General Mechanical

General Mechanical

Varying pressure after certain timestep with command

    • Gradientz
      So I am trying to create a varying pressure over a distance after a certain timestep.
      I would use the pressure with respect o a independent variable ("Direction") If it was only one time step.
      In this case I have a Cylinder between two plates that is subjected to bolt pretension during the first timestep then locked for the rest of the timesteps.
      After the first time step I'd like to apply a varying pressure on a specific distance after the bolt pretension timestep.
      I have attached a picture with the "concept". The code below is different, I have skipped the bolt-pretension and just want to make something work.
      I have tried following:
      Create a new coordinate system in the "beginning" of the location with CSYS name 888
      Created a named selection
      And tried to use command SF,"Surface","Pres","%table%
      Also tried using SFE with less success, my guess is that the issue with the code below is that I haven't found a way to specify that I want the pressure to act normal to the element face AND along the x-axis (specified in my *DIM) which is in the length direction of the cylinder.
      Tried to force it with "SFCONTROL" without success.
      Any ideas are appreciated!

      CSYS,888 !Coordinate system set to "manual"
      *DIM,grad,table,5,2,1,X,TIME !Five timesteps, two locations, one plane. Defined x-direction and TIME
      *SET,grad(0,1) , 0 !In this case no bolt pre-tension just variying pressure over multiple timesteps
      *SET,grad(0,2) , 1
      *SET,grad(0,3,1) , 2
      *SET,grad(0,4,1) , 3
      *SET,grad(0,5,1) , 4
      *SET,grad(1,0) , 0 !With respect to new coordinate system
      *SET,grad(2,0) , 15.5 !End distance
      !LOAD start grad
      *SET,grad(1,1) , 0.0
      *SET,grad(1,2) , 1.0
      *SET,grad(1,3,1) , 2.0
      *SET,grad(1,4,1) , 3.0
      *SET,grad(1,5,1) , 4.0
      !Load end grad, Taper down to same value for each timestep
      *SET,grad(2,1) , 0.0
      *SET,grad(2,2) , 1
      *SET,grad(2,3,1) , 1
      *SET,grad(2,4,1) , 1
      *SET,grad(2,5,1) , 1
      EDIT: Had issue attaching image, uploaded instead
    • Chandra Sekaran
      Ansys Employee
      Why not apply the load as only a function of direction but 'deactivate' the load in the first load step so it is not used?
    • Erik Kostson
      Ansys Employee
      Hi - so no need for commands -
      you can do what you are trying to do by having two steps, and then defining natively the pressure load as shown below, that varies along z (or whatever direction one needs) and is deactivated in step 1 (via Scale in tabular data):

    • Gradientz
      Jesus, If that is so simple I will punch my self. Will try spon5! Nevertheless learning the commands would be appreciated!!

      Thanks !
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