Airbag deploy

This example shows how to create an airbag deploy model with the PyDNYA pre service. The executable file for LS-DYNA is ls-dyna_smp_d_R13.0_365-gf8a97bda2a_winx64_ifort190.exe.

Perform required imports

Peform required imports.

import os
import sys


from ansys.dyna.core.pre import launch_dynapre
from ansys.dyna.core.pre.dynamech import (
    DynaMech,
    Airbag,
    PartSet,
    Curve,
    Point,
    RigidwallPlanar,
    Contact,
    ContactSurface,
    ContactCategory,
    ShellPart,
    ShellFormulation,
)

Start the pre service

Before starting the pre service, you must ensure that the Docker container for this service has been started. For more information, see “Start the Docker container for the pre service” in https://dyna.docs.pyansys.com/version/stable/index.html.

The pre service can also be started locally, please download the latest version of ansys-pydyna-pre-server.zip package from ansys/pydyna and start it refering to the README.rst file in this server package.

Once the pre service is running, you can connect a client to it using the hostname and port. This example uses the default localhost and port ("localhost" and "50051" respectively).

from ansys.dyna.core.pre.dynamaterial import MatRigid, MatFabric
from ansys.dyna.core.pre import examples
from ansys.dyna.core.pre.misc import check_valid_ip

hostname = "localhost"
if len(sys.argv) > 1 and check_valid_ip(sys.argv[1]):
    hostname = sys.argv[1]

Start the solution workflow

The DynaSolution class is like a workflow orchestrator. It inherits methods from other classes and helps create a complete workflow.

airbag_solution = launch_dynapre(ip = hostname)
fns = []
# path = sys.path[0] + os.sep + "input" + os.sep + "airbag_deploy" + os.sep
path = examples.airbag_deploy + os.sep
fns.append(path + "airbag_deploy.k")
airbag_solution.open_files(fns)

2024-04-01 01:27:37 :  Connected to kwServer...
2024-04-01 01:27:37 :  /opt/hostedtoolcache/Python/3.10.14/x64/lib/python3.10/site-packages/ansys/dyna/core/pre/examples/airbag/airbag_deploy/airbag_deploy.k uploaded to server...

ret: true

Create standard explicit control cards

The following code uses the set_termination method to set the termination time to 0.03 in CONTROL_TERMINATION. The DynaMech class automatically generates the common control cards used in explicit problems. CONTROL_ACCURACY, CONTACT, BULK VISCOCITY, and CONTACT are all automatically generated.

airbag_solution.set_termination(0.03)

airbagdeploy = DynaMech()
airbag_solution.add(airbagdeploy)

2024-04-01 01:27:37 :  Setting termination time ...

Define a keyword

Use the Airbag function in the DynaMech class to define AIRBAG_SIMPLE_AIRBAG_MODEL as a keyword. While LS-DYNA has many different airbag models, PyDYNA currently supports only one: SIMPLE_AIRBAG_MODEL. If you have an urgent need for PyDYNA to support another airbag model, email pyansys.core@ansys.com with your request.

airbag = Airbag(
    set=PartSet([3]),
    heat_capacity_at_constant_volume=1.736e3,
    heat_capacity_at_constant_pressure=2.43e3,
    input_gas_temperature=1.2e3,
    input_mass_flow_rate=Curve(x=[0, 0.032, 0.045, 0.08], y=[0, 26, 0.6, 0.1]),
    shape_factor_for_exit_hole=0.7,
    ambient_pressure=14.7,
    ambient_density=3.821e-6,
)
airbagdeploy.add(airbag)

2024-04-01 01:27:37 :  Curve 1 defined...

