abaqus-mesh

# Abaqus Mesh Skill Generate finite element meshes for Abaqus models. Discretizes geometry into elements and nodes for analysis. ## When to Use This Skill **Route here when user mentions:** - "Mesh the part", "generate mesh" - "Element size", "mesh size", "refine mesh" - "Element type", "C3D8R", "C3D10", "S4R" - "Too many nodes", "Learning Edition limit" - "Mesh quality", "check elements" **Route elsewhere:** - Creating or modifying geometry → `/abaqus-geometry` - Creating partitions for loads/BCs → `/abaqus-geometry` - Extracting mesh-based results → `/abaqus-odb` ## Prerequisites Before meshing: 1. Geometry must be complete 2. Sections should be assigned (material assignment) ## Workflow: Generating a Mesh ### Step 1: Understand User's Goal Ask if unclear: - **Target mesh size?** Coarse (fast) or fine (accurate)? - **Hex or tet elements?** Simple geometry → hex; complex → tet - **Local refinement?** Stress concentrations need finer mesh ### Step 2: Choose Element Type | Geometry | Recommended | Code | Notes | |----------|-------------|------|-------| | Simple box/prism | Hex, reduced | C3D8R | Fast, accurate, try first | | Complex freeform | Tet, quadratic | C3D10 | Meshes anything | | Thin-walled (t/L < 0.1) | Shell | S4R | Plates, shells | | Slender beams (L/d > 10) | Beam | B31 | Frames, trusses | **Decision guidance:** - Can it be hex-meshed? → Try C3D8R first - Complex shape or holes? → Use C3D10 (tet) - Thin structure? → Use S4R shell - Explicit dynamics? → C3D8R works well ### Step 3: Choose Mesh Size | Use Case | Element Size | Guideline | |----------|--------------|-----------| | Quick feasibility | 10-20mm | 5+ elements across model | | General analysis | 3-5mm | 10+ elements across smallest dimension | | Stress concentrations | 1-2mm | 5+ elements in high-gradient regions | | Topology optimization | 2-5mm | 3-5 elements across expected members | **Rule of thumb:** At least 3 elements across any feature you care about. ### Step 4: Check Learning Edition Limits Learning Edition allows max 1000 nodes. | Box Dimensions (mm) | Max Element Size | |--------------------|------------------| | 100 x 100 x 100 | 20mm | | 100 x 50 x 30 | 10mm | | 50 x 50 x 50 | 12mm | | 200 x 100 x 50 | 25mm | **Estimation formula:** `nodes ≈ (L/size + 1) × (W/size + 1) × (H/size + 1)` ### Step 5: Apply Local Refinement (If Needed) Refine mesh near: - Holes and notches (stress concentrations) - Fillets and sharp corners - Load/BC application points Options: - Edge seeds with smaller size - Edge seeds with specific element count - Biased mesh (graded density) ### Step 6: Generate and Verify After mesh generation, check: - [ ] Node count within limits - [ ] Element count reasonable - [ ] No mesh quality warnings - [ ] Elements exist in all regions ## Element Type Reference ### 3D Solid Elements | Code | Type | Nodes | Use Case | |------|------|-------|----------| | C3D8R | Hex, reduced | 8 | General purpose (recommended) | | C3D8 | Hex, full | 8 | Bending-dominated, no hourglass | | C3D20R | Hex, quadratic | 20 | High accuracy, expensive | | C3D4 | Tet, linear | 4 | Complex geometry (less accurate) | | C3D10 | Tet, quadratic | 10 | Complex geometry (better accuracy) | ### Shell Elements | Code | Type | Nodes | Use Case | |------|------|-------|----------| | S4R | Quad, reduced | 4 | General purpose (recommended) | | S4 | Quad, full | 4 | No hourglass | | S3 | Triangle | 3 | Complex surfaces | ## Mesh Quality Guidelines | Metric | Target | Warning | Failure | |--------|--------|---------|---------| | Aspect ratio | < 5:1 | 5-10:1 | > 10:1 | | Jacobian | > 0.5 | 0.1-0.5 | < 0.1 | | Min angle (quad) | > 45° | 30-45° | < 30° | ## Troubleshooting | Problem | Likely Cause | Solution | |---------|--------------|----------| | "Cannot mesh region" | Geometry too complex for hex | Switch to TET with FREE technique | | "Element distortion" | Poor element shapes | Refine locally or fix geometry | | "Exceeded node limit" | Mesh too fine | Increase element size | | "No mesh controls" | Missing mesh technique | Set mesh controls before generating | | Mesh won't generate | Gaps in geometry | Check geometry, merge if needed | ## Code Patterns For API syntax and code examples, see: - [API Quick Reference](references/api-quick-ref.md) - [Common Patterns](references/common-patterns.md) - [Element Library](references/element-library.md)