FESADev/docs/io-definitions/abaqus-input-parser-io.md

Abaqus Input Parser I/O Definition

Metadata

• feature_id: abaqus-input-parser
• status: ready-for-implementation-planning
• owner_agent: io-definition-agent
• date: 2026-06-12

Abaqus Input Scope

FESA supports only the Abaqus input keyword subset listed here. This document does not claim full Abaqus compatibility.

keyword	support_status	level	required_parameters	mapped_internal_concept	unsupported-case behavior
*HEADING	supported	model	none	model title metadata	accepted; title storage may be deferred
*NODE	supported	model	none	node id and global coordinates	malformed rows are errors
*ELEMENT	supported	model	TYPE	element id, topology, connectivity	missing/unsupported TYPE is an error
*NSET	supported	model	NSET	named node set	missing name is an error
*ELSET	supported	model	ELSET	named element set	missing name is an error
*MATERIAL	supported	model	NAME	material identity	missing name is an error
*ELASTIC	supported	model	none	linear elastic constants	malformed rows are errors
section keyword	supported	model	ELSET, MATERIAL	property assignment	unsupported section type is an error
*STEP	supported	history	optional NAME	analysis step	malformed parameters are errors
*STATIC	supported	history	none	static procedure marker	unsupported procedures are errors
*BOUNDARY	supported	model/history	none	prescribed nodal dof values	malformed rows are errors
*CLOAD	supported	history	none	concentrated nodal load	malformed rows are errors
*OUTPUT	supported	history	none	output request root	unsupported options warn or error by context
*NODE OUTPUT	supported	history	none	nodal output request	unsupported quantities warn or error by context
*ELEMENT OUTPUT	supported	history	none	element output request	unsupported quantities warn or error by context

Initial V0 element names are two-node line/bar types only: T2D2, T3D2, C3D2, and B31.

Syntax Policy

• Keywords and parameter names are case-insensitive.
• Keyword lines begin with *.
• Comment lines begin with ** and are ignored.
• Blank lines are ignored.
• Fields are comma-separated. Leading and trailing whitespace around fields is ignored.
• Empty required fields are parse errors.
• Unsupported keywords are errors unless this contract explicitly marks them as ignored-with-warning.
• Diagnostics must include severity, a stable code, a human-readable message, and enough line context to locate the input row.
• Include files are out of scope for this parser phase.

Model Data Mapping

• Nodes map an Abaqus node label to a FESA node id and three global coordinate components. Missing trailing coordinate components are interpreted as 0.0 only when the keyword-specific test documents that behavior.
• Elements map an Abaqus element label, supported element type, and connectivity labels to a FESA element. Section assignment supplies material/property linkage in a later parser slice.
• Node sets and element sets preserve deterministic membership order.
• Materials map by Abaqus NAME. Linear elastic data maps to the semantic material contract used by solver implementation.
• Section keywords bind an element set to a material and create the semantic property assignment needed by the solver.
• The global coordinate system is assumed. Units are user-consistent and are not converted by the parser.

History Data Mapping

• *STEP begins an ordered analysis step. If no name is provided, the parser assigns a deterministic step name or id.
• *STATIC marks the step as a linear static procedure for V0.
• *BOUNDARY maps node id, dof range, and value to prescribed boundary conditions.
• *CLOAD maps node id, dof component, and magnitude to concentrated loads.
• Output request keywords define requested quantities when semantic storage exists; unsupported quantities must not be silently accepted.

Internal Model Contract

• Domain owns model definition data created from the input file.
• Parsed model objects should be treated as immutable after parsing where practical.
• AnalysisStep owns step-local boundary conditions and loads.
• The parser must not store equation ids on nodes or elements.
• Parser diagnostics are part of the result; callers do not need to inspect partial Domain state to detect failure.

Output HDF5 Schema

The parser itself does not write HDF5. Solver output remains authoritative in results.h5 and follows the project HDF5 contract:

quantity	dataset_path	location	component policy
displacement	/steps/<step>/frames/<frame>/field_outputs/U	nodal	U1, U2, U3 as applicable
reaction	/steps/<step>/frames/<frame>/field_outputs/RF	nodal	RF1, RF2, RF3 as applicable
internal force	/steps/<step>/frames/<frame>/field_outputs/element_forces	element	feature-specific
stress	/steps/<step>/frames/<frame>/field_outputs/S	integration point or element	feature-specific

Required metadata includes schema version, model id, source input identity, coordinate system, units policy, solver version, step/frame identity, and row identity fields.

FESA HDF5 To Reference CSV Comparison Schema

Reference comparison reads results.h5 and matches deterministic rows against Abaqus-generated CSV files under reference/<model-id>/. This parser phase does not generate or modify those reference artifacts.

Common row identity:

• sort order: step, frame, entity id, location, component
• node id and element id are Abaqus labels preserved by the parser
• component names follow the HDF5 component policy

CSV files remain:

• <model-id>_displacements.csv
• <model-id>_reactions.csv
• <model-id>_internalforces.csv
• <model-id>_stresses.csv

Validation Rules

• Duplicate node, element, material, property, set, or step labels are errors.
• Missing references are errors.
• Unsupported keywords are errors unless explicitly documented otherwise.
• Malformed numeric fields are errors.
• Parser unit tests must cover valid subset mapping and invalid subset diagnostics before production parser changes.
• Workspace validation remains python scripts/validate_workspace.py.

Downstream Handoff

Implementation planning should split work into mesh keyword parsing, diagnostics, set/section mapping, material/history mapping, and integration validation. Reference model work may later use this subset to prepare reference/<model-id>/model.inp, but this phase must not create or modify Abaqus reference CSV artifacts.