Cross-vendor terminology Rosetta

Every commercial FEA package developed its own dialect. The same idea has different names — and worse, sometimes the same name means different things across vendors. This Rosetta table maps femorph-solver’s vocabulary against the four most-encountered commercial codes (ANSYS Mechanical APDL, MSC / NX Nastran, Abaqus / SIMULIA, LS-DYNA) plus the Code_Aster open-source family where its conventions add useful context.

Use it two ways:

• You learned FEA on MAPDL — read the MAPDL column to find the femorph-solver vocabulary you’ll see in this docs corpus.

• You’re authoring an interop layer — read the femorph-solver column to find the cards / keywords / commands the foreign reader has to map onto.

The table is curated for the linear-elastic structural-mechanics slice femorph-solver ships today. Non-linear, contact, plasticity, and explicit-dynamics rows are added as those analysis types land.

Element types

femorph-solver	ANSYS Mechanical APDL	Cross-vendor equivalents
ELEMENTS.HEX8	SOLID185	NASTRAN CHEXA(8); Abaqus C3D8 / C3D8I; LS-DYNA ELFORM=1/2
ELEMENTS.HEX20	SOLID186	NASTRAN CHEXA(20); Abaqus C3D20 / C3D20R; LS-DYNA ELFORM=23
ELEMENTS.TET10	SOLID187	NASTRAN CTETRA(10); Abaqus C3D10; LS-DYNA ELFORM=16
ELEMENTS.QUAD4_PLANE	PLANE182	NASTRAN CQUAD4 (PSHELL plane-stress); Abaqus CPS4 / CPE4 / CAX4
ELEMENTS.QUAD4_SHELL	SHELL181	NASTRAN CQUAD4 (PSHELL); Abaqus S4 / S4R; LS-DYNA ELFORM=2/16
ELEMENTS.BEAM2	BEAM188	NASTRAN CBEAM / CBAR; Abaqus B31 / B33; LS-DYNA ELEMENT_BEAM
ELEMENTS.TRUSS2	LINK180	NASTRAN CROD / CTUBE; Abaqus T3D2; LS-DYNA ELFORM=3
ELEMENTS.SPRING	COMBIN14	NASTRAN CELAS1 / CELAS2; Abaqus SPRING1 / SPRING2; LS-DYNA ELEMENT_DISCRETE
ELEMENTS.POINT_MASS	MASS21	NASTRAN CONM1 / CONM2; Abaqus MASS; LS-DYNA ELEMENT_MASS
ELEMENTS.WEDGE15	SOLID186 (degenerate)	NASTRAN CPENTA(15); Abaqus C3D15
ELEMENTS.PYR13	SOLID186 (apex-singular)	NASTRAN CPYRAM(13); Abaqus C3D13

Each ELEMENTS.* entry has its own technical sheet under Element kernels.

Boundary conditions

femorph-solver	ANSYS Mechanical APDL	Cross-vendor equivalents
Model.fix(node, dof)	D, node, dof, value	NASTRAN SPC1; Abaqus *BOUNDARY; LS-DYNA *BOUNDARY_SPC_NODE
fixed value (Dirichlet)	D, node, label, val	NASTRAN SPC enforced-displacement; Abaqus *BOUNDARY with two values
Model.fix(dof="ALL")	D, all, ALL	NASTRAN SPC1, SID, 123456; Abaqus *BOUNDARY, ENCASTRE; LS-DYNA flags 111111
symmetry plane	D, sym_face, U?	NASTRAN SPC1 on the through-plane DOF; Abaqus *BOUNDARY, XSYMM
cyclic / sector	CP / CPCYC	NASTRAN MPC cyclic; Abaqus *MPC, CYCLSYM; (LS-DYNA: contact only)

Loads

femorph-solver	ANSYS Mechanical APDL	Cross-vendor equivalents
Model.apply_force(fy=)	F, node, FY, value	NASTRAN FORCE card; Abaqus *CLOAD; LS-DYNA *LOAD_NODE_POINT
Model.apply_force(mz=)	F, node, MZ, value	NASTRAN MOMENT card; Abaqus *CLOAD on rotation DOFs
distributed pressure	SF, face, PRES, value	NASTRAN PLOAD2 / PLOAD4; Abaqus *DLOAD, P; LS-DYNA *LOAD_SEGMENT
gravity / body force	ACEL, gx, gy, gz	NASTRAN GRAV card; Abaqus *DLOAD, GRAV; LS-DYNA *LOAD_BODY_X/Y/Z
thermal load	BFE, elem, TEMP, val	NASTRAN TEMP card; Abaqus *TEMPERATURE; LS-DYNA *LOAD_THERMAL_VARIABLE

Material properties

femorph-solver	ANSYS Mechanical APDL	Cross-vendor equivalents
"EX" (Young’s modulus)	MP, EX, mat, value	NASTRAN MAT1 (E field); Abaqus *ELASTIC, type=ISO; LS-DYNA *MAT_ELASTIC
"PRXY" (Poisson ratio)	MP, PRXY, mat, value	NASTRAN MAT1 (NU field); Abaqus *ELASTIC (NU); LS-DYNA (PR field)
"DENS" (density)	MP, DENS, mat, value	NASTRAN MAT1 (RHO field); Abaqus *DENSITY; LS-DYNA (RO field)
orthotropic	MP, EX/EY/EZ + GXY	NASTRAN MAT9; Abaqus *ELASTIC, type=ENGINEERING_CONSTANTS

