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Is there any way to set a variable for initial conditions of joints that have been applied motion in adams solver script (.acf)?

s.kuris
Here is the example of my simulation script.
I would like to set a variable for ICDISP.
 
MOTION/4,JOINT=14,TRANSLATION,VELOCITY,ICDISP=-25,FUNCTION=0
MOTION/3,JOINT=12,ROTATION,VELOCITY,ICDISP=2.532d,FUNCTION=0
SIM/KIN, END=2, STEPS=360
MOTION/4,JOINT=14,TRANSLATION,VELOCITY,ICDISP=-25,FUNCTION=0
MOTION/3,JOINT=12,ROTATION,VELOCITY,ICDISP=0d,FUNCTION=0
  • 0
    Hi,
    Have a look in Adams Help to the following:
    Adams Basic Package > Adams View > Adams View > Building Models > Joints > Idealized Joints
    Adams Basic Package > Adams View > Adams View > Dialog box - F1 help > J - O > Joint Initial Conditions
    Adams Basic Package > Adams View > View Command Language > part > part modify rigid_body initial velocity
  • 0
    Thank you for your respond and help.
     
    I have looked at those pages on help, however i would like to do it on .acf script.
    My question is it possible to do it on .acf and if it is possible could you give some example ?
  • 0
    No, ACF, as well as ADM does not know about design variables (they are evaluated the moment you submit your simulation). And you can't reference a solver variable either.
     
    But what you are trying to do in your example above is to jump the rotational motion from 2.532° to 0° at t=2. That should cause a huge spike in all internal forces (looks like your model is kinematic constrained with 0 DOF so it might work).
    But you can as well define the motion in the model as a displacement function:
    FUN=IF(time-2:2.532d,0,0)
    and you don't have to change it in the acf at all. And here you can use design variables.
    Or use a little nicer function:
    FUN=STEP(time,1.99,2.532d,2.01,0d)
     
  • 0
    Hello JSlat,
     
    Yes you are right the system has 0 DOF.
    Actually it is a simple steering system including hooke joints. So i am achieving in here calculating non-uniformity in different steering positions.
    In order to simulate all positions conditions and run optimization study, in the past i have done this kind of approach. Actually system is working so far, however i would like to also add some parameters on initial condition i stucked there.
    Thank you for your advice, i will use that approach. Raised hand
  • 0
    Yeah, I did that study around 31 years ago Grinning
    It is easier to parameterize the model in the correct way and run the optimization directly in View.
    It is a little pickling to get the parameterization of the hooke joints and clocking angle correct, but once it is done, you have a model with a couple of hardpoints (2, 3 or 4 depending on how you want to work with the model) that you can move + one variable for clocking angle to change. Then I typically run one revolution (on the steering wheel) with constant angular velocity and has an objective for max variation of the angular velocity of the output shaft.
     
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