Meshing a mid-surfaced bracket for a structural analysis

Summary: This example demonstrates 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 the CAD geometry and create the part per the CAD model.

• Scaffold topofaces and topoedges with a tolerance parameter.

• Surface mesh topofaces with a 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 the 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 (FMD) file exported by SpaceClaim. Import the CAD geometry. Create the part per the CAD model for the topology-based connection.

# For Windows OS users, scdoc is also available:
# bracket_file = prime.examples.download_bracket_scdoc()

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 0x7f3936404e20>

Review the part

Get the part summary. Display the model to show edges by connection. Use keyboard shortcuts to switch between the surface (s) and wireframe (w) representations. Color 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 the connection tolerance and other parameters. (The connection tolerance is smaller than the target element size.) Scaffold the 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 the 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/tmp90cuh876/bracket_scaffold.cdb

Exit the PyPrimeMesh session

prime_client.exit()