Analysis types

femorph-solver	ANSYS Mechanical APDL	Cross-vendor equivalents
Model.solve_static()	ANTYPE, STATIC + SOLVE	NASTRAN SOL 101; Abaqus *STATIC; LS-DYNA implicit *CONTROL_IMPLICIT_GENERAL
Model.solve_modal()	ANTYPE, MODAL + MODOPT	NASTRAN SOL 103; Abaqus *FREQUENCY; LS-DYNA *CONTROL_IMPLICIT_EIGENVALUE
Model.solve_transient()	ANTYPE, TRANS	NASTRAN SOL 109 / SOL 112; Abaqus *DYNAMIC; LS-DYNA explicit native
Model.solve_harmonic()	ANTYPE, HARMIC	NASTRAN SOL 108 / SOL 111; Abaqus *STEADY STATE DYNAMICS
linear buckling (planned)	ANTYPE, BUCKLE	NASTRAN SOL 105; Abaqus *BUCKLE; LS-DYNA *CONTROL_IMPLICIT_BUCKLE

Result quantities

femorph-solver	ANSYS Mechanical APDL	Cross-vendor equivalents
StaticResult.displacement	U array in .RST	NASTRAN OUG block; Abaqus U field; LS-DYNA d3plot “Coordinates”
StaticResult.reaction	RF reactions	NASTRAN OQG block; Abaqus RF field; LS-DYNA constraint-force output
nodal stress	ENS averaged	NASTRAN OES (extrapolated); Abaqus S averaged; LS-DYNA Stress in d3plot
ModalResult.frequency	FREQ output by MODOPT	NASTRAN OEF (frequencies); Abaqus F field; LS-DYNA Frequencies
ModalResult.mode_shapes	EVECTORS in .RST	NASTRAN UVE per-mode; Abaqus UR per-mode; LS-DYNA EigenmodeData

Output formats

femorph-solver	ANSYS Mechanical APDL	Cross-vendor equivalents
.pv (canonical)	—	(no commercial precedent — pyvista-native)
StaticResult.save(...)	.rst written by SOLVE	NASTRAN .op2 / .f06 / .h5; Abaqus .odb / .fil; LS-DYNA d3plot
VTK / ParaView	EXPORT, VTK	NASTRAN no native VTK; Abaqus *OUTPUT, VTK (recent); LS-DYNA via LS-PrePost
mesh-archive ASCII	CDWRITE	NASTRAN BDF write; Abaqus .inp write; LS-DYNA .k keyword file

Solvers

femorph-solver	ANSYS Mechanical APDL	Cross-vendor equivalents
linear direct (Pardiso)	EQSLV, PARDISO	NASTRAN AUTOSPC; Abaqus DIRECT; LS-DYNA LSOLVR=2
linear direct (CHOLMOD)	EQSLV, SPARSE	NASTRAN sparse; Abaqus implicit
linear direct (MUMPS)	external	Code_Aster default; available via Abaqus 2024+
eigensolver shift-invert	MODOPT, LANB	NASTRAN METHOD = LANCZOS; Abaqus EIGSOLVER = LANCZOS
eigensolver LOBPCG	MODOPT, SUBSP	(Code_Aster); not standard in commercial codes

Coordinate systems and units

femorph-solver	ANSYS Mechanical APDL	Cross-vendor equivalents
SI default (m, kg, s, N, Pa)	CSYS, 0 global Cartesian	NASTRAN unit-agnostic (deck-set); Abaqus / LS-DYNA unit-agnostic
right-hand rule	same	same
node-numbering 1-indexed	1-indexed	1-indexed (4-byte signed in LS-DYNA)
DOF order UX UY UZ ROTX..	matches MAPDL	matches NASTRAN; Abaqus uses RX RY RZ — same content, no rename

What’s not on this table

The following analysis types are not yet supported in femorph-solver and therefore have no Rosetta entry — they’ll be added as the corresponding feature lands:

• contact (rigid / penalty / Lagrange-augmented)

• metal plasticity (von-Mises, J2, Drucker-Prager)

• hyperelasticity (Mooney-Rivlin, Ogden, …)

• large-deformation geometric nonlinearity

• coupled thermal-stress

• random-vibration / DDAM (planned, see roadmap)

• explicit dynamics

When any of those types ships, this Rosetta updates with the matching keyword / card / command set across vendors.

Where the Rosetta breaks down

A surprising fraction of FEA mythology is “the X solver does Y slightly differently” — different default integration rules, different mass-lumping conventions, different stress-recovery schemes. This Rosetta table covers the interface vocabulary where the answers genuinely match. The numerical details live in the per-element technical sheets (Element kernels) and the verification gallery (Verification gallery) — both of which carry explicit cross-solver accuracy comparisons against MAPDL VM, NAFEMS, Abaqus AVM, and CalculiX results where available.