John Reid pendulum example

This example is inspired by John Reid’s “Pendulum” example on the LS-DYNA Examples site. It shows how to use DYNA-Lib to create a keyword file for LS-DYNA and solve it within a Pythonic environment.

Perform required imports

Import required packages, including those for the keywords, deck, and solver.

import os
import pathlib
import shutil

import pandas as pd

from ansys.dyna.keywords import Deck
from ansys.dyna.keywords import keywords as kwd
from ansys.dyna.run import run_dyna

dynadir = "run"
dynafile = "pendulum.k"

p = pathlib.Path(dynadir)
p.mkdir(parents=True, exist_ok=True)

Create a deck and keywords

Create a deck, which is the container for all the keywords. Then, create and append individual keywords to the deck.

def write_deck(filepath):
    deck = Deck()

    # Append control keywords
    deck.extend(
        [
            kwd.ControlTermination(endtim=11.0),
            kwd.ControlEnergy(hgen=2, rwen=2),
            kwd.ControlOutput(npopt=1, neecho=3),
            kwd.ControlShell(istupd=1, theory=2),
        ]
    )

    # Append database keywords
    deck.extend(
        [
            kwd.DatabaseBinaryD3Plot(dt=1.00),
            kwd.DatabaseExtentBinary(ieverp=1),
            kwd.DatabaseBinaryD3Thdt(dt=999999),
            kwd.DatabaseGlstat(dt=0.10),
            kwd.DatabaseMatsum(dt=0.10),
            kwd.DatabaseNodout(dt=0.10),
            kwd.DatabaseHistoryNode(id1=350, id2=374, id3=678, id4=713),
            kwd.DatabaseRbdout(dt=0.10),
            kwd.DatabaseRcforc(dt=0.10),
        ]
    )

    # Define contacts
    deck.extend([kwd.ContactAutomaticSingleSurface(ssid=0, fs=0.08, fd=0.08), kwd.ControlContact(shlthk=2)])

    # Define gravity
    curve1 = kwd.DefineCurve(lcid=1)
    curve1.curves = pd.DataFrame({"a1": [0.00, 10000.00], "o1": [1.000, 1.000]})

    deck.extend([kwd.LoadBodyY(lcid=1, sf=0.00981), curve1])

    # Define boundary conditions

    # BoundarySpcNode edited needs to redo code gen
    BoundarySpcNode = kwd.BoundarySpcNode()
    BoundarySpcNode.nodes = pd.DataFrame(
        {
            "nid": [45004, 45005, 45010, 45011],
            "cid": [0, 0, 0, 0],
            "dofx": [1, 1, 1, 1],
            "dofy": [1, 1, 1, 1],
            "dofz": [1, 1, 1, 1],
            "dofrx": [0, 0, 0, 0],
            "dofry": [0, 0, 0, 0],
            "dofrz": [0, 0, 0, 0],
        }
    )

    deck.extend(
        [
            BoundarySpcNode,
            kwd.InitialVelocity(boxid=5, vx=0.0, vy=-12.0, vz=0.0),
            kwd.DefineBox(boxid=5, xmn=-120.0, xmx=-80.0, ymn=80.0, ymx=120.0, zmn=-30.0, zmx=30.0),
        ]
    )

    # Define parts and materials

    spherePart = kwd.Part()
    spherePart.parts = pd.DataFrame({"heading": ["sphere1", "sphere2"], "pid": [1, 2], "secid": [1, 2], "mid": [1, 1]})
    beamPart = kwd.Part()
    beamPart.parts = pd.DataFrame(
        {"heading": ["Pendulum Wires - Elastic Beams"], "pid": [45], "secid": [45], "mid": [45]}
    )

    deck.extend(
        [
            spherePart,
            # Aluminium
            kwd.MatPlasticKinematic(mid=1, ro=2.7e-6, e=68.9, pr=0.330, sigy=0.286, etan=0.00689),
            # Sections
            kwd.SectionShell(secid=1, elfrom=2, t1=1.0, t2=1.0, t3=1.0, t4=1.0),
            kwd.SectionShell(secid=2, elfrom=2, t1=1.0, t2=1.0, t3=1.0, t4=1.0),
            # Pendu Wires
            beamPart,
            kwd.SectionBeam(secid=45, elform=3, shrf=1.00000, qr_irid=1.0, a=10.0),
            kwd.MatElastic(mid=45, ro=7.86e-6, e=210.0, pr=0.30),
        ]
    )

    # Define deformable switching
    deck.extend([kwd.DeformableToRigid(pid=1), kwd.DeformableToRigid(pid=2)])

    # Define nodes and elements
    deck.extend([kwd.Include(filename="nodes.k")])

    deck.export_file(filepath)
    return deck


def run_post(filepath):
    pass


deck = write_deck(os.path.join(dynadir, dynafile))
shutil.copy("nodes.k", "run/nodes.k")

'run/nodes.k'

View the model

You can use the PyVista plot method in the deck class to view the model.

out = deck.plot(cwd=dynadir)

Run the Dyna solver

filepath = run_dyna(dynafile, working_directory=dynadir)
run_post(filepath)