×
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

Nonlinear material input

Nonlinear material input

Nonlinear material input

(OP)
Hello all,
I have a problem with defining nonlinearity to a material. first i have defined
MP, EX,   1, 206000e6
MP, PRXY, 1, 0.3
MP, DENS, 1, 7850
for steel, and then i input and
TB,KINH,1,1,8                  ! Activate a data table
TBTEMP,
TBPT,,0.00   , 0.0             ! Strain = 0.00, Stress = 0.000
TBPT,,0.0029 , 320.7e6         ! Strain = 0.0029, Stress = 320.7
TBPT,,0.0092 , 350.6e6
TBPT,,0.0356 , 381.9e6
TBPT,,0.1006 , 411.9e6
TBPT,,0.2056 , 426.1e6
TBPT,,0.2518 , 420.2e6
TBPT,,0.2812 , 387.0e6
TBPT,,0.2975 , 331.6e6
when i start the solution it comes with this error:
 *** ERROR ***                           CP =      23.516   TIME= 16:21:25
 For material 1 at temperature 0, the initial slope of the stress-strain
 curve based on the TB,KINH table ( 1.105862069E+11 ) is less than EX (  
 2.06E+11 ).

I tried not to define the EX, and the it says that EX is not defined...
If anyone have an idea how can i fix this i'll be very grateful.
Thanks

RE: Nonlinear material input

Hi

For the first stress strain you need to add values that
Ex=Stress/Strain =206000e6

Ex=320,7e6/0.0029 = 110586e6 This can't be smaller then 20600e6
So change the stress/strain values.

Garry

RE: Nonlinear material input

This depends on what is accurate
I mean if you think that Youngs Modulus is accurately measured
Keep E=206000e6
and modify your first yield point by
206000e6 x 0.0029 = 597.4 which is much more than the value you have fed..i.e 320.7
I have strong feeling your plastic data is wrong or say incompatible with youngs modulus
I feel that most likely the strain value is wrong ,
Or may be you have got plastic values for different material
PLease check your data once again ..for analysis sake
If data is right then see which is more accurate
If modulus is right you have to modify first yield value
If you have confidence on Plastic data modify the youngs modulus as stress/strain for first point i.e. 1.105862069E+11
Now can you let us know the material so we can judge the rough value of E
Bythe way ansys can not solve without value of E, any FE solver can not
Thanks,
Dev

RE: Nonlinear material input

Balu,

Solution is very simple.
Your material table starts when material goes plastic.
So remove first line of table and replace with a value
ON your elastic line.

TBPT,,0.00   , 0.0      !< Remove this line
TBPT,,0.0014563   , 300      !< Replace with this


(note 0.0014563 = 300e6/206e9)

Regards,

RE: Nonlinear material input

(OP)
Thanks eelco71,
I've done something like it but not exactly...when i define EX, I use the value of  320.7e/0.0029.
And its working now:)
But after some thinking, It looks like your decision is better...may be I'll do it:)
Thanks again!!!

RE: Nonlinear material input

BY this you assume that
Your plastic data was incorrect

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