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Changing density to reduce solving time

    • Fatah Nugraha
      Subscriber

      Hello. I am conducting a vehicle roll test using the LS-Dyna workbench. I am doing a simulation with a time of 1 s. However, it lasts very long and does not complete. I saw a discussion about changing the density to shorten the simulation time. I multiplied the density a thousand times and the simulation did proceed quickly. But, can you explain more about that? What is the effect? Can the deformation data be retrieved? Does the deformation need to be divided by 1000 since I multiplied the density by 1000 times? Sorry for asking so many questions

    • Sampat Kumar
      Ansys Employee

      Hi Fatah,
      Increasing the density is an option to decrease the simulation time, but it is more related to the mass scaling and CFL time than reducing the simulation time. There is a recommendation that you can increase the density by around 5% for dynamic analysis, and most importantly, it should not change the physics of the problem.
      Explicit solutions do not perform equilibrium iterations to enforce a force balance in the system; explicit solutions rely on energy balance in the system.
      If you increase the mass, then the kinetic energy also increases.
      Kindly follow the link to know more about the mas scaling 
      https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v232/en/wb_adyn/adyn_cont_masscal.html?q=mass%20scaling
      https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v232/en/exd_ag/exd_ag_impexp_solnstability.html?q=mass%20scaling

      Is it possible to reduce the simulation time? Please let me know.

      Regards,
      Sampat

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