composite-curing-simulation

Composite Curing Simulation

This is the master routing skill for composite material curing simulation. It provides an overview and routes to specialized sub-skills for each aspect of the workflow.

When to Invoke

• User requests composite curing simulation with mold
• User mentions "固化仿真", "脱模回弹", "模具", "铺层"
• User wants to change ply angles or ply count in a curing model
• User needs to run Abaqus with UMAT for composite materials
• User provides a reference INP with mold/contact/temperature and wants to replicate it

Critical: Mold Constraint vs No-Mold Constraint

This is the most important distinction in the curing model. Using the wrong constraint type produces physically incorrect results.

P8_mold (Correct — With Mold Contact + Demolding)

The correct model includes a TOOL part, friction contact pairs, and Model Change demolding in the sp step. This produces asymmetric springback deformation reflecting real physics.

Feature	P8_mold (Correct)
TOOL part	Present (TOOL-1 instance)
Contact pair	com-surface (S1) ↔ tool-surface (S4+S6), HARD contact
Friction	Temperature-dependent: 0.45 → 0.2 → 0.169
Curing constraint	Mold contact (TOOL U1=0, U2=0 via _PickedSet327/328)
Demolding	*Model Change, remove on TOOL elements + contact pair in sp step
Springback constraint	Set-2 (inner corner nodes): U1=U2=U3=0 via *Boundary, op=NEW
Pressure	0.6 MPa on S2 (inner surface), removed in sp step
Springback contour	Asymmetric (max displacement at free edges)
Spring-in angle	Positive (0.5°-1.6°), physically correct

P8_only (Incorrect — No Mold, ENCASTRE Constraint)

The incorrect model omits the TOOL part and uses ENCASTRE (full fixity) instead of mold contact. This produces center-symmetric deformation that does NOT reflect real curing physics.

Feature	P8_only (Incorrect)
TOOL part	Absent
Contact pair	None
Friction	None
Curing constraint	ENCASTRE (U1=U2=U3=UR1=UR2=UR3=0) on inner surface
Demolding	None (no mold to remove)
Springback constraint	Same ENCASTRE remains
Springback contour	Center-symmetric (unphysical)
Spring-in angle	Does not reflect real physics

Why P8_only is Wrong

1. No mold contact: Without the TOOL part, there is no frictional constraint during curing. The composite is artificially fixed via ENCASTRE, which prevents any thermal expansion-driven slip at the mold interface.
2. No demolding process: The *Model Change step is what creates the physical springback mechanism — releasing the part from the mold allows residual stresses to relax into the final shape. Without it, the model simply releases a fully constrained part.
3. Center-symmetric artifact: ENCASTRE creates a symmetric constraint pattern, leading to symmetric deformation. Real curing springback is asymmetric because friction varies across the part surface.
4. Missing friction history: The temperature-dependent friction (0.45→0.2→0.169) captures the material state transitions (viscous→rubbery→glassy). Without contact, this physics is entirely absent.

Template File

• Correct template: P8_mold_V2.inp — use this for all new simulations
• Incorrect template: P8_only_recipe_1.inp — do NOT use; archived for reference only

Skill Architecture

composite-curing-simulation/
├── README.md                          # English overview
├── README.zh-CN.md                    # Chinese overview
├── SKILL.md                           # This file (master router)
├── core/
│   └── composite-curing/              # Main routing logic
├── modeling/
│   ├── composite-layup/               # Ply angles, thickness, count
│   ├── mold-geometry/                 # Tool/mold part setup
│   └── composite-mesh/               # C3D8 mesh, through-thickness
├── setup/
│   ├── curing-material/               # UMAT, COM/TOOL materials
│   ├── curing-contact/                # Contact pairs, friction
│   ├── curing-bc/                     # Boundary conditions, Set-2
│   ├── curing-load/                   # Pressure on inner surface
│   └── curing-temperature/            # Temperature fields
├── analysis/
│   ├── curing-steps/                  # 4-step process (vis/rub/glassy/sp)
│   └── springback-analysis/           # Model Change, mold removal
├── execution/
│   ├── curing-job/                    # Job submission with UMAT
│   └── socket-bridge/                 # Socket bridge connection
├── postprocessing/
│   ├── odb-extraction/                # ODB field output reading
│   └── csv-export/                    # CSV with coords + displacement
└── reference/
    └── curing-parameters/             # Complete parameter tables

