×
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 describe load step after using D command in transient analysis?

how to describe load step after using D command in transient analysis?

how to describe load step after using D command in transient analysis?

(OP)
Hi every body
I had  1560 acceleration versus time data(ELCENTRO EARTHQUAKE DATA) and I wanted to do a transient analysis, after I saw more topics about seismic and transient analysis I understand that I have to convert my acceleration data to displacement so I use *VOPER and INT2 commands to do this and now I have displacement versus time data and I intend to do a transient analysis and using this data as displacement load at the base of my Structure, then I made a table using *Dim and set it as displacement load in my problem(D command),but I don't know how to set up my transient analysis option, do I have to describe separately a load step for every time and displacement data in solution control box in transient analysis? My data like this: time1, dis1 time2 dis2.......
Do I have to do like this: load step one?time1 dis1, load step two?time2 dis2…..?
If yes, how can I do this in ansys? Do I have to use APDL and do loop COMMAND to do this? Please explain it how?
Please write a sample APDL.
Second question:
the third frequency of my structure is  2.7414  and I want to set time step size ,is it correct that I use 1/20f as time step size ,and is it enough to solve the problem or I have to turn on automatic time steping and max and min time step size?
I want to do a transient analysis because of NON LINEARITY of my structure; do I have to set any setting in nonlinear tab of solution control box?     
thanks

RE: how to describe load step after using D command in transient analysis?

(OP)
I intend to do a transient analysis and using dis versus time data as displacement load at the base of my Structure,I make a table using *Dim and set it as displacement load in my problem(D command),but I don't know how to set up my transient analysis option, do I have to describe separately a load step for every time and displacement data in solution control box in transient analysis? My data like this: time1, dis1 time2 dis2.......
Do I have to do like this: load step one-->time1 dis1, load step two-->time2 dis2…..?
If yes, how can I do this in ansys? Do I have to use APDL and do loop COMMAND to do this? Please explain it how?
Please write a sample APDL.

RE: how to describe load step after using D command in transient analysis?

(OP)
please help me if someone knows it.
thanks in advance
regard

RE: how to describe load step after using D command in transient analysis?

Hi,

i wrote below a samle of code with basic setting, you must set another ones by yourself. Also set the minimum time increment (i set freq/200 for example) as you desire. In "node(x,y,z)" replace x,y,z with global coordinates of node for which is displacement value being applied.

freq = 2.7414
*dim, values,,1560,2

fini
/sol

antype,4

*do,i,1,1560
  time  , values(i,1)
  nsubst, freq/20,freq/200,freq/20
  d,node(x,y,z),,values(i,2),,,,ux
  solve
*enddo

fini
/post26

Regards,
lubo

  

RE: how to describe load step after using D command in transient analysis?

(OP)
hi SKJoe
thanks alot for your response, i do every things that u said but again like my past problem when i check the result at nodes that I set the displacment load, there is difference between my load data and the data that shown in
post26 result plot.
I don't know why it happened,please help me why there is diffrence between them(load displacement and result displacement exactly on the same nodes).

thanks again
regards

RE: how to describe load step after using D command in transient analysis?

(OP)
hi SKJoe
thanks alot for your response, i do every things that u said but again like my past problem when i check the result at nodes that I set the displacment load, there is difference between my load data and the data that shown in
post26 result plot.
I don't know why it happened,please help me why there is diffrence between them(load displacement and result displacement exactly on the same nodes).

thanks again
regards

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