×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

How to do modal analysis with damping of material?

How to do modal analysis with damping of material?

How to do modal analysis with damping of material?

(OP)
I want to obtain the modal damping with material damping input....looking forward help....

RE: How to do modal analysis with damping of material?

Hello!

You could use as method for extraction
DAMPED or QR DAMPED

Best wishes,
Juzz

-------------------------------
Justin Onisoru
Researcher
Romanian Academy
Institute of Solid Mechanics
-------------------------------

RE: How to do modal analysis with damping of material?

(OP)
Thanks the answer from Justin Onisoru.
I have tried the DAMPED and QR DAMPED method. But the result is so strange, I got no any complex frequency.
I paste the operations here...
--------------------------------
/PREP7  
!*  
ET,1,SHELL63
!*  
!*  
R,1,4e-3,4e-3,4e-3,4e-3, , ,
RMORE, , , ,
RMORE   
RMORE, ,
!*  
!*  
MPTEMP,,,,,,,,  
MPTEMP,1,0  
MPDATA,EX,1,,1e9
MPDATA,PRXY,1,,0.3  
MPTEMP,,,,,,,,  
MPTEMP,1,0  
MPDATA,DENS,1,,1.5e3
MPTEMP,,,,,,,,  
MPTEMP,1,0  
MPDATA,DAMP,1,,0.009
RECTNG,0,0.5,0,0.5,
!*  
LESIZE,ALL, , ,20, ,1, , ,1,
amesh,all   
FINISH  
/SOLU   
!*  
ANTYPE,2
!*  
MODOPT,DAMP,30  
EQSLV,FRONT
MXPAND,30, , ,0
LUMPM,0
PSTRES,0
!*  
MODOPT,DAMP,30,5,5000, ,OFF
/STATUS,SOLU
SOLVE
--------------------

RE: How to do modal analysis with damping of material?

Hello, enjoywithme!

I run your input and it seems to work pretty well.
I obtain 30 frequencies (not all are complex) but it's ok.
So, this is my advice:

1) At the beginning of your input add a command that redirect your output to a file:

/output,file_name,extension,path (default to current directory),mode_of_writting (overwriting or append)

but /output,output,out will be enough

List this file and you will see the frequencies (preceding participation factors calculus)

2) Ifyou don't want to write the output in a file when you open "Results summary..." under /post1 you will see that every substep appears twice. First is the real part, second is the imaginary part.

Best wishes,

Juzz
-------------------------------
Justin Onisoru
Researcher
Romanian Academy
Institute of Solid Mechanics
-------------------------------

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources