Learning Forum

[javat33489]

Hi all.

I also simulate rock drilling using SPH particles.

I use the increased density to speed up the solution to the problem. Increasing the density for SPH is not recommended, but I did such tests, I also do tests without increasing the density, they have not yet completed. But I have questions.

The task is similar to LSTC

https://www.lstc-cmmg.org/drilling

Only I use the rock and my feed and drilling speeds. I use an average speed of 25 m/s feed speed and 27 rad/s drilling speed. While solving the problem, I encountered several problems. 

1. Particles scatter wildly. And when the particles fly apart, they pull the solid ring behind them and it is greatly distorted:

2.I reduced the density a little, the solution became better and I got good stress. I also replaced the EROSION contact with AUTOMATIC:

But the particles still fly away strongly and do not break off in large pieces. Why? how to deal with this? It happens like this: the drill pierces the particles, they begin to fly away more and more until the end of the calculation time.

I use concrete material JHC

[javat33489]

Hi all. I reduced the density back to the original and also did the calculation with the density increased by only 1e2. In this case, solutions with density without increase and increased density do not differ. This makes me happy, it means I can use the option with increased density. BUT I am very concerned about the strong scattering of particles:

 

increased density

 

original density

[javat33489]

Perhaps the problem is in the extremely low selected limit stresses/pressures, but I checked the material, it is set correctly.

Perhaps the whole point is in the viscosity of the SPH, then what can be done:

1.SECTION SPH card in stock, change parameters there

2.Artificially increase viscosity

3.Play with the *CONTROL_BULK_VISCOSITY card, perhaps

4. We use KHORUGLAS for this part, the map is in stock, try to play with it, most likely it is completely unnecessary in this case for geomechanics.

No more thoughts yet. I need your advice. Thank you.

[javat33489]

What do you say colleagues?

[javat33489]

I need your professional help please

[javat33489]

HELP PLEASE

[javat33489]

Fine. I was trying to increase the viscosity and played with the HOURGLASS card for concrete. But it did not help.

[javat33489]

I found the reason why the particles fly apart. It's all about the JHC material model. When this model is used, the particles fly apart. When I used MOHR-COULOMB, the particles began to behave more physically