LS-DYNA binary output (binout)

The binary file LS-DYNA writes in place of its ASCII databases when *DATABASE_<name> asks for BINARY = 2 or 3: nodout (node histories), glstat (global energies), matsum (per-part energies), elout (element histories), rcforc, secforc, rbdout and the others, all in one file (binout, continued in binout%001...; an MPP run writes one per processor, binout0000...). It is an LSDA file (Livermore Software Data Archival), the container lasso-python and LS-PrePost read. New in v16.12.0.

Format name	lsdyna_binout
Extensions	none: found by its file name, binout or binout0000... (any case), or by its LSDA header
Read / Write	✓ / — (read-only)
Extra dependencies	none

Reading

import meshioplusplus

mesh = meshioplusplus.read("run/binout")                 # the first output
last = meshioplusplus.read("run/binout", time_step=-1)   # the last one

last.points                                  # the nodout nodes where they are now
last.point_data["lsdyna:nid"]                # their ids
last.point_data["displacement"]              # (n, 3); also rotation, velocity, ...
last.field_data["binout:glstat:kinetic_energy"]
last.field_data["binout:matsum:internal_energy"]   # one value per matsum id
last.field_data["binout:matsum:ids"]

meshioplusplus.lsdyna_binout.time_values("run/binout")

meshioplusplus convert run/binout 'nodes_{step}.vtu'   # one point cloud per output
meshioplusplus info run/binout

Both engines read the whole format: the C++ core, and a Python reference reader the core falls back to.

The file

An LSDA file starts with an 8-byte header: its size, the sizes of its length, offset, command and type fields, and its byte order. Records are a length and a command; a chain of symbol tables (reached through offset records) holds directory (CD) and variable (VARIABLE: type, offset, count) entries, and each variable's values sit in a DATA record. The continuation files binout%001... beside the file are read with it. Variable types are 1-, 2-, 4- and 8-byte integers (signed and unsigned), 4- and 8-byte reals, and links to other variables; 1-byte variables are text (titles, dates) and are not read.

Each database is a directory holding metadata (ids, title, legend...) and one folder per output time, d000001, d000002..., each with its time and the variables of that output. elout and jntforc nest one level deeper (elout/beam, elout/shell...).

Steps and data

The steps are nodout's outputs or, in a file without nodout, those of the first database with any (in path order). time_step picks one; read_metadata(...).time_values lists the times; read_sequence walks them.

• Points. With nodout: its nodes (metadata/ids, as point_data["lsdyna:nid"]) at their current coordinates (x_coordinate, y_coordinate, z_coordinate), one vertex cell each. Without it, no points.
• Point data. displacement, rotation, velocity, rotational_velocity, acceleration, rotational_acceleration from nodout's x_/y_/z_ and rx_/ry_/rz_ variables; any other per-node nodout variable under its own name.
• Field data. meshio:time; every other nodout variable as binout:nodout:<variable>; and every other database's latest output at or before the step's time (their times compared in single precision, as the file stores them) as binout:<database>:<variable> (binout:glstat:kinetic_energy, binout:elout/beam:axial), with that output's own time as binout:<database>:time and the database's metadata ids as binout:<database>:ids. The databases write at their own intervals (glstat every second, nodout every tenth of one), so a step can carry an older glstat. Integers stay integers.

Not read

• The databases' text metadata (titles, legends, dates, revisions).
• An MPP run's per-processor files together: each binout0000... reads on its own.

Verification

The layout follows lasso-python's lsda_py3 (BSD 3-Clause), itself LSTC's. The test suite reads a binout LS-DYNA wrote (glstat and rwforc, from Ansys' example data, MIT) and a subset of another (a Hybrid III dummy's nodout, elout/beam, glstat and matsum, rewritten with lasso-python's LSDA writer from the 15 MB original), and every value equals lasso-python's Binout reading; the two engines agree exactly. The full 15 MB original (1001 nodout outputs, 13 databases) and qd-cae's swforc binout were checked outside the suite.