LS Dyna

LS Dyna

S-ALE Fails When Using MAT_ALE_INCOMPRESSIBLE

    • patjoy
      Subscriber

      Hi Everyone,

      I am trying to do a simple bore in a box simulation where a dam of water is allowed to flow around in side a box, however, the simulation keeps failing with the following error:

       *** Error 40660 (SOL+660)

         The laplacian diagonal term for the element 1

         is zero. It usually occurs when the nodes of this element

         are constrained in all directions

      The simulation makes just past the storage allocation lines then the error causes the simulation to fail before a run-time estimate is presented.

      I am not exactly sure what this error means as even when I remove any constraints from the model I still get the same error. The .k file is attached but how I defined the materials is as follows:

      *MAT_ALE_VACUUM - to model the air, section SOLID, ELFORM = 6

      *MAT_ALE_INCOMPRESSIBLE - to model the water, section SOLID, ELFORM = 6

      I filled the S-ALE mesh using the *INITIAL_VOLUME_FRACTION_GEOMETRY card.

      Does anyone have any idea why this model fails to run?

    • ido
      Ansys Employee
      Hello PatJoy,nELFORM=6 is single mat Eulerian. You cannot model 2 ALE mats with it. It is obsolete because to do FSI effectively you need ELFORM=11=multi-mat-ALE (MMALE) formulation where you have both water and air in the the domain. You can fill air into the space overlapped by the LAG box or dam perhaps (?). If I may suggest, please review my tutorial before attempting to model with ALE. It typically requires a class to get going. Please find my old tutorial at:nhttp:/ftp.lstc.com/anonymous/outgoing/ian/aletutorial.tar.gzn
    • patjoy
      Subscriber
      nThank you for the response, what I was trying to do was replicate this example (bore in a box simulation) using the *MAT_ALE_INCOMPRESSIBLE material and the S-ALE solver but I have failed every time I try:nhttps://www.dynaexamples.com/ale/intermediate-example/wavestructurenIf I understand your tutorial properly then if I want to use the *MAT_ALE_INCOMPRESSIBLE to model the water then I need to use ELFORM=12 and not actually model the air but instead replace where I had air with *INITIAL_VOID_PART and the part properties for the void part must be the same as for the *MAT_ALE_INCOMPRESSIBLE part. I am pretty sure that my next problem for why my model fails to run is I am not sure how to define the *INITIAL_VOLUME_FRACTION_GEOMETRY card as these require a AMMGID which can't be used with *INITIAL_VOID_PART (according to the manuals). The manual states that when ELFORM=12 the non-void material defaults to AMMG=1 and the void to AMMG=2 but then I am not to sure what BAMMG should be or FAMMG.nThe only reason I am looking into this *MAT card is because the S-ALE solver for my version of LS-DYNA doesn't support *EOS_MURNAGHAN and using *EOS_MIE_GRUNEISEN takes significantly longer to model and results in a fluid that does not model well documented fluid simulations properly (bore in a box).nn
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