Regarding the implementation of erosion criteria in SPH formulations

[Nikesh Kumar Ojha]

Hello all,

I am currently simulating an impact problem using LS-DYNA, where I have employed the SPH technique. I would like to implement an erosion criterion for SPH particles and have the following doubts:

1. Can erosion criteria be applied in the SPH method? If yes,

2. How can different erosion criteria (such as pressure-based or temperature-based) be implemented?

I would greatly appreciate your suggestions in this regard

Regards

nikesh

[l...@schwer.net]

1\ I believe erosion is available for SPH particles.

 

2\ The key word *MAT_ADD_EROSION offers many forms of built in erosion criteria. In particular

 

MXPRES -- Maximum pressure at failure, Pmax. If the value is exactly zero, it is automatically excluded to maintain compatibility with old input

files.

 

See the User Manual Volume II

 

I do not believe there is a temperature based erosion criterion.

 

                                --len

--
You received this message because you are subscribed to the Google Groups "LS-DYNA2" group.
To unsubscribe from this group and stop receiving emails from it, send an email to ls-dyna2+u...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/ls-dyna2/f7982b6d-a185-418f-8d1d-369ca2a4ce31n%40googlegroups.com.

[Emin Akca]

Hi,

Yes, as Len answered, erosion is available for SPH particles. You can use *MAT_ADD_EROSION comfortably.

You should specify IEROD and ISHOW parameters in the Opt1 card of *CONTROL_SPH. The distinction is SPH particles will not be deleted from LSPP GUI when they are eroded; instead, they will be deactivated. However, you cannot distinguish the deactivated SPH particles with the standard appearance, you should use 'smooth' view. For this, please go to Model → Appear and make SPHstyle 'Smooth' instead of the default 'Point' style. Then, the active particles keep appearing in 'Smooth' style whereas the deactivated particles appear as simple black dots in GUI. 

• IEROD:=Deactivation control for SPH particles:
  EQ.0: Particles remain active.
  EQ.1: SPH particles are deactivated and stress states are set to 0 when erosion criteria are satisfied.
  EQ.2: SPH particles are totally deactivated and stress states are set to 0 when erosion criteria are satisfied.  See the 3rd remark in the manual.
  EQ.3: SPH particles are totally deactivated and stress states are set to 0 when erosion criteria are satisfied If an EOS is defined, the volumetric response is unaffected. See the 3rd remark in the manual.
  
  
• ISHOW:  Display option for deactivated SPH particles:
  EQ.0: No distinction in active SPH particles and deactivated SPH particles when viewing in LS-PrePost.
  EQ.1: Deactivated SPH particles are displayed only as points and active SPH particles are displayed as spheres when Setting → SPH → Style is set to “smooth” in LS-PrePost.

Best,

–Emin