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Static equilibrium

Hamed Hani
Hello Adams Community,
 
I am using Adams MaxFlex to run a nonlinear simulation.
 
I am generating the bulk data file in my code and importing the resulting `BDF` file into my model.
 
My model runs perfectly fine when I use a coarse mesh size like this image(the diameter of the circle is 4 cm):
5
But, as soon as I try a finer mesh size (dividing by 2) like this image, I get static equilibrium simulation convergence error(I don't change anything else about the model).
10
I tried to tweak the solver settings as it is suggested in this article:
 
 
I tightened and loosened the limits on translations (TLIMIT) and rotations (ALIMIT) while I relaxed the error, but had no success getting the simulation to converge. I increased the MAXIT value for convergence, but still no success.
 
Does anyone have any idea what might cause this problem?
 
solver
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  • 0
    How about trying the good old funneling technique ?
    I.e. a consecutive row of sim/sta commands starting with "loose" parameters getting "stiffer" ?
     
    Like:
    EQUILIBRIUM/error=10,stability=5,imbalance=10
    sim/stat
    EQUILIBRIUM/error=1,stability=1,imbalance=1
    sim/stat
    EQUILIBRIUM/error=0.1,stability=0.1,imbalance=0.1
    sim/stat
    EQUILIBRIUM/error=0.01,stability=0.01,imbalance=0.01
    sim/stat
     
    Generally speaking ADAMS static solver isn't what I'd call perfect or satisfying all customers needs. It's more like a capricious diva.
    Especially it doesn't like things creating sharp gradients over a short distance like contacts or flex-bodies or worst of all contact between flex bodies.
    In this case it may help changing the length units.
     
    Whenever I had models that still don't find equillibrium, I gave a sh... and just cut off the first few seconds of the analysis if possible.
     
Reply
  • 0
    How about trying the good old funneling technique ?
    I.e. a consecutive row of sim/sta commands starting with "loose" parameters getting "stiffer" ?
     
    Like:
    EQUILIBRIUM/error=10,stability=5,imbalance=10
    sim/stat
    EQUILIBRIUM/error=1,stability=1,imbalance=1
    sim/stat
    EQUILIBRIUM/error=0.1,stability=0.1,imbalance=0.1
    sim/stat
    EQUILIBRIUM/error=0.01,stability=0.01,imbalance=0.01
    sim/stat
     
    Generally speaking ADAMS static solver isn't what I'd call perfect or satisfying all customers needs. It's more like a capricious diva.
    Especially it doesn't like things creating sharp gradients over a short distance like contacts or flex-bodies or worst of all contact between flex bodies.
    In this case it may help changing the length units.
     
    Whenever I had models that still don't find equillibrium, I gave a sh... and just cut off the first few seconds of the analysis if possible.
     
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