Note
Go to the end to download the full example code.
Buckling of beer can example#
This example is inspired by the “Buckling of Beer Can” example on the LS-DYNA Knowledge Base site. It shows how to use PyDyna to create a keyword file for LS-DYNA and then solve it from Python.
Perform required imports#
Import required packages, including those for the keywords, deck, and solver.
import os
import shutil
# subprocess is used to run LS-DYNA commands, excluding bandit warning
import subprocess # nosec: B404
import tempfile
import numpy as np
import pandas as pd
from ansys.dyna.core import Deck, keywords as kwd
from ansys.dyna.core.pre.examples.download_utilities import EXAMPLES_PATH, DownloadManager
from ansys.dyna.core.run import MemoryUnit, MpiOption, run_dyna
rundir = tempfile.TemporaryDirectory()
mesh_file_name = "mesh.k"
mesh_file = DownloadManager().download_file(
mesh_file_name, "ls-dyna", "Buckling_Beer_Can", destination=os.path.join(EXAMPLES_PATH, "Buckling_Beer_Can")
)
dynafile = "beer_can.k"
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
contact_auto = kwd.ContactAutomaticSingleSurfaceMortar(cid=1)
contact_auto.options["ID"].active = True
contact_auto.heading = "Single-Surface Mortar Contact (The New Explicit/Implicit Standard)"
deck.extend(
[
contact_auto,
kwd.ControlAccuracy(iacc=1),
kwd.ControlImplicitAuto(iauto=1, dtmax=0.01),
kwd.ControlImplicitDynamics(imass=1, gamma=0.6, beta=0.38),
kwd.ControlImplicitGeneral(imflag=1, dt0=0.01),
kwd.ControlImplicitSolution(nlprint=2),
kwd.ControlShell(esort=2, theory=-16, intgrd=1, nfail4=1, irquad=0),
kwd.ControlTermination(endtim=1.0),
]
)
# Append database keywords
deck.extend(
[
kwd.DatabaseGlstat(dt=1.0e-4, binary=3, ioopt=0),
kwd.DatabaseSpcforc(dt=1e-4, binary=3, ioopt=0),
kwd.DatabaseBinaryD3Plot(dt=1.0e-4),
kwd.DatabaseExtentBinary(maxint=-3, nintsld=1),
]
)
# Part keywords
can_part = kwd.Part(heading="Beer Can", pid=1, secid=1, mid=1, eosid=0)
floor_part = kwd.Part(heading="Floor", pid=2, secid=2, mid=1)
# Material keywords
mat_elastic = kwd.MatElastic(mid=1, ro=2.59e-4, e=1.0e7, pr=0.33, title="Aluminum")
mat_elastic.options["TITLE"].active = True
# Section keywords
can_shell = kwd.SectionShell(secid=1, elform=-16, shrf=0.8333, nip=3, t1=0.002, propt=0.0, title="Beer Can")
can_shell.options["TITLE"].active = True
floor_shell = kwd.SectionShell(secid=2, elform=-16, shrf=0.833, t1=0.01, propt=0.0)
floor_shell.options["TITLE"].active = True
floor_shell.title = "Floor - Just for Contact (Rigid Wall Would Have Worked Also)"
deck.extend(
[
can_part,
can_shell,
floor_part,
floor_shell,
mat_elastic,
]
)
# Load curve
load_curve = kwd.DefineCurve(lcid=1, curves=pd.DataFrame({"a1": [0.00, 1.00], "o1": [0.0, 1.000]}))
load_curve.options["TITLE"].active = True
load_curve.title = "Load vs. Time"
deck.append(load_curve)
# Define boundary conditions
load_nodes = [
50,
621,
670,
671,
672,
673,
674,
675,
676,
677,
678,
679,
680,
681,
682,
683,
684,
685,
686,
687,
31,
32,
33,
34,
35,
36,
37,
38,
39,
40,
41,
42,
43,
44,
45,
46,
47,
48,
49,
1229,
1230,
1231,
1232,
1233,
1234,
1235,
1236,
1237,
1238,
1239,
1240,
1241,
1242,
1243,
1244,
1245,
1246,
1247,
1799,
1800,
1801,
1802,
1803,
1804,
1805,
1806,
1807,
1808,
1809,
1810,
1811,
1812,
1813,
1814,
1815,
1816,
]
count = len(load_nodes)
zeros = np.zeros(count)
