Post-processing element erosion (projectile-plate impact)

This example post-processes element erosion in an LS-DYNA d3plot result of a tungsten-alloy projectile penetrating a steel plate, and plots the surviving mesh deformed by displacement at the final time step.

Both parts use *MAT_PLASTIC_KINEMATIC with a failure strain of 0.8, so elements are progressively deleted on impact. The simulation uses *CONTACT_ERODING_SURFACE_TO_SURFACE, which causes LS-DYNA to write a per-step element deletion flag to d3plot. DPF exposes that flag as the erosion_flag result (active = 1, eroded = 0). The workflow filters the active elements, extracts the corresponding sub-mesh, and visualizes the deformed geometry at the final time step (t ≈ 70 µs).

Note

This example requires DPF 8.0 (ansys-dpf-server-2024-R2) or above. For more information, see Compatibility.

from ansys.dpf import core as dpf
from ansys.dpf.core import examples

Load the LS-DYNA result file

The dataset contains 16 output states at roughly 5 µs intervals (units: gram, cm, microsecond). Each state is stored in a separate file (ieverp = 1), so all 17 paths returned by the download helper must be present in the same directory for DPF to read the full time history.

d3plot_paths = examples.download_d3plot_projectile()
ds = dpf.DataSources()
ds.set_result_file_path(filepath=d3plot_paths[0], key="d3plot")
my_model = dpf.Model(data_sources=ds)
print(my_model)

DPF Model
------------------------------
Unknown analysis
Unit system: Undefined
Physics Type: Unknown
Available results:
     -  global_kinetic_energy: TimeFreq_steps Global Kinetic Energy
     -  global_internal_energy: TimeFreq_steps Global Internal Energy
     -  global_total_energy: TimeFreq_steps Global Total Energy
     -  global_velocity: TimeFreq_steps Global Velocity
     -  initial_coordinates: Nodal Initial Coordinates
     -  coordinates: Nodal Coordinates
     -  velocity: Nodal Velocity
     -  acceleration: Nodal Acceleration
     -  stress: Elemental Stress
     -  stress_von_mises: Elemental Stress Von Mises
     -  plastic_strain_eqv: Elemental Plastic Strain Eqv
     -  erosion_flag: Elemental Erosion Flag
     -  displacement: Nodal Displacement
------------------------------
DPF  Meshed Region:
  7668 nodes
  5664 elements
  Unit:
  With solid (3D) elements
------------------------------
DPF  Time/Freq Support:
  Number of sets: 16
Cumulative     Frequency ()   LoadStep       Substep
1              0.000000       1              1
2              4.976857       2              1
3              9.953713       3              1
4              14.980842      4              1
5              19.957699      5              1
6              24.984827      6              1
7              29.961683      7              1
8              34.988811      8              1
9              39.965668      9              1
10             44.992794      10             1
11             49.969654      11             1
12             54.996780      12             1
13             59.973637      13             1
14             64.950493      14             1
15             69.977623      15             1
16             70.027893      16             1

Extract the erosion flag at the final time step

The erosion flag is an elemental result: active elements carry a value of 1, eroded elements carry a value of 0. State 16 corresponds to t ≈ 70 µs, when penetration is complete and erosion is most extensive.

last_step = my_model.metadata.time_freq_support.n_sets
erosion_fc = my_model.results.erosion_flag(time_scoping=[last_step]).eval()
print(erosion_fc)

DPF  Fields Container
  with 1 field(s)
  defined on labels: time

  with:
  - field 0 {time:  16} with Elemental location, 1 components and 5664 entities.

Isolate the non-eroded elements

Apply a high-pass filter to retain only elements whose flag exceeds 0.5, effectively selecting the active (non-eroded) elements.

active_fc = dpf.operators.filter.field_high_pass_fc(
    fields_container=erosion_fc, threshold=0.5
).eval()

# Retrieve the elemental scoping of the surviving elements
active_elemental_scoping = active_fc[0].scoping
print(active_elemental_scoping)

DPF  Scoping:
  with Elemental location and 5050 entities

Build the undeformed non-eroded sub-mesh

Extract the portion of the full mesh that corresponds to the active elements.

full_mesh = my_model.metadata.meshed_region
sub_mesh = dpf.operators.mesh.from_scoping(scoping=active_elemental_scoping, mesh=full_mesh).eval()
sub_mesh.plot(
    text="Undeformed mesh with erosion at the final time step",
    cpos=(1, -1, 1),
)

([], <pyvista.plotting.plotter.Plotter object at 0x00000215D94F3AD0>)

Rescope displacement to the non-eroded nodes

Transpose the elemental scoping to the equivalent nodal scoping, then extract the displacement and restrict it to the active nodes.

active_nodal_scoping = dpf.operators.scoping.transpose(
    mesh_scoping=active_elemental_scoping, meshed_region=full_mesh
).eval()

disp_fc = my_model.results.displacement(time_scoping=[last_step]).eval()
active_disp_fc = dpf.operators.scoping.rescope_fc(
    fields_container=disp_fc, mesh_scoping=active_nodal_scoping
).eval()

Plot the deformed non-eroded mesh

Displacement magnitude on the surviving mesh, deformed according to the displacement field. Eroded elements from both the projectile nose and the plate penetration zone are absent from the scene.

active_disp_fc[0].plot(
    meshed_region=sub_mesh,
    deform_by=active_disp_fc[0],
    text="Displacement at t ≈ 70 µs",
    cpos=(1, -1, 1),
)

(None, <pyvista.plotting.plotter.Plotter object at 0x00000215D9733250>)