Preparing the data for surface loads (case 1)

Load main libraries, set paths and adjust plotting theme (optional)

from pathlib import Path
import numpy as np
import pyvista as pv
pv.set_jupyter_backend('static')
pv.global_theme.background = 'white'
pv.global_theme.color = "beige"
pv.global_theme.show_edges = True
pv.global_theme.window_size = [800, 400]

STATICS_DIR = Path("../../../../_static")
HEXBEAM_MULTIBLOCK_FILEPATH = STATICS_DIR / "hexbeam_multiblock_surface_load_case_1.vtm"

Load the Mesh

In this examples, we are simply interested in manipulating the FEB file and not the mesh itself, therefore we will be used pre-defined mesh. If you wish to create the mesh using python, we recommend using the pyvista or the gmsh and pygmsh libraries.

mb = pv.read(HEXBEAM_MULTIBLOCK_FILEPATH)
mb

Information	Blocks
MultiBlock Values N Blocks 2 X Bounds -1.000, 1.000 Y Bounds -0.500, 0.500 Z Bounds 0.000, 1.000	Index Name Type 0 grid UnstructuredGrid 1 selected_load_surface UnstructuredGrid

Extract each block from the multiblock

grid = mb["grid"]
selected_load_surface = mb["selected_load_surface"]

Extract the field data (just to make it easier later on)

grid_boundary_ids = grid.field_data["boundary_ids"]
load_surface_connectivity = selected_load_surface.field_data["load_surface_connectivity"]

Plot data

plotter = pv.Plotter()
plotter.add_mesh(grid, color="beige", opacity=0.5)
plotter.add_points(grid.points[grid_boundary_ids], color="red", point_size=6)
plotter.add_mesh(selected_load_surface, color="blue", point_size=6)
plotter.show()

Create FEB

Create a FEB object:

from febio_python import Feb

feb = Feb(version=2.5)

Setup basic configurations:

feb.setup_module(module_type="solid") # default values
feb.setup_globals(T=0, R=0, Fc=0) # default values
feb.setup_controls(analysis_type="static") # here, you can change basic settings. See docs for more info.
feb.setup_output(variables=["displacement", "Lagrange strain", "stress"]) # default values

Add materials

from febio_python.core import Material

# Define the material
material_1 = Material(
    id=1,
    type="isotropic elastic",
    name="FirstBlockMaterial",
    parameters=dict(
        E=2e3,
        v=0.3,
        density=1,
    )
)

Add the material to the FEB object

feb.add_materials([material_1])

Add mesh

from febio_python.core import Nodes, Elements

# Define the nodes
grid_nodes = Nodes(name="FirstBlockNodes", coordinates=grid.points)

# Define the elements
grid_elements = Elements(
    name="FirstBlockElements",
    type="HEXAHEDRON",
    connectivity=grid.cells_dict[pv.CellType.HEXAHEDRON],
    mat=1
)

Add the nodes and elements to the FEB object

feb.add_nodes([grid_nodes])
feb.add_elements([grid_elements])

Add Nodesets

from febio_python.core import NodeSet

# Define the node sets
boundary_nodeset = NodeSet(
    name="BoundaryNodes",
    ids=grid_boundary_ids
)

Add node sets to the FEB object

feb.add_node_sets([boundary_nodeset])

Add Boundary conditions

from febio_python.core import FixCondition
# create the fixed boundary condition
fixed = FixCondition(
    dof="x,y,z",  # fix only the z direction
    node_set="BoundaryNodes",
    name="Fixed")

Add the fixed boundary condition to the FEB object

feb.add_boundary_conditions([fixed])

Add Surfaces

from febio_python.core import Surfaces

# Define the surface
surface = Surfaces(
    name="LoadSurface",
    type="QUAD",
    connectivity=load_surface_connectivity,
)

Add surface to the FEB object

feb.add_surfaces([surface])

Add loads

from febio_python.core import SurfaceLoad, LoadCurve

# Define the surface load
load = SurfaceLoad(
        surface="LoadSurface",  # this is the surface name (must be in the FEB object)
        load_curve=1,  # this is the load curve ID
        name="SurfaceLoad",  # optional name
        scale=-1000, # scale factor
        linear=True,  # linear pressure load
        symmetric_stiffness=True)  # symmetric stiffness matrix

# Define the load curve
lc = LoadCurve(
    id=1,
    interpolate_type="linear",
    data=np.array([[0, 0], [1, 1]]))

Add load and load curve to the FEB object

feb.add_surface_loads([load])
feb.add_load_curves([lc])

Writing FEB

output_file = STATICS_DIR / "sample_surface_load_case_1_v25.feb"
feb.write(output_file)