Meshing a Mid-Surfaced Bracket for a Structural Analysis

Summary: This example illustrates how to use topology based connection to generate conformal surface mesh.

Objective

To create conformal surface mesh,you can scaffold topofaces, topoedges or both to connect all the surface bodies and mesh the bracket with quad elements.

Procedure

• Launch Ansys Prime Server

• Import CAD geometry and create part per CAD model

• Scaffold topofaces and topoedges with tolerance parameter

• Surface mesh topofaces with constant size and generate quad elements

• Write a cdb file for use in the APDL solver

• Exit the PyPrimeMesh session

Launch Ansys Prime Server

. Import all necessary modules.

# . Launch an instance of Ansys Prime Server.

# . Connect PyPrimeMesh client and get the model.

import os
import tempfile

from ansys.meshing import prime
from ansys.meshing.prime.graphics import Graphics

prime_client = prime.launch_prime()
model = prime_client.model

Import CAD geometry

. Download the bracket geometry file(.fmd file exported by SpaceClaim).

# . Import CAD geometry.

# . Create part per CAD model for topology based connection.

bracket_file = prime.examples.download_bracket_fmd()

file_io = prime.FileIO(model)
file_io.import_cad(
    file_name=bracket_file,
    params=prime.ImportCadParams(
        model=model,
        length_unit=prime.LengthUnit.MM,
        part_creation_type=prime.PartCreationType.MODEL,
    ),
)

<ansys.meshing.prime.autogen.fileiostructs.ImportCadResults object at 0x7fc9350b62f0>

Review the part

. Get the part summary.

# . Display the model to show edges by connection.

# . Use keyboard shortcuts to switch between
# surface (s) and wireframe (w) representation.

# . Colour code for edge connectivity -
# Red: free; Black: double; Purple: triple.

part = model.get_part_by_name('bracket_mid_surface-3')
part_summary_res = part.get_summary(prime.PartSummaryParams(model, print_mesh=False))
print(part_summary_res)

display = Graphics(model=model)
display()

message :
Part Name: bracket_mid_surface-3
Part ID: 2
    67 Topo Edges
    9 Topo Faces
    0 Topo Volumes

    0 Edge Zones
        Edge Zone Name(s) : []
    5 Face Zones
        Face Zone Name(s) : [midsurface1.1, midsurface2, midsurface3, midsurface4, midsurface1.2]
    0 Volume Zones
        Volume Zone Name(s) : []

    3 Label(s)
        Names: [back, hole_d14, hole_d20]

    Bounding box (1 1 0)
                 (20 30 30)
n_topo_edges :  67
n_topo_faces :  9
n_topo_volumes :  0
n_edge_zonelets :  0
n_face_zonelets :  0
n_cell_zonelets :  0
n_edge_zones :  0
n_face_zones :  5
n_volume_zones :  0
n_labels :  3
n_nodes :  0
n_faces :  0
n_cells :  0
n_tri_faces :  0
n_poly_faces :  0
n_quad_faces :  0
n_tet_cells :  0
n_pyra_cells :  0
n_prism_cells :  0
n_poly_cells :  0
n_hex_cells :  0
n_unmeshed_topo_faces :  0

Connection

. Initialize connection tolerance (which is smaller than target element size) and other parameters.

# . Scaffold topofaces, topoedges or both with connection parameters.

# target element size
element_size = 0.5

params = prime.ScaffolderParams(
    model,
    absolute_dist_tol=0.1 * element_size,
    intersection_control_mask=prime.IntersectionMask.FACEFACEANDEDGEEDGE,
    constant_mesh_size=element_size,
)

# Get existing topoface or topoedge ids
faces = part.get_topo_faces()
beams = []

scaffold_res = prime.Scaffolder(model, part.id).scaffold_topo_faces_and_beams(
    topo_faces=faces, topo_beams=beams, params=params
)
print(scaffold_res)

n_incomplete_topo_faces :  0
error_code :  ErrorCode.NOERROR

Surface mesh

. Initialize surface meshing parameters.

# . Mesh topofaces with constant size and generate quad elements.

surfer_params = prime.SurferParams(
    model=model,
    size_field_type=prime.SizeFieldType.CONSTANT,
    constant_size=element_size,
    generate_quads=True,
)

surfer_result = prime.Surfer(model).mesh_topo_faces(part.id, topo_faces=faces, params=surfer_params)

# Display the mesh
display = Graphics(model=model)
display()

Write mesh

Write a cdb file for use in the APDL solver.

with tempfile.TemporaryDirectory() as temp_folder:
    mapdl_cdb = os.path.join(temp_folder, 'bracket_scaffold.cdb')
    file_io.export_mapdl_cdb(mapdl_cdb, params=prime.ExportMapdlCdbParams(model))
    assert os.path.exists(mapdl_cdb)
    print(f'MAPDL case exported at {mapdl_cdb}')

MAPDL case exported at /tmp/tmpvibsnmp9/bracket_scaffold.cdb

Exit the PyPrimeMesh session

prime_client.exit()