How do I calculate element face normal of a solid element?

Ayush Kumar

How do I calculate element face (skin - outer element) normal of a solid element?

Ayush Kumar

For 22R2 and above:

import mech_dpf 
import Ans.DataProcessing as dpf

analysis = Model.Analyses[0]
model = dpf.DataSources(analysis.ResultFileName)

# Element ID for which you want a element face normal
element_id = 1596

# Get Mesh
op = dpf.operators.mesh.mesh_provider() # operator instanciation
op.inputs.data_sources.Connect(model)
my_mesh = op.outputs.mesh.GetData()

nodal_scoping = dpf.Scoping(Location="Nodal")
nodal_scoping.Ids = my_mesh.ElementById(element_id).NodeIds

# Extract Skin mesh from solid mesh
skin_mesh = dpf.operators.mesh.skin(mesh=my_mesh)
skin_mesh.inputs.mesh_scoping.Connect(nodal_scoping)
skin_meshed_region = skin_mesh.outputs.mesh.GetData()

# Get corresponding skin mesh element(s)
element_scoping = dpf.Scoping(Location="Elemental")
solid_element_index = my_mesh.ElementIds.IndexOf(element_id)

# Calculate normal to the element face
normal = dpf.operators.geo.normals_provider_nl()
normal.inputs.mesh.Connect(skin_meshed_region)
normal_vec_out_field = normal.outputs.field.GetData()

# Get all normal vectors to the element face(s)
skin_element_ids = skin_meshed_region.ElementScoping.Ids
normal_vectors = [normal_vec_out_field.GetEntityDataById(skin_element) for skin_element in skin_element_ids]

for 2021R2:

import mech_dpf 
import Ans.DataProcessing as dpf

analysis = Model.Analyses[0]
model = dpf.DataSources(analysis.ResultFileName)

# Element ID for which you want a element face normal
element_id = 1596

# Get Mesh
op = dpf.operators.mesh.mesh_provider() # operator instanciation
op.inputs.data_sources.Connect(model)
my_mesh = op.outputs.mesh.GetData()

# Extract Skin mesh from solid mesh
skin_mesh = dpf.operators.mesh.skin(mesh=my_mesh)
skin_meshed_region = skin_mesh.outputs.mesh.GetData()

"""
Skin mesh to solid mesh mapper.
This is needed becauses DPF creates new element IDs for skin mesh.

The location of solid element and corresponding skin mesh element is same,
therefore a mapper based on the location.
"""
skin_mesh_mapper = skin_mesh.outputs.property_field_new_elements_to_old.GetData()

# Get corresponding skin mesh element(s)
element_scoping = dpf.Scoping(Location="Elemental")
solid_element_index = my_mesh.ElementIds.IndexOf(element_id)

indexes = []
for index in range(len(skin_mesh_mapper.Data)):
    if skin_mesh_mapper.Data[index] == solid_element_index:
        indexes.append(index)

element_scoping.Ids = [skin_mesh_mapper.Scoping.Ids[index] for index in indexes]

# Calculate normal to the element face
normal = dpf.operators.geo.normals_provider_nl()
normal.inputs.mesh.Connect(skin_meshed_region)
normal.inputs.mesh_scoping.Connect(element_scoping)
normal_vec_out_field = normal.outputs.field.GetData()

# Get all normal vectors to the element face(s)
normal_vectors = [normal_vec_out_field.GetEntityDataById(skin_element) for skin_element in element_scoping.Ids]