tosca

name	tosca
description	Tosca .par file authoring for topology, shape, bead, and sizing optimization. Covers block syntax, design responses, constraints, objectives, optimization parameters, and STL export. This is the definitive reference for hand-written .par files.
allowed-tools	["Read","Write","Edit","Glob","Grep","Bash(abaqus:*)","Skill"]

Tosca .par File Authoring

Complete reference for writing Tosca Structure parameter files (.par) that define optimization problems. Every .par file in this project is hand-written -- no API generates valid ones.

When to Use This Skill

Triggers: .par file, parameter file, design response, DRESP, objective function, OBJ_FUNC, optimization constraint, CONSTRAINT, Tosca parameters, OPT_PARAM, SIMP penalty, filter radius, sensitivity strategy, TOPO_SENSITIVITY, DV_TOPO, DVCON_TOPO, FEM_INPUT, SMOOTH block, SIG_SENS_MISES, volume fraction, material interpolation, MIMP, RAMP

USE for:

• Creating new .par files from scratch
• Adding/modifying blocks in existing .par files
• Debugging Tosca optimization failures caused by .par syntax
• Understanding block dependencies and required fields
• Configuring stress constraints, manufacturing constraints, or multi-load-case setups

Do NOT use for:

• Abaqus .inp file creation -> use /abaqus-* skills
• Running Tosca from Python API -> Tosca uses CLI only
• Post-processing ODB results -> use /abaqus-odb
• Abaqus CAE topology optimization setup -> use /abaqus-topology-optimization

Prerequisites

1. A valid Abaqus .inp file (the FEA model to optimize)
2. Element sets and node sets defined in the .inp file (referenced by GROUP_DEF or directly)
3. Full Abaqus license with Tosca module (not Learning Edition)
4. Understanding of the physical optimization goal

What to Ask the User

Critical -- must know before writing any .par file:

1. What is the optimization type? (topology, shape, bead, sizing)
2. What is the objective? (minimize volume, minimize compliance/strain energy, maximize frequency)
3. What constraints apply? (stress limit, displacement limit, volume fraction)
4. What is the volume fraction target/limit? Volume constraints are ALWAYS required — even when minimizing volume. Without a volume upper bound, the optimizer removes all material in one cycle.
5. What element groups define the design space vs. frozen regions?

With sensible defaults:

• Material interpolation: SIMP (default, good for compliance; use MIMP for stress)
• Penalty factor: 3.0 (range 2-4; higher = sharper solid/void boundary)
• Filter radius: 1.3 * avg element edge length (controls min member size)
• Max iterations: 50 for compliance, 80 for stress-constrained
• Move limit (DENSITY_MOVE): 0.25 for compliance, 0.10 for stress
• Strategy: TOPO_SENSITIVITY (always for topology with constraints)
• ISO_VALUE for SMOOTH: 0.3 (range 0.2-0.5)

Block Dependency Order

A valid .par file must define blocks in dependency order:

FEM_INPUT       -> references the .inp file
GROUP_DEF       -> defines element/node groups (optional if sets exist in .inp)
DV_TOPO         -> references EL_GROUP (design space)
DVCON_TOPO      -> references EL_GROUP (frozen regions, manufacturing constraints)
DRESP           -> references EL_GROUP or ND_GROUP (what to measure)
OBJ_FUNC        -> references DRESP (what to optimize)
CONSTRAINT      -> references DRESP (limits on responses)
OPTIMIZE        -> ties DV, OBJ_FUNC, DVCON, CONSTRAINT together
OPT_PARAM       -> references OPTIMIZE (tuning knobs)
STOP            -> iteration limit and convergence criteria
SMOOTH          -> post-processing: isosurface extraction and STL export

Quick Reference

See detailed documentation in references/:

• par-file-syntax.md -- Complete block-by-block syntax reference
• design-responses.md -- All DRESP types with usage rules
• common-patterns.md -- Ready-to-use .par templates for 5 common setups
• troubleshooting.md -- Error diagnosis, convergence fixes, common pitfalls

Validation Checklist

Before running Tosca with a .par file:

Check	How
Every block ends with END_	Search for missing terminators
No line exceeds 160 characters	Tosca silently truncates long lines
EL_GROUP names match .inp set names exactly	Case-sensitive match
DRESP referenced in OBJ_FUNC/CONSTRAINT exists	Cross-reference ID_NAMEs
OPTIMIZE references all DV, OBJ_FUNC, DVCON, CONSTRAINT	Nothing orphaned
OPT_PARAM references the correct OPTIMIZE	Name must match
.inp file path in FEM_INPUT is correct	Relative to Tosca working directory
SIG_SENS_MISES DRESP excludes loaded/BC nodes	Prevents stress singularities
For stress problems: ITER_MAX >= 75, DENSITY_MOVE <= 0.15	Stress needs more iterations

Running Tosca

# From the directory containing both .par and .inp files:
"C:/SIMULIA/Commands/abaqus.bat" tosca --job <par_file_without_extension> 2>&1

# Example:
"C:/SIMULIA/Commands/abaqus.bat" tosca --job Exp10_TO 2>&1

Related Skills

• /abaqus-topology-optimization -- Abaqus CAE side of topology optimization
• /abaqus-optimization -- Abaqus Python API for optimization setup
• /abaqus-geometry -- Creating the design space geometry
• /abaqus-mesh -- Meshing for optimization (fine mesh, C3D8R or C3D10)