Pfc Contact Models

PFC Contact Models

Use this skill to choose, explain, adapt, or audit PFC contact-model setups. The skill is self-contained: PFC 6.0 linear and linear-parallel-bond examples are stored under scripts/canonical/, and documentation notes checked through pfc-mcp are stored under references/contact-model-doc-notes.md.

Parent Skill Relationship

pfc-contact-models is a child skill of pfc-workflow. It does not own the full PFC lifecycle. Use it for contact-law selection, CMAT/property setup, bond activation, stiffness/strength property audits, and contact-model migration notes. Return to pfc-workflow for full case planning, solve orchestration, post-processing routing, verification, and delivery.

Parent/child split:

• Parent pfc-workflow: owns complete PFC project lifecycle and decides when contact-model support is needed.
• Child pfc-contact-models: owns contact laws, CMAT, contact properties, contact methods, bond setup, and contact-law validation checks.
• Sibling child pfc-fish: owns detailed FISH helper/callback implementation.
• Sibling child pfc-servo-calibration: owns servo control and manual macro-calibration sequencing.
• Sibling child pfc-standard-tests: owns standard laboratory-test templates.
• Sibling child pfc-dynamics: owns dynamic/seismic loading assumptions.
• Sibling child pfc-fluid-coupling: owns PFC CFD/seepage/buoyancy workflows.
• Sibling child pfc-flac-coupling: owns PFC-FLAC/FLAC3D coupling.
• Sibling child pfc-postprocessing: owns standard figures and field exports after solve.
• Sibling child pfc-ae-energy: owns AE, energy, and source-mechanism outputs after solve.

When To Use

Use through pfc-workflow when a task needs contact-law reasoning:

• choose between linear, linearpbond, linearcbond, hertz, flatjoint, smoothjoint, softbond, rrlinear, or plugin contact laws
• set CMAT defaults before contact creation
• assign or modify properties on existing contacts
• activate bonds or set deformability through contact methods
• explain property inheritance from ball/wall/clump surfaces
• audit legacy contact-property blocks for PFC 6.0 compatibility
• connect micro-properties to macro-test calibration requirements

Required Inputs

Ask for these if missing:

• PFC version and dimensionality.
• Material behavior: unbonded granular, cemented/rock-like, nonlinear elastic, jointed, rolling-resistance, or plugin-defined.
• Contact types involved: ball-ball, ball-facet, pebble-pebble, rblock, fracture, or mixed.
• Target macro behavior: stiffness, friction angle, tensile strength, cohesion, peak/residual behavior, dilation, or damage pattern.
• Whether contacts already exist or CMAT will be set before model clean.
• Calibration/validation test: UCS, Brazilian, biaxial, triaxial, direct shear, contact-level two-ball test, or custom.

Documentation-Backed Rules

The following PFC 6.0 documentation points were checked through pfc-mcp and are expanded in references/contact-model-doc-notes.md:

• contact cmat default defines default Contact Model Assignment Table behavior for future contacts.
• contact model changes existing contacts and replaces prior contact-model state.
• contact property changes properties on existing contacts that recognize the property.
• contact method executes model-specific operations such as bond, deformability, or pb_deformability.
• contact cmat apply applies CMAT to existing contacts and reassigns contact models.
• contact list is used to verify contact model, force, energy, and contact state.
• ball property and wall property assign surface properties used by contact models; they are distinct from attributes.
• model clean creates contacts and initializes contact state after pieces/geometry are created.

Canonical Template Map

Contact-Model Checklist

Use this checklist before writing or changing contact logic:

1. Select the contact law according to material behavior, not just available properties.
2. Define CMAT rules before creating/cleaning contacts whenever possible.
3. Run model clean after piece creation and before assuming contacts exist.
4. Use contact method bond only after compatible contacts exist.
5. Use contact property only when intentionally changing existing contacts.
6. Document whether properties are contact-level, ball/wall surface-level, inherited, or method-derived.
7. Add histories or contact listings that verify force, displacement, bond stress, failure, or energy response.
8. Route macro calibration back through pfc-workflow and, when needed, pfc-servo-calibration or pfc-standard-tests.

Working Rules

• Prefer PFC 6.0-safe syntax unless the user explicitly targets another version.
• Treat files in scripts/canonical/ as reference templates, not final calibrated models.
• Do not publish generated .sav, project metadata, videos, PDFs, archives, or large output dumps as authoritative assets.
• Do not claim macro mechanical behavior from micro-properties without calibration or validation.
• If the task becomes a full calibration or validation study, hand control back to pfc-workflow.

Output Contract

A complete child-skill handoff back to pfc-workflow should include:

• Selected contact law and why it fits.
• Required files or snippets from scripts/canonical/<case>/.
• CMAT/property/method command order.
• Existing-contact vs future-contact assumptions.
• Required histories/list checks for validation.
• Macro-calibration caveats and target tests.
• A clear note that full case execution, post-processing routing, V&V, and delivery continue in pfc-workflow.

Local Contents

• references/overview.md: detailed self-contained contact-model boundaries and source map.
• references/contact-model-doc-notes.md: PFC 6.0 command/reference notes checked through pfc-mcp.
• examples/README.md: how to validate bundled contact-model demonstrations.
• scripts/canonical/: PFC contact-model source snippets.
• scripts/canonical/manifest.json: file inventory with sizes and SHA-256 hashes.
• scripts/README.md: helper-script policy and future maintenance guidance.