load_node_point = kwd.LoadNodePoint(
nodes=pd.DataFrame(
{
"nid": load_nodes,
"dof": np.full((count), 3),
"lcid": np.full((count), 1),
"sf": np.full((count), -13.1579),
"cid": zeros,
"m1": zeros,
"m2": zeros,
"m3": zeros,
}
)
)
deck.append(load_node_point)
nid = [
1,
31,
32,
33,
34,
35,
36,
37,
38,
39,
40,
41,
42,
43,
44,
45,
46,
47,
48,
49,
50,
80,
81,
82,
83,
84,
85,
86,
87,
88,
89,
90,
91,
92,
93,
94,
95,
96,
97,
98,
621,
651,
652,
653,
654,
655,
656,
657,
658,
659,
660,
661,
662,
663,
664,
665,
666,
667,
668,
669,
670,
671,
672,
673,
674,
675,
676,
677,
678,
679,
680,
681,
682,
683,
684,
685,
686,
687,
1210,
1211,
1212,
1213,
1214,
1215,
1216,
1217,
1218,
1219,
1220,
1221,
1222,
1223,
1224,
1225,
1226,
1227,
1228,
1229,
1230,
1231,
1232,
1233,
1234,
1235,
1236,
1237,
1238,
1239,
1240,
1241,
1242,
1243,
1244,
1245,
1246,
1247,
1799,
1800,
1801,
1802,
1803,
1804,
1805,
1806,
1807,
1808,
1809,
1810,
1811,
1812,
1813,
1814,
1815,
1816,
1817,
1818,
1819,
1820,
1821,
1822,
1823,
1824,
1825,
1826,
1827,
1828,
1829,
1830,
1831,
1832,
1833,
1834,
]
count = len(nid)
zeros = np.zeros(count)
ones = np.full((count), 1)
dofz = [
1,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
0,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
]
boundary_spc_node = kwd.BoundarySpcNode(
nodes=pd.DataFrame(
{
"nid": nid,
"cid": zeros,
"dofx": ones,
"dofy": ones,
"dofz": dofz,
"dofrx": ones,
"dofry": ones,
"dofrz": ones,
}
)
)
deck.append(boundary_spc_node)
# Define nodes and elements
deck.append(kwd.Include(filename=mesh_file_name))
deck.export_file(filepath)
return deck
def run_post(filepath):
pass
shutil.copy(mesh_file, os.path.join(rundir.name, mesh_file_name))
deck = write_deck(os.path.join(rundir.name, dynafile))
View the model#
You can use the PyVista plot method in the deck class to view
the model.
deck.plot(cwd=rundir.name)
Run the Dyna solver#
try:
run_dyna(
dynafile,
working_directory=rundir.name,
ncpu=2,
mpi_option=MpiOption.MPP_INTEL_MPI,
memory=20,
memory_unit=MemoryUnit.MB,
)
except subprocess.CalledProcessError:
# this example doesn't run to completion because it is a highly nonlinear buckling
pass
run_post(rundir.name)
License option : check ansys licenses only
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Date: 01/27/2026 Time: 14:40:25
___________________________________________________
| |
| LS-DYNA, A Program for Nonlinear Dynamic |
| Analysis of Structures in Three Dimensions |
| Date : 10/16/2023 Time: 19:29:09 |
| Version : mpp d R14 |
| Revision: R14.1-205-geb5348f751 |
| AnLicVer: 2024 R1 (20231025+2752148) |
| |
| Features enabled in this version: |
| Distributed Memory Parallel |
| CESE CHEMISTRY EM ICFD STOCHASTIC_PARTICLES |
| FFTW (multi-dimensional FFTW Library) |
| ANSYSLIC enabled |
| |
| Platform : Intel-MPI 2018 Xeon64 |
| OS Level : Linux CentOS 7.9 uum |
| Compiler : Intel Fortran Compiler 19.0 SSE2 |
| Hostname : 6c9a4250757f |
| Precision : Double precision (I8R8) |
| |
| Unauthorized use infringes Ansys Inc. copyrights |
|___________________________________________________|
[license/info] Successfully checked out 2 of "dyna_solver_core".
[license/info] --> Checkout ID: 6c9a4250757f-root-23-000004 (days left: 357)
[license/info] --> Customer ID: 0
[license/info] Successfully started "LSDYNA (Core-based License)".
