LS Dyna

LS Dyna

warnings in Explicit Dynamics

    • SONGYANG
      Subscriber

      Dear ANSYS community,

      Hi,

      I was doing a landing simulation using Explicit Dynamics, three warnings came out although the simulation had been finished. 

      1) There are bonded connection(s) where none of the Candidate nodes found a Target face. A node will be bonded to the closest face only and this may therefore result in non-bonded nodes. See log and prt file for more information.

      2) There are bonded connections that contain node(s) more than once as an actual bonded pair. A node will be bonded to the closest face only and this may therefore result in non-bonded parts. See log file for more information.

      3) Since the result file does not indicate the unit system, the following file Tunit system is assumed: Metric (mm, kg, N, s, mV, mA).

      In terms of warning 1, some researchers said the bonded connections should all be replaced by body interactions in Explicit Dynamics, is it right? I defined the contact surfaces between two bones as bonded connections in static structural, but how can I define a bonded condition between two bones using the body interactions? because only the bodies of bone can be selected for body interaction.

    • Ram Gopisetti
      Ansys Employee
      How about using shared topology replacing the all bonded contacts, Moreover, check the contacts are formed with proper offsets. Moreover, body interactions are mostly used for frictional or frictionless type.
      Cheeers, Ram
    • Chris Quan
      Ansys Employee
      The warning message #1 tells you that the contact node and target face are not bonded. You need to increase the Offset of the bonded contact to make them bonded.
      To verify the bond status, you need to run your model for 100 cycles and then create user-defined results - Bond_Status to check it. The faces having Bond_Status greater than0 are bonded.
      The warning message #2 tells you that a single contact node may be bonded to multiple target faces. This is OK but you need to check your model to make sure the faces in bonded contacts are selected correctly.


    • SONGYANG
      Subscriber
      Hi I used the default maximum offset of the bonded contact, could you give me some suggestions on increasing the offset? Thank you.
      The OFFSET value should be sufficient larger than the distance between contact nodes and target faces.
    • SONGYANG
      Subscriber
      @ram_gopisetti, Hi, thank you, could you tell more about using shared topology replacing the all bonded contacts?
    • Chris Quan
      Ansys Employee
      The OFFSET value should be sufficient larger than the distance between contact nodes and target faces.
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