Belted dummy

This example shows how to use the PyDYNA pre service to create a belted dummy model. The executable file for LS-DYNA is ls-dyna_smp_d_R13.0_365-gf8a97bda2a_winx64_ifort190.exe.

Perform required imports

Perform the required imports.

import os
import sys

from belted_dummy_data import (
    curvedata,
    dampingconst,
    elasticmats,
    extra_nodes,
    jointlist,
    lcidlist,
    motion_curve_x,
    motion_curve_y,
    motion_nodes,
    nlist,
    rigidmats,
    segments,
    shellsec,
    vector,
)

from ansys.dyna.core.pre import examples, launch_dynapre
from ansys.dyna.core.pre.dynamaterial import (
    MatDamperNonlinearViscous,
    MatDamperViscous,
    MatElastic,
    MatRigid,
    MatSpringNonlinearElastic,
)
from ansys.dyna.core.pre.dynamech import (
    DRO,
    Contact,
    ContactCategory,
    ContactSurface,
    Curve,
    DiscretePart,
    DynaMech,
    Gravity,
    GravityOption,
    Motion,
    NodeSet,
    SegmentSet,
    ShellFormulation,
    ShellPart,
    Velocity,
)
from ansys.dyna.core.pre.misc import check_valid_ip

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 host name and port. This example uses the default localhost and port ("localhost" and "50051" respectively).

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

Start the solution workflow

NODES and ELEMENTS are read in from the belted_dummy.k file. This file also has the PART defined in it, but the section and material fields are empty to begin with.

fns = []
path = examples.belted_dummy + os.sep
fns.append(path + "belted_dummy.k")
dummy_solution.open_files(fns)

ret: true

Create database and control cards

For the D3plots, set simulation termination time, simulation timestep, and output frequency. Use the set_init_velocity method in the dynamech class to initialize the velocity components in the desired direction.

dummy_solution.set_termination(termination_time=0.12)
dummy_solution.create_database_binary(dt=2.5e-3)

dummy = DynaMech()
dummy_solution.add(dummy)

dummy.set_timestep(tssfac=0.8)
dummy.set_init_velocity(Velocity(14.8, 0, 0))

Define materials

In this model, many parts share common material types. Thus, these materials are generated in a loop and a list of these materials are created. This list can then be used later to assign materials to parts. The dynamaterials class are used to define these materials: MAT_RIGID, MAT_ELASTIC, MAT_SPRING_NONLINEAR_ELASTIC, MAT_DAMPER_VISCOUS, and MAT_DAMPER_NONLINEAR_VISCOUS.

shellmatlist = []
for i in range(15):
    matrigid = MatRigid(mass_density=rigidmats[i][0], young_modulus=rigidmats[i][1], poisson_ratio=0.3)
    shellmatlist.append(matrigid)

for i in range(16, 23):
    index = i - 16
    matelastic = MatElastic(mass_density=elasticmats[index][0], young_modulus=elasticmats[index][1], poisson_ratio=0.3)
    shellmatlist.append(matelastic)

discmatlist = []
for i in range(101, 143):
    index = i - 101
    mat = MatSpringNonlinearElastic(curve=Curve(x=curvedata[index][0], y=curvedata[index][1]))
    discmatlist.append(mat)

for i in range(143, 185):
    index = i - 143
    mat = MatDamperViscous(damping_constant=dampingconst[index])
    discmatlist.append(mat)

for i in range(185, 209):
    index = i - 185
    mat = MatDamperNonlinearViscous(curve=Curve(x=curvedata[lcidlist[index]][0], y=curvedata[lcidlist[index]][1]))
    discmatlist.append(mat)

Define section properties and assign materials

Now that you have a list of materials with the material ID corresponding to the part ID, you can loop through the list and assign these materials to the parts. While in the loop, also define the section properties, element formulations, and constraints.

for i in range(1, 23):
    part = ShellPart(i)
    part.set_element_formulation(ShellFormulation.BELYTSCHKO_TSAY)
    part.set_material(shellmatlist[i - 1])
    part.set_thickness(shellsec[i - 1][0])
    part.set_integration_points(shellsec[i - 1][1])
    if i in range(1, 16):
        part.set_extra_nodes(NodeSet(extra_nodes[i - 1]))
    dummy.parts.add(part)

for i in range(101, 209):
    index = i - 101
    part = DiscretePart(i)
    part.set_material(discmatlist[index])
    part.set_displacement_option(displacement_option=DRO.DESCRIBES_TORSIONAL_SPRING)
    dummy.parts.add(part)

Define surface-to-surface contacts

Define several surface-to-surface contacts between predefined segment set pairs such that each contact has a specific friction defined between the master and slave.

fslist = [0.62, 0.62, 0.62, 0.8, 1, 0.8, 0.88, 0.88, 0.16, 0.88, 0]
for i in range(11):
    contact = Contact(category=ContactCategory.SURFACE_TO_SURFACE_CONTACT)
    contact.set_friction_coefficient(static=fslist[i])
    surf1 = ContactSurface(SegmentSet(segments[2 * i]))
    surf2 = ContactSurface(SegmentSet(segments[2 * i + 1]))
    contact.set_slave_surface(surf1)
    contact.set_master_surface(surf2)
    dummy.contacts.add(contact)

Define spherical joints

A spherical joint is one of the simpler joint types. You need only define a coincident node pair. Read the node pairs from the jointlist array defined in the belted_dummy_data.py file.

for i in range(42):
    id = i + 1
    dummy.create_defineorientation(vid=id, iop=2, vector=vector, node1=nlist[i][0], node2=nlist[i][1])

for i in range(14):
    dummy.constraints.create_joint_spherical(nodes=jointlist[i])

Define a prescribed motion on a node set

Use the create_imposed_motion() method to define a prescribed motion on a node set.

dummy.boundaryconditions.create_imposed_motion(
    NodeSet(motion_nodes),
    Curve(x=motion_curve_x, y=motion_curve_y, sfo=0.1),
    motion=Motion.ACCELERATION,
    scalefactor=-1,
)

Define gravity

Use the Gravity() method in the dynabase class to define the gravity load, direction of the load, and the curve.

g = Gravity(dir=GravityOption.DIR_Z, load=Curve(x=[0, 0.152], y=[9.81, 9.81]))
dummy.add(g)

Define database outputs

Define the frequency for the D3PLOT file and write out the input file.

dummy_solution.create_database_binary(dt=2.5e-3)
dummy_solution.save_file()

'/server/output'