Quick Reference

4-Step Curing Process

Step	Temperature	Pressure	Friction	Tool BC	Composite BC	Contact
vis	25→150°C	0.6 MPa (S2)	0.45	U1=0, U2=0	—	Active
rub	150→180°C	0.6 MPa (S2)	0.2	U1=0, U2=0	—	Active
glassy	180→25°C	—	0.169	U1=0, U2=0	—	Active
sp	25°C	— (removed)	—	— (removed)	Set-2: U1=U2=U3=0	Removed

Constraint Summary (Critical)

Phase	What is Constrained	How	Purpose
Curing (vis/rub/glassy)	TOOL-1: U1=0, U2=0	_PickedSet328, 1, 1 and _PickedSet327, 2, 2	Fix mold in space; composite held by friction
Curing (vis/rub/glassy)	Composite	Mold contact (friction)	Composite can slide/expand against mold
Springback (sp)	TOOL-1	Removed via *Model Change	Mold is gone
Springback (sp)	Composite: Set-2	*Boundary, op=NEW → U1=U2=U3=0	Prevent rigid body motion only

Routing Guide

User Request	Route To
Change ply angles	modeling/composite-layup
Change ply count	modeling/composite-layup + modeling/composite-mesh
Set up mold	modeling/mold-geometry
Define UMAT material	setup/curing-material
Set up contact/friction	setup/curing-contact
Define boundary conditions	setup/curing-bc
Apply pressure	setup/curing-load
Set temperature fields	setup/curing-temperature
Configure curing steps	analysis/curing-steps
Set up springback	analysis/springback-analysis
Submit job with UMAT	execution/curing-job
Connect to Abaqus	execution/socket-bridge
Extract ODB results	postprocessing/odb-extraction
Export CSV data	postprocessing/csv-export
Batch extract + screenshots	abaqus-odb-extraction (standalone skill)
Look up parameters	reference/curing-parameters

Recommended Workflow Chain

core/composite-curing          → Start here
modeling/composite-layup       → Define plies
modeling/mold-geometry         → Set up mold
modeling/composite-mesh        → Verify mesh
setup/curing-material          → UMAT + TOOL materials
setup/curing-contact           → Contact + friction
setup/curing-bc                → Tool BCs + Set-2
setup/curing-load              → Pressure on S2
setup/curing-temperature       → Temperature fields
analysis/curing-steps          → 4-step sequence
analysis/springback-analysis   → Model Change
execution/curing-job           → Submit with UMAT
execution/socket-bridge        → Connect to Abaqus
postprocessing/odb-extraction  → Read results
postprocessing/csv-export      → Export data
abaqus-odb-extraction          → Batch automate (standalone skill)

Key Files

• Correct template INP: P8_mold_V2.inp — contains TOOL part, contact, Model Change
• Incorrect template INP: P8_only_recipe_1.inp — archived, do NOT use
• UMAT subroutine: Threestep.for (4434 bytes, 4 state variables)
• Environment file: abaqusis.env (domains=4, no_domain_check=ON, ask_delete=OFF)
• Abaqus CAE: Must be open with socket bridge plugin (port 48152)

Dataset Generation

For generating large datasets (50-100 cases) from the P8_mold_V2 template:

1. INP generation: Read template, replace 8 ply lines (indices 14153-14160), format: 0.250, 3, COM, <angle>, Ply-N
2. Batch submission: abq2020.bat job=NAME user=Threestep.for cpus=4 interactive
3. ODB extraction: abq2020.bat python extract_via_cli.py (bypasses CAE filesystem isolation)
4. Spring-in calculation: SVD dual-arm plane fit on deformed coordinates
5. Screenshots: abq2020.bat cae noUI=screenshot.py with LeafFromPartInstance to hide mold

See the standalone abaqus-odb-extraction skill for complete automation scripts.

Common Pitfalls

1. Using P8_only instead of P8_mold: Always use P8_mold_V2.inp as template. P8_only lacks mold contact and produces center-symmetric (unphysical) results.
2. Ply count vs ply angles: Changing ply angles is a text edit (replace ply lines); changing ply count requires mesh regeneration.
3. Pressure surface: Pressure is on S2 (inner surface), NOT S1 (outer/contact surface).
4. Tool node numbering: Tool and composite parts both start from node 1. Parse per-part.
5. Set-2 node matching: When mesh changes, match nodes by coordinates, not node ID.
6. Filesystem isolation: TRAE sandbox files are invisible to Abaqus CAE. Use C:\Temp or abq2020.bat for file operations.
7. Python 2 vs 3: Abaqus uses Python 2.7 — no f-strings, no exist_ok, print is statement in some contexts.
8. MCP submit_job encoding bug: TypeError: unicode argument expected, got 'str' — use command-line abq2020.bat instead.