Note
Go to the end to download the full example code.
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#
Perform required imports.
import os
import sys
from ansys.dyna.core.pre import examples, launch_dynapre
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
referring 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 MatFabric, MatRigid
from ansys.dyna.core.pre.dynamech import (
Airbag,
Contact,
ContactCategory,
ContactSurface,
Curve,
DynaMech,
PartSet,
Point,
RigidwallPlanar,
ShellFormulation,
ShellPart,
)
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.
2024-11-20 15:20:21 : Connected to kwServer...
2024-11-20 15:20:21 : /opt/hostedtoolcache/Python/3.10.15/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)
2024-11-20 15:20:21 : 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)
2024-11-20 15:20:21 : 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 constraints 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)
2024-11-20 15:20:21 : Material RIGID Created...
2024-11-20 15:20:21 : Material RIGID Created...
2024-11-20 15:20:21 : 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()
2024-11-20 15:20:21 : Output Setting...
2024-11-20 15:20:21 : DB Binary Created...
2024-11-20 15:20:21 : Control Accuracy Created...
2024-11-20 15:20:21 : Control Bulk Viscosity Created...
2024-11-20 15:20:21 : Control Energy Created...
2024-11-20 15:20:21 : Control Hourglass Created...
2024-11-20 15:20:21 : Control Shell Created...
2024-11-20 15:20:21 : Control Contact Created...
2024-11-20 15:20:21 : Contact Created...
2024-11-20 15:20:21 : Airbag Model Created...
2024-11-20 15:20:21 : Rigidwall Planar Created...
2024-11-20 15:20:21 : airbag_deploy.k is outputed...
'/server/output'
Total running time of the script: (0 minutes 0.109 seconds)