LS-DYNA migration#

LS-DYNA is the dominant explicit-dynamics code for crash and high-rate impact analysis. femorph-solver currently ships implicit linear-elastic analyses only, so the LS-DYNA → femorph-solver migration story is narrower than the MAPDL, NASTRAN, and Abaqus equivalents — most LS-DYNA decks rely on analysis types femorph-solver hasn’t reached yet.

If you have an LS-DYNA deck and want to use femorph-solver today, this page is the realistic assessment of the gap and the workaround paths.

The honest gap analysis#

LS-DYNA decks typically contain at least one of:

  • Explicit time-integration (*CONTROL_TIMESTEP, Belytschko-Tsay shells, single-point hourglass control).

  • Contact (*CONTACT_AUTOMATIC_*, penalty-method formulations).

  • Material plasticity (*MAT_PIECEWISE_LINEAR_PLASTICITY, Johnson-Cook, Cowper-Symonds).

  • Hyperelasticity / foam (*MAT_BLATZ-KO, *MAT_OGDEN).

  • Failure / damage (*MAT_ADD_EROSION).

None of these are shipped in femorph-solver today. The explicit-dynamics analysis type is on the long-range roadmap; contact and plasticity are higher-priority follow-ups but aren’t in any released milestone.

What can be salvaged#

If your LS-DYNA deck is doing implicit linear analysis on linear-elastic material — a small subset of LS-DYNA’s typical use case but not unheard of — the geometry is portable. Workflow:

  1. Convert the LS-DYNA .k keyword file to a NASTRAN BDF deck through LS-PrePost or the open-source ls2bdf converter. LS-DYNA → BDF is the standard intermediate step every commercial migration tool uses.

  2. Read the BDF through femorph_solver.interop.nastran.from_bdf(). See NASTRAN migration for the full BDF coverage.

  3. Apply the implicit-linear solve through Model.solve_static() or Model.solve_modal() as usual.

If your LS-DYNA deck is explicit-dynamics or non-linear, you have a roadmap-block — neither analysis type ships in femorph-solver today. The realistic options:

  • Wait for the analysis type to ship. The roadmap is visible in the GitHub project board; explicit dynamics is currently a future milestone.

  • Run the deck through LS-DYNA itself, export the result fields to d3plot, and convert to .pv for post-processing in the femorph-solver gallery recipes — not currently supported but a future d3plot reader is on the planned-roadmap.

  • Use femorph-solver for an implicit-linear sanity-check pass (modal analysis to identify natural frequencies, a static load case to size the elastic envelope) before running the explicit deck — common practice in rotating-equipment and aerospace workflows.

LS-DYNA → femorph-solver vocabulary#

For the implicit-linear subset, the cross-vendor terminology table at Cross-vendor terminology Rosetta covers every concept. Every ELEMENTS.* entry’s technical sheet (Element kernels) carries an LS-DYNA ELEMENT_* row in its cross-vendor mapping table.

Cross-references#