Explosive leakage issue in Rock Blasting

[Ezio Antonio]

Dear all,

I’m trying to reproduce/validate the blast simulation from Xie et al. (2017) (Paper attached)

I’m running a 2D plane strain model of a cylindrical rock specimen with a 6.45 mm central hole. As in the paper, a copper tube/liner is placed between the explosive and the rock.

Model setup

• Lagrangian: rock (MAT_RHT), copper (MAT_JOHNSON_COOK)

• ALE: explosive (MAT_HIGH_EXPLOSIVE_BURN), polyethylene + water (MAT_NULL), and vacuum/air

• Coupling: CONSTRAINED_LAGRANGE_IN_SOLID

To improve the interaction between the ALE materials inside the hole and the copper liner, I introduced a small vacuum gap between the ALE region and the copper.

Issue
After detonation, I observe explosive products leaking into the vacuum gap and, because that vacuum region overlaps the rock in places, it appears that the ALE material intrudes into the rock domain.

Attached

1. Geometry/parts figure

2. CLIS setup (IN_SOLID card + part IDs)

3. GIF showing the leakage

4. The referenced paper (Xie et al., 2017)

Any suggestions on solving this leakage (e.g., CLIS definition, gap treatment, ALE mesh/volume fractions, interface/contact strategy) would be greatly appreciated.

Best regards,

Ezio

[l...@schwer.net]

1\ Not included were

1.            Geometry/parts figure

2.            CLIS setup (IN_SOLID card + part IDs)

 

2\ Based on the animated GIF, you seem to have some mesh bias, i.e. the leakage occurs more in one area rather than symmetrically.

 

3\ Why replace air (experiment) by vacuum?

 

4\ I think this problem might be better modeled using *SECTION_ALE2D with ELFORM=14, e.g. a series of 2D shell elements along the x-axis with the y-direction constrained for plane strain.

 

5\ I am not sure how well CLIS will work in this mesh configuration?

 

Note: you will need a minimum of 10 Eulerian cells across the radius of the explosive.

 

                --len

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[Masoud Sdg]

Hi Len,

Thanks for the helpful notes.

It looks like the parts figure and CLIS setup didn’t upload properly. Sorry about that. I’m attaching them here. They should also clarify the meshing; I agree the leakage is non-symmetric, so mesh bias could be contributing.

On vacuum vs air: I used vacuum to avoid adding resistance/pressure in the gap, but I’m not sure it’s the right choice. I can switch to a low-density air model to match the experiment.

I used ELFORM=13 since my next step is a non-symmetric configuration, but I can also try SECTION_ALE2D (ELFORM=14) for this validation if you think it’s more robust.

Finally, if CLIS isn’t suitable for this setup, what would you recommend instead for ALE–Lagrange interaction?

Best regards,
Ezio

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