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HHT Solver, Hmin Error

jsph_inc
Hi All,
 
I am running the HHT solver for an ADAMS/View model. The simulation errors because the minimum step size is reached. Up to that point the step size is reasonable around 1E-5 / 1E-6 but then hits the minimum.
 
Reducing Hmin does not solve the issue as the solver reaches the new Hmin value and errors.
 
The only work around I have found is adjusting the solver error. I've never encountered this with GSTIFF. The model is contact heavy.
 
Does anyone know what causes this with HHT? Any suggestions to avoid this?
 
joe.
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  • 0
    Hi Joe, which version of Adams are you using? In 2023.2 (I think) adaptivity was introduced in the C++ solver.
    Setting the parameter ADAPTIVITY=1e-9 (a parameter under the INTEGRATOR statement) typically prevents this from happening without any ill effects.
    Adaptivity defaults to 100*HMIN but as HMIN is so small for HHT, it barely helps without explicitly setting it to something meaningful (like typical_timestep/1000).
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  • 0
    Hi Joe, which version of Adams are you using? In 2023.2 (I think) adaptivity was introduced in the C++ solver.
    Setting the parameter ADAPTIVITY=1e-9 (a parameter under the INTEGRATOR statement) typically prevents this from happening without any ill effects.
    Adaptivity defaults to 100*HMIN but as HMIN is so small for HHT, it barely helps without explicitly setting it to something meaningful (like typical_timestep/1000).
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