Generate an infinite planar rigid wall

To generate an infinite planar rigidwall, define the coordinates of the heat vector and the tail vector of the plane.

rigidwall = RigidwallPlanar(Point(0, 0, 0), Point(0, 1, 0), coulomb_friction_coefficient=0.5)
airbagdeploy.add(rigidwall)

Define a node-to-surface contact

Define a node-to-surface contact by passing a master part set and a slave part set.

contact = Contact(category=ContactCategory.NODES_TO_SURFACE)
contact.set_friction_coefficient(static=0.5, dynamic=0.5)
surf1 = ContactSurface(PartSet([3]))
surf2 = ContactSurface(PartSet([2]))
surf2.set_penalty_stiffness_scale_factor(0.06667)
contact.set_slave_surface(surf1)
contact.set_master_surface(surf2)
airbagdeploy.contacts.add(contact)

Define material cards

LS-DYNA has over 300 materials that are used for varied applications. While PyDYNA does not yet support all material cards, it does support most commonly used materials, including FABRIC, MAT_ELASTIC, PIECEWISE_LINEAR_PLASTICITY, and RIGID. All supported materials are accessed from the dynamaterial class. In the following code, MAT_RIGID is defined as the material for the cylindrical tube and the bottom plate. MAT_FABRIC is defined as the material for the airbag volume. Note that platemat also has contraints defined.

platemat = MatRigid(
    mass_density=7.84e-4,
    young_modulus=30e6,
    center_of_mass_constraint=1,
    translational_constraint=7,
    rotational_constraint=7,
)
cylindermat = MatRigid(mass_density=1.96e-4, young_modulus=30e6)
airbagmat = MatFabric(
    mass_density=1e-4,
    young_modulus_longitudinal_direction=2e6,
    young_modulus_transverse_direction=2e6,
    shear_modulus=1.53e6,
)

Define sectional properties

The following code defines the sectional properties of the parts. This example has three shell parts. Each shell part is initialized as ShellPart with a unique ID and an appropriate shell formulation is assigned. Again, PyDYNA does not yet support all element formulations. You can find the supported formulations in the dynabase class.

plate = ShellPart(1)
plate.set_material(platemat)
plate.set_element_formulation(ShellFormulation.BELYTSCHKO_TSAY)
plate.set_thickness(0.5)
airbagdeploy.parts.add(plate)

cylinder = ShellPart(2)
cylinder.set_material(cylindermat)
cylinder.set_element_formulation(ShellFormulation.BELYTSCHKO_TSAY)
cylinder.set_thickness(0.5)
airbagdeploy.parts.add(cylinder)

airbagpart = ShellPart(3)
airbagpart.set_material(airbagmat)
airbagpart.set_element_formulation(ShellFormulation.FULLY_INTEGRATED_BELYTSCHKO_TSAY_MEMBRANE)
airbagpart.set_thickness(0.015)
airbagpart.set_integration_points(4)
airbagdeploy.parts.add(airbagpart)

2024-04-01 01:27:37 :  Material RIGID Created...
2024-04-01 01:27:37 :  Material RIGID Created...
2024-04-01 01:27:37 :  Material Fabric Created...

Define database outputs

Use the set_output_database() and create_database_binary() methods to define the output frequency of the ASCII and binary D3PLOT files. Then, use the save_file() method to write out the model as an input DYNA key file.

airbag_solution.set_output_database(
    abstat=2.0e-4, glstat=2.0e-4, matsum=2.0e-4, rcforc=2.0e-4, rbdout=2.0e-4, rwforc=2.0e-4
)
airbag_solution.create_database_binary(dt=5e-4, ieverp=1)
airbag_solution.save_file()

2024-04-01 01:27:37 :  Output Setting...
2024-04-01 01:27:37 :  DB Binary Created...
2024-04-01 01:27:37 :  Control Accuracy Created...
2024-04-01 01:27:37 :  Control Bulk Viscosity Created...
2024-04-01 01:27:37 :  Control Energy Created...
2024-04-01 01:27:37 :  Control Hourglass Created...
2024-04-01 01:27:37 :  Control Shell Created...
2024-04-01 01:27:37 :  Control Contact Created...
2024-04-01 01:27:37 :  Contact  Created...
2024-04-01 01:27:37 :  Airbag Model Created...
2024-04-01 01:27:37 :  Rigidwall Planar Created...
2024-04-01 01:27:37 :  airbag_deploy.k is outputed...

'/server/output'