Incorporated
Athens, Ohio
--

http://engineeringliberty.wordpress.com

 

[Drej]

This should get you started. You can parameterize any value in the commands.

fini
/cle,nostar

/title,Modal Analysis of a Simply Supported Beam
/filnam,beam_modal

/prep7

! ============== PARAMETERS ==================
YOUNGS_MOD = 210e9
SHEAR_MOD = 210e9/2.6
POISSON = 0.3
DENSITY = 2400
ELEMENT_SIZE = 5/100
KP_COORDX1 = 0.
KP_COORDX2 = 5.0
! ============================================

mp,dens,1,DENSITY
mp,ex,1,YOUNGS_MOD
mp,nuxy,1,POISSON
mp,gxy,1,SHEAR_MOD

k,1,KP_COORDX1,0.,0.
k,2,KP_COORDX2,0.,0.

l,1,2

et,1,4
r,1,0.5,4.17E-2,10.42E-3,0.25,0.25,,
RMORE, , ,0.83, , , ,   

lesiz,all,ELEMENT_SIZE
latt,1,1,1
lmesh,all

alls

/solu
DK,1,,0.,,0,UX,UY,UZ ,rotx ,roty , , 
DK,2,,0,,0,UY,UZ ,rotx ,roty , , ,  
alls
d,all,uz,0. 
d,all,rotx,0. 
d,all,roty,0. 

ANTYPE,2
MSAVE,0 
MODOPT,LANB,5   
EQSLV,SPAR  
MXPAND,5, , ,1  
LUMPM,0 
PSTRES,0
MODOPT,LANB,5,0,0, ,OFF 

alls
solv
save
fini
/post1

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[georg2976]

Dear Drej

Thank you very much for this code. But where can I type this code and I wanted to change something (dimension of the beam) and obtain then the eigenvalues problem? How. If you have some .pdf manual for example, very simple.

Thank you in advance!!!

 

[Drej]

You can read this code in using File -> Read Input From -> and then choose the file that this code contains. The beam properties can be changed using the real constant in the code. Sounds like you will need to take some time to learn ANSYS and APDL, but most importantly (before you start punching numbers) understand modal analysis. There are many examples available across the web and also within the ANSYS online manual (the post above is a good start).


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[georg2976]

Dear Drej,

It is clear, but where I can set the boundary conditions, dimensions of the beam in your file? Also I would like to get the natural frequencies for free vibrations.