Learning Forum

[Anita Amirsardari]

Hi ANSYS community,

I am trying to run incremental static analysis in ANSYS Mechanical APDL. I am not sure how to write the code using a loop command (using “*do”). I need to write a loop command (rather than directly solving by defining the number of subsets etc) because after each solved step, I need to review the stresses and strains in the model and use the ekill command if the threshold is exceeded.

A short example of my script is below. I like to apply a displacement of 20mm to the selected nodes in 100 steps. However, in my current code, in the first load step the 20mm is applied, rather than 20/100 = 0.2mm.

Could someone please advise how I can correct my script?

 

Many thanks,

Anita

 

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Apply load on selected nodes !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
NSLA, R,1
NSEL,R,LOC,X,-100, 100
NSEL,R,LOC,Y,300
NSEL,R,LOC,Z,27
CM, n0, NODES
D,n0,UY,20, , , , , , , , , 
ALLSEL,ALL
!*
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Define Solution Controls !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
/SOLU
!total number of steps for solve
    steps=100
    TIME_END=1
    timeinc=TIME_END/steps
    time,timeinc
    solve
*do,ICOUNT,1,steps-1
  /solu
  allsel,all
  time,timeinc*ICOUNT+timeinc
  solve
  finish
*enddo

[Ashish Khemka]

Hi,

Instead of defining loadsteps you can define equal substeps. Also, refer to the following verification maula from Ansys Help which might help ypu:

Ansys Mechanical APDL Verification Manual

NSUBST (ansys.com)

Regards,

Ashish Khemka

[Anita Amirsardari]

Hi Ashish,

Thank you very much for the suggested references. I am unable to find an example in the Verfication Manual for which a loop is used to incrementally increase the applied load. 

I am able to use NSUBS to run the analysis successfully, however, this doesn't allow me to create a loop command where I can check the stresses at each substep in order to implement ekill if required. 

Would you please be able to provide an example where the load is applied incrementally but at each substep it is possible to run a *do command to check element stress and execute ekill if the stress exceeds the threshold? 

Many thanks,

Anita

[Ashish Khemka]

Hello,

Please see if the links below help:

Delete cells with stress above a certain value – EKILL – APDL (ansys.com)

Element Alive and Kill Commands with 2D Shell Models (ansys.com)

Regards,

Ashish Khemka