Executing with ANSYS license
Command line options: i=beer_can.k
memory=20m
Input file: beer_can.k
The native file format : 64-bit small endian
Memory size from command line: 20000000, 0
Memory size from command line: 20000000, 20000000
Memory for the head node
Memory installed (MB) : 64301
Memory available (MB) : 61634
on UNIX computers note the following change:
ctrl-c interrupts ls-dyna and prompts for a sense switch.
type the desired sense switch: sw1., sw2., etc. to continue
the execution. ls-dyna will respond as explained in the users manual
type response
----- ------------------------------------------------------------
quit ls-dyna terminates.
stop ls-dyna terminates.
sw1. a restart file is written and ls-dyna terminates.
sw2. ls-dyna responds with time and cycle numbers.
sw3. a restart file is written and ls-dyna continues calculations.
sw4. a plot state is written and ls-dyna continues calculations.
sw5. ls-dyna enters interactive graphics phase.
swa. ls-dyna flushes all output i/o buffers.
swb. a dynain is written and ls-dyna continues calculations.
swc. a restart and dynain are written and ls-dyna continues calculations.
swd. a restart and dynain are written and ls-dyna terminates.
swe. stop dynamic relaxation just as though convergence
endtime=time change the termination time
lpri toggle implicit lin. alg. solver output on/off.
nlpr toggle implicit nonlinear solver output on/off.
iter toggle implicit output to d3iter database on/off.
prof output timing data to prof.out and continue.
conv force implicit nonlinear convergence for current time step.
ttrm terminate implicit time step, reduce time step, retry time step.
rtrm terminate implicit at end of current time step.
******** notice ******** notice ******** notice ********
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* This is the LS-DYNA Finite Element code. *
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* the validity, accuracy, or applicability of any results *
* obtained from this system. Users must verify their own *
* results. *
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* LST endeavors to make the LS-DYNA code as complete, *
* accurate and easy to use as possible. *
* Suggestions and comments are welcomed. Please report any *
* errors encountered in either the documentation or results *
* immediately to LST through your site focus. *
* *
* Copyright (C) 1990-2021 *
* by Livermore Software Technology, LLC *
* All rights reserved *
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******** notice ******** notice ******** notice ********
Beginning of keyword reader 01/27/26 14:40:35
01/27/26 14:40:35
Open include file: mesh.k
Memory required to process keyword : 285092
Additional dynamic memory required : 2394491
MPP execution with 2 procs
Initial reading of file 01/27/26 14:40:35
Implicit dynamics is now active
Performing Decomposition -- Phase 1 01/27/26 14:40:35
Performing Recursive Coordinate Bisection (RCB)
Memory required for decomposition : 53592
Additional dynamic memory required : 2559869
Performing Decomposition -- Phase 2 01/27/26 14:40:35
Performing Decomposition -- Phase 3 01/27/26 14:40:35
Implicit dynamics is now active
input of data is completed
initial kinetic energy = 0.00000000E+00
The LS-DYNA time step size should not exceed 1.656E-07
to avoid contact instabilities. If the step size is
bigger then scale the penalty of the offending surface.
Implicit dynamics is now active
termination time = 1.000E+00
The following binary output files are being created,
and contain data equivalent to the indicated ascii output files
binout0000: (on processor 0)
glstat
spcforc
Memory required to begin solution (memory= 320K)
Minimum 281K on processor 1
Maximum 320K on processor 0
Average 301K
Matrix Assembly dynamically allocated memory
Maximum 160K
Additional dynamically allocated memory
Minimum 4056K on processor 1
Maximum 4374K on processor 0
Average 4215K
Total allocated memory
Minimum 4496K on processor 1
Maximum 4854K on processor 0
Average 4675K
initialization completed
calculation with mass scaling for minimum dt
added mass = 0.0000E+00
physical mass= 6.5553E-05
ratio = 0.0000E+00
1 t 0.0000E+00 dt 1.00E-02 flush i/o buffers 01/27/26 14:40:35
1 t 0.0000E+00 dt 1.00E-02 write d3plot file 01/27/26 14:40:35
Implicit dynamics is now active
BEGIN implicit dynamics step 1 t= 1.0000E-02 01/27/26 14:40:35
============================================================
time = 1.00000E-02
current step size = 1.00000E-02
================================================
== IMPLICIT USAGE ALERT ==
================================================
== Memory Management for Implicit has changed ==
== after R10. Please use: ==
== memory= 1M memory2= 1M ==
================================================
===================================================================================
= BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES
= RANK 0 PID 19 RUNNING AT 6c9a4250757f
= KILLED BY SIGNAL: 7 (Bus error)
===================================================================================
===================================================================================
= BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES
= RANK 1 PID 20 RUNNING AT 6c9a4250757f
= KILLED BY SIGNAL: 9 (Killed)
===================================================================================
Total running time of the script: (0 minutes 21.696